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93 Blazer 4.3 Vortec CPI won't start.

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Old 03-08-2010, 10:56 PM   #1
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93 Blazer 4.3 Vortec CPI won't start.

I just got this Blazer in nonrunning condition.
The old guy I got it from swears it did run when he parked it but now it won't start.
He had some drunks put a new starter in, I suspect now because they burned the old one out trying to start it, then burned the new one out.
So, I replaced the starter,new cap,rotor,wires,plugs.
removed the plenum and turned the key to pressure up and look for leaks, none.
Have got spray from the poppits, and pressure when the key goes to 60 and when the pump stops drops to about 52-54, holds for 30 min.s at which point it is 30.
When I try to start it will ocasionally fire but not start.
Yes I do have good steady spark at plugs.
Compression 135 average.
I suspected timing error and when checking I found all plug wires off by one terminal, and further check showed distributor to appparently be one tooth off. However the the distributor ddid not appear to have been recently tampered with.
Looking at the crank pulley I see two notches and with the #1 at TDC the notch at the left falls about at the notched marker on the engine.
So I have moved the distributor to match the configuration and the rotor now lines up with #1 on the cap, moved the wires and it now does not act like it is fighting timing but still only fire occasionally with no start.
I read conflicting info on fuel pumpaction and what I get is if I turn the key on the pump runs to 60, shuts down and if I bleed the pressure off it does not restart, is this normal or should it restart when the pressure drops.
Also it will not restart the pump each time the key is cycled whether there is pressure or not.
When I jump the the fuel pump relay so to get max pressure I get 60 psi tops.
The haynes book says to test the pump run a jumper from G on the test block to the pos on the batttery but that does not work.
Haynes sucks, they say to test the relay the car must be running, but anyway I can switch relays.
Any insight here, I'm getting tee d off with this thing and from what I read these 4.3 fuel systems are junk it seems, must be a way to get it fired up.
Is this pressure too low or borderline?

Last edited by tspivak; 03-08-2010 at 10:58 PM.
Old 03-08-2010, 11:52 PM   #2
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Will it fire up with a shot of carb cleaner down the intake? If so, then it is fuel related (will die pretty quickly), if it doesnt fire up suspect ignition. If fuel, check the CTS as pressure sounds adequate maybe the ECM is jacking up the mix.
Old 03-09-2010, 03:45 AM   #3
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Re: 93 Blazer 4.3 Vortec CPI won't start.

so the PCM isn't priming the fuel pump everytime? KG it should stop priming after a couple key-ups. You can ohm the field coil side of the relay, or jump the contact side. If the pressure holds for 30 mins, its pretty obvious you're leakless, so a bad FPR or a bad fuel pump check valve is ruled out. Try firing it on carb spray.

Actually, are you sure the gas in the tank is actually gas/good gas? What's fuel volume look like? There's still gas in the tank, yeah?
Old 03-09-2010, 05:40 PM   #4
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Re: 93 Blazer 4.3 Vortec CPI won't start.

No it would not start with ether, yes it has gas but is low, didn't fill it up because the tank has a leak and I'm changing it and filter, but your speculation about ignition got me thinking again, so i seem to notice that when I go out in the morning or after it has set a good while and try it, it almost fires up.
So when I got home from work today I first checked the fuses as sugjested (no problem) then cranked it up with a new plug out of the hole on the block where I could see it.
The spark was great at first but then died off and started to miss.
Pulled the coil off and checked it best I could against the crappy Haynes test protocal, and it seemed it may be bad.
Shot off the the parts store where the guys are now starting to wonder about me and got a new coil, dropped it in, hit the key and with a lot of smoke and rumble it fires up, after a minute or two all the crap burns out and it runs on its own, not great but running.
I had to shut it down because apparently in trying to get the rusted off stub of the middle plug pass. side out I cracked the dip stick tube and it was putting oil all over the floor.
Oil that seems to have a lot of gas in it by the way.
Threw some absorbent on it and tried to start, no go,bad spark again.
Seems something is losing its ability to make a happy spark after it has had current to it for more than a couple minutes.
On a side note, yes I would say the gas is stale, but I am changing the tank and fuel pump anyway bcause if I have to take the tank off then why not put a pump in.
Interestingly my local parts gut charged me $117.00 Canadian for a complete pump kit.
My local GM dealers list price is $860.00 for the pump only, no thats not a complete fuel system because I did ask that question, just the pump.
Same AC Delco part and part number, in fact they did not have it in stock and were going to bring it over from my parts guy.
No wonder GMs so F-ed up now.
Anyway, with that rant behind me, I would appreciate any thoughts on the ignition issue.
Thanks for your help to this point.
Quote: Originally Posted by lesterl
Will it fire up with a shot of carb cleaner down the intake? If so, then it is fuel related (will die pretty quickly), if it doesnt fire up suspect ignition. If fuel, check the CTS as pressure sounds adequate maybe the ECM is jacking up the mix.

Last edited by tspivak; 03-09-2010 at 05:46 PM.
Old 03-09-2010, 05:48 PM   #5
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Have The Ignition Module Checked...
Old 03-09-2010, 06:01 PM   #6
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Re: 93 Blazer 4.3 Vortec CPI won't start.

I had the same problem with my 94 jimmy. I had to replace the distribitor. It turned out that the reluctor was cracked. I got a rebuilt distributor and it fired right up. It turns out that GM had a problem with the distributor. When I got the rebuilt distributor the internals were upgraded. Hope this helps.
Old 03-09-2010, 06:54 PM   #7
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by mott
I had the same problem with my 94 jimmy. I had to replace the distribitor. It turned out that the reluctor was cracked. I got a rebuilt distributor and it fired right up. It turns out that GM had a problem with the distributor. When I got the rebuilt distributor the internals were upgraded. Hope this helps.
What the heck is a reluctor?
I was thinking pick up coil, would this be intermitent?
Old 03-09-2010, 07:00 PM   #8
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Re: 93 Blazer 4.3 Vortec CPI won't start.

The reluctor is inside the distributor. It looks like a gear. Its job is to signal the ignition to fire the plugs.
Old 03-11-2010, 06:33 PM   #9
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by mott
The reluctor is inside the distributor. It looks like a gear. Its job is to signal the ignition to fire the plugs.
Changed the whole distributor and still bad or no spark.
Old 03-11-2010, 09:11 PM   #10
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Do you have good 12v at the pink wire on the coil? Will grounding the white wire (ignition on) cause a spark out of the coil?
Old 03-14-2010, 10:43 PM   #11
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Okay, this thing still won't run.
I've had the plenum off can can see no leaks under pressure .
I replace coil,ignition module,rotor,cap,wires plugs,taken off egr to verifiy it's clean and working,cleaned sensors,checked conections,changed fuel tank(it was leaking0, changed pump and pulsator(big name for a piece of hose), sock on pickup,disconected and blew out lines and checked for leaks,new filter,oil change,oil filter,new GOOD battery,fresh fuel.
Althought it did relucktently fire up and run yesterday, it will not restart today.
Compression varies from 140 to 150.
Distributor is correctly timed.
Fuel pressure is no different no than before I changed pump and does not leak down at what I would think to be an unreasonable rate.
Priming with ether makes little or no difference.
The new plugs are now covered with black residue and I will change out again this week when time allows.
What the heckis going on with this money pit?
Old 03-15-2010, 05:08 PM   #12
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Bought some NGK platinum point plugs and put them in, findled with the timing and managed to get it running.
I can adjust the timing to get a good idle and no ability to accelerate or accelerate very well with no idle capability.
Will start when I have it set to accelerate and have the throttle to the floor, but won't start at all when it is set to idle well.
What should I be looking at?
Checked for vacumn leaks and fing no evidence of that.
EGR is clean and operating, idle control valve clean and operating.
Fuel pressure at 55-56 when running and holds.
Old 03-15-2010, 06:10 PM   #13
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Re: 93 Blazer 4.3 Vortec CPI won't start.

What does the exhaust smell like? Sounds like it running really really rich. Did you hook it up to check for codes/bad sensors? Sounds like you could have some leaky injectors. Did you pull plugs to see if they are firing?

Last edited by Ajvdub; 03-15-2010 at 06:11 PM.
Old 03-15-2010, 07:25 PM   #14
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Exhaust stinks, old style data link so just codes from engine with no stotred errors.
Engine light flashes saying service engine soon.
All plugs are new premium as stated in previous post.
What I notice is that the spark is good initially but seems to fade after afew cranks.

Last edited by tspivak; 03-15-2010 at 07:27 PM.
Old 03-15-2010, 07:48 PM   #15
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Have you checked to make shure the Balancer hasnt gone bad/ slipped? Cam timing ok?
Old 03-15-2010, 10:02 PM   #16
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by lesterl
Have you checked to make shure the Balancer hasnt gone bad/ slipped? Cam timing ok?
Can you point in the right direction for checking these two items?
Old 03-16-2010, 03:43 PM   #17
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Re: 93 Blazer 4.3 Vortec CPI now starts, continued.

Okay, I don't believe it could be the balancer or a cam problem because when I get it to TDC, line up pulley mark, and set the distributor it stays put.
When it does get running it revs well with the dist. set to do so, but when set to a good idle it won't rev.
When starting the dist. has to be in the position that it was in when it revved well and the throttle to the floor.
Exhaust stinks and I think it is running rich.
I replaced the temp. gauge sensor because when it was running I had no reading on the digital display and that now works.
In the process of trying to start it one thing I discovered was that if it didn't start on the first key turn then it likely wouldn't, but to remedy that I pulled the fuel relay and it fires up until the fuel runs out.
I tried that back and forth a couple times until I get it going.
So it appears that it wants to flood it on the start cycle.
Also, when it was running I pulled the plug on the idle air control and the idle stepped way up and it burned a bit cleaner, so am I right in thinking that disconecting the plug allows the valve to open and allow more air which in turn improves the mix and speeds up the idle speed?
When it reached operating temp and I assume went to closed loop it did step down the rpm a bit as would be expected.
So, why is this running so rich?
I also notice that the fuel pressure gauge bounces back and forth between about 52 and 60 when running, would this be normal.
And on a side note, my son read in a post that if he wanted to see if it was leaking in the plenum to pull the hockey puck thing under the vortec sheild and he could look in, he did that and there is no way to look in just another mechanism for the butterfly under the plenum, and now there is no way to know if that is open or closed. Does the plenum have to come off again?
If it does then I'll leave that until I hear back from someone about the fuel problem.
At least when running the engine sounds like it's in good shape with lots of spunk.
Old 03-16-2010, 06:59 PM   #18
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Take it to a mechanic and let him deal with it!
Old 03-16-2010, 08:26 PM   #19
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Angry Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by Ajvdub
Take it to a mechanic and let him deal with it!
Well gee, that was very helpfull, why didn't I think of that?
Maybe because I been working on heavy equipment, diesel,rebuilding engines, and restoring antique cars for 40 years and I bought this damned GM product for a hobby project to give to my son's girlfriend so she can get to work and didn't want to spend a fortune having some halfass in a shop throw $2000 in parts and labor at it trying to figure out what is wrong and that joining this forum would bring me help and support like the other ones I belong to and give my help and support to.
Guess I'll have to deal with this on my own.
Old 03-16-2010, 10:12 PM   #20
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by Ajvdub
Take it to a mechanic and let him deal with it!
Was just reading your 93 Sonoma rant.
Old 03-16-2010, 10:39 PM   #21
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Didja ever TEST the CTS? Hows the fuel pressure look when you turn the key to run? Does it come up and bleed off?
Old 03-17-2010, 08:14 AM   #22
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by lesterl
Didja ever TEST the CTS? Hows the fuel pressure look when you turn the key to run? Does it come up and bleed off?
New CTS, fuel spikes to 60-62 then drops to 54.
Bleeds off after hour to 30 psi.
Old 03-17-2010, 10:34 AM   #23
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by tspivak
Well gee, that was very helpfull, why didn't I think of that?
Maybe because I been working on heavy equipment, diesel,rebuilding engines, and restoring antique cars for 40 years and I bought this damned GM product for a hobby project to give to my son's girlfriend so she can get to work and didn't want to spend a fortune having some halfass in a shop throw $2000 in parts and labor at it trying to figure out what is wrong and that joining this forum would bring me help and support like the other ones I belong to and give my help and support to.
Guess I'll have to deal with this on my own.
Sorry I didnt know your experience (foot in mouth)

Just seems like you might be at the point where its not worth spending your time on it anymore.

As for me, I got the truck knowing it needed some work, just not as extensive on the front suspension. But I have fairly limited knowledge on cars. I have rebuilt the 460 Ford in my boat and wrenched on Mustangs in the past, my first job was pulling out and reinstalling transmissions but thats about it. It sounds like you have a ghost not letting your CPI run.

I'm sorry for the comment, I didnt mean to offend you.
Old 03-17-2010, 03:22 PM   #24
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by Ajvdub
Sorry I didnt know your experience (foot in mouth)

Just seems like you might be at the point where its not worth spending your time on it anymore.

As for me, I got the truck knowing it needed some work, just not as extensive on the front suspension. But I have fairly limited knowledge on cars. I have rebuilt the 460 Ford in my boat and wrenched on Mustangs in the past, my first job was pulling out and reinstalling transmissions but thats about it. It sounds like you have a ghost not letting your CPI run.

I'm sorry for the comment, I didnt mean to offend you.
On the contrary, the vehical is worth spending time on, it's rust free, fully loaded Tahoe, everything works(except egine at this point).
I did not buy it with anything other than an expectation to have to spend time getting it running, it's just that I have seldom run into a vehicle that has so many interdependent items that have to be all working right or nothing works.
Also, I have so many times run into glib and smarta** individuals on forums that I suppose I have little patience with them.
Accepted, and good luck with your ride, my son has one as well and it has a few gremlins in it.
Old 03-17-2010, 04:41 PM   #25
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Re: 93 Blazer 4.3 Vortec CPI won't start.

That is why I decided to invest money into mine, its a fully loaded Noma SLE, CPI, 4x4, power everything, a/c, ext cab, etc. so I dont mind as much, just feel like I'm throwing the dice with the high miles (167k) and its all original. The motor runs great and trans shifts sharp, 4x4 works great and no howling from the axles. And my comment was not meant to be glib, I just didnt know your expertise and simply recommended what I would do. Again, sorry and I wish I could help.
Old 03-17-2010, 05:51 PM   #26
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Hey Lesterl !

Your repeated response on the CTS got me thimking again about it.
A few years back I had a problem with a 92 Chev 350 TBI in a van.
Excessive fuel consumtion, and running dogish.
Replace the CTS and no more problem, however it always started.
So I rethunk about this and looking at the schematic decided to test the wire circuit.
Bad wire, fixed it, took at couple trys to get it going, I suppose the ECM needed to think about it's new situation a bit, then BAM, fires right up.
Now it still needs some fine tuning for sure and since the exhaust is leaking bad at the manifold pipe connection it sounds like shit anyway. but otherwise A OK.
I am surprised that this one sensor could have such a negative effect on the engine.
Thanks to all for their input, sometimes it a help just to have these ideas put in front of you again.
This didn't turn out to be a money pit because the only items I replaced were things that needed to be done on a vehicle this age anyway.
Still have to put the hockey puck back where it belongs but that will mean taking the plenum off again I guess.
No big deal.
Old 03-17-2010, 09:58 PM   #27
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Re: 93 Blazer 4.3 Vortec CPI won't start.

The CTS tells the ECM what the coolant temperature is and the ECM Chooses a fuel mix based upon the value. I have seen 'em not fire at all because the sensor was gone, wiring is always a good thing to look at too!

Hockey puck? You mean the IMTV?

Fix the exhaust leaks especially if they are before the O2 or near it if after - these leaks will cause the O2 to read lean and cause a poor warm running condition. At 135* signal from CTS the ECM goes Closed loop mode and starts reading from the O2 sensor to fine tune the mix.

Good luck.
Old 03-17-2010, 10:08 PM   #28
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by lesterl
The CTS tells the ECM what the coolant temperature is and the ECM Chooses a fuel mix based upon the value. I have seen 'em not fire at all because the sensor was gone, wiring is always a good thing to look at too!

Hockey puck? You mean the IMTV?

Fix the exhaust leaks especially if they are before the O2 or near it if after - these leaks will cause the O2 to read lean and cause a poor warm running condition. At 135* signal from CTS the ECM goes Closed loop mode and starts reading from the O2 sensor to fine tune the mix.

Good luck.
The IMTV was removed by my son, he had read a post saying that he could look down in the plenum to see if it was wet.
When he pryed it up the black part on the top came off and there was a machined flange part sticking up with the shaft for the valve in the center.
He realiozed that he was in trouble and left me to it, but I can't figure how anyone could look in here.
Did part of it stick in place, the shaft turns 180 degrees so I have nom way of knowing where to index it, should I just take the plenum off and reinstall with the valve in closed position?
I can't find detailed info on this anywhere.

Last edited by tspivak; 03-17-2010 at 10:10 PM.
Old 03-18-2010, 04:51 PM   #29
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Should have said 360 degrees.
Old 03-18-2010, 06:00 PM   #30
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by tspivak
Should have said 360 degrees.
So do you have any idea what the IMTV actually does?

Is it running fine without it?
Old 03-18-2010, 06:55 PM   #31
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Re: 93 Blazer 4.3 Vortec CPI won't start.

It adjusts the length of the intake runners, longer for low end torque and shorter for high end horsepower. It will run without it, but may not be at top performance. I don't know what effects it has when not operating or installed.

I made a short video of removing it and its actuation, I'll upload it soon so you can have an idea of how it's supposed to be installed.
Old 03-18-2010, 08:25 PM   #32
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by almighty4wd
It adjusts the length of the intake runners, longer for low end torque and shorter for high end horsepower. It will run without it, but may not be at top performance. I don't know what effects it has when not operating or installed.

I made a short video of removing it and its actuation, I'll upload it soon so you can have an idea of how it's supposed to be installed.
Man, that would be super apppreciated because I have been able to find no referance to it anywhere on the net.
Yes I did know what it is supposed to do, but since I haven't had this thing out on the road either before or after the starting problem I have no referance to know whether it causes a problem when not hooked up properly.
Obvoiusly it must have been put there for a reason, and since there are so many little things that can cause major problems(CTS for example) it would be better in my opinion to have back on the way it is supposed to be.
Thanks for the replies by the way!

Last edited by tspivak; 03-18-2010 at 08:28 PM.
Old 03-18-2010, 08:55 PM   #33
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by tspivak
Man, that would be super apppreciated because I have been able to find no referance to it anywhere on the net.
Yes I did know what it is supposed to do, but since I haven't had this thing out on the road either before or after the starting problem I have no referance to know whether it causes a problem when not hooked up properly.
Obvoiusly it must have been put there for a reason, and since there are so many little things that can cause major problems(CTS for example) it would be better in my opinion to have back on the way it is supposed to be.
Thanks for the replies by the way!
Yeah that makes sense. I am just curious because I have a goofy idle/stumble/timing issue on my CPI. I know this is one thing that has no data on it and thought maybe I could replace it and fix a problem. I'm following this because I too have discovered all the little quirks of the CPI engines.

Just looking for info....not trying to jack your thread.
Old 03-18-2010, 09:09 PM   #34
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Re: 93 Blazer 4.3 Vortec CPI won't start.

You will have a weak point in your RPM range you didnt remember from before. My brothers quit on him and it was kinda weird but it ran ok, IDR if it set a SES.
Old 03-18-2010, 09:21 PM   #35
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by 93_Deuce
Yeah that makes sense. I am just curious because I have a goofy idle/stumble/timing issue on my CPI. I know this is one thing that has no data on it and thought maybe I could replace it and fix a problem. I'm following this because I too have discovered all the little quirks of the CPI engines.

Just looking for info....not trying to jack your thread.
That's fine, my son has the same thing on his 93 S10 TBI we can't get rid of the stumble at idle when it goes closed loop, and missing between 45-60 mph.
Replaced just about everything over the last year.
Only does it when it warms up.
Old 03-18-2010, 10:49 PM   #36
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Check for small cracks in the exhaust before and near the O2 sensor.
Old 03-18-2010, 11:13 PM   #37
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by lesterl
Check for small cracks in the exhaust before and near the O2 sensor.
Brand new exhaust complete front to back with new O2 sensor.
Odd thing was we put in a new dist. complete, and it ran fine for about 3 days then back to the stumble.
Old 03-19-2010, 02:02 PM   #38
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Re: 93 Blazer 4.3 Vortec CPI won't start.

http://s111.photobucket.com/albums/n...=VIDEO0009.flv

s10forum doesn't allow embedded video links do they?

Anyways, here's the video. I had just unbolted it to look in, as my truck is idling at 2500rpm. What CPI engine doesn't have issues?
Old 03-19-2010, 02:58 PM   #39
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by lesterl
Check for small cracks in the exhaust before and near the O2 sensor.
I have an exhaust leak at the header gasket (replacing this weekend).

Other than that it's all new (only 10,000miles) headers, custom y, cat, and muffler. No leaks whatsoever.

Any other ideas!
Old 03-19-2010, 04:04 PM   #40
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by almighty4wd
http://s111.photobucket.com/albums/n...=VIDEO0009.flv

s10forum doesn't allow embedded video links do they?

Anyways, here's the video. I had just unbolted it to look in, as my truck is idling at 2500rpm. What CPI engine doesn't have issues?
Well, thats not how mine came apart, my son had to pry it up and the metal part and the electronics separated.
I think the metal part is oxidized to the plenum.
And now I would have no idea how much tension to have on the spring.
I think I'll just go to the scrap yard and get one.
Save myself the agony.
taking the plenum off isn't bad once you've done it.
Thanks a million, I can't believe you went to the trouble of doing this for me.
I owe you a draft.
Old 03-19-2010, 06:26 PM   #41
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Haha, next time I'm down south (everything is south from me) I'll take you up on that!
Old 03-19-2010, 07:44 PM   #42
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Ha! depends where you are Hum Montana.
I'm just nort of the 45 parallel.
Next I'm repairing exhaust and working on the missfire.
Oil dipstick tube is rusted off flush.
I can't pull it so I'm thinking about driving it in and putting a couple earth magnets on the pan bottom.
The magnets would hold it in place, I tested this on another oil pan.
Question is, whats just below the tube hole in the pan, would there be anything in the way of it dropping to the bottom?
Old 03-23-2010, 12:03 PM   #43
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Re: 93 Blazer 4.3 Vortec CPI won't start.

I had very similar problem with mine, a 93 Jimmy, after changing the ingnition module, everything was ok !!
It append 2 years ago and still good !
Old 03-25-2010, 11:38 PM   #44
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Tspivak, did you ever resolve this?
Old 03-26-2010, 08:40 AM   #45
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by Ajvdub
Tspivak, did you ever resolve this?
Yes, lesterl made a point of looking at the cts and although it had been replaced I decided to dig deeper and found bad wiring.
Fixed that and it fired right up after a bit of choking and coughing.
next I will fix exhaust leak and try to get it running smooth.
Check previous posts.
I have a dipstick tube problem.
Old 04-06-2010, 10:42 PM   #46
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Re: 93 Blazer 4.3 Vortec CPI won't start.

I am having almost the exact same issue and I suspect that the intermittent ignition and fuel pump prime might have something to do with a bad or failing ignition switch. Is this possible in your case? I've been down this road before and it can be such a PITA! My 95 is no start dead in the driveway also and I will troubleshoot every inch of it tomorrow. I was burning out 1st and 2nd gear on a test run 24hrs ago and now dead. 60 PSI at the test port and holds overnight almost within a few psi. The ignition is where I am focusing next. I haven't pulled the plenum but less than 50k km ago I did a brand new spider, regulator, etc. When putting an inspection camera through the TB butterfly I can't see any leaks...

A.









Quote: Originally Posted by tspivak
Okay, this thing still won't run.
I've had the plenum off can can see no leaks under pressure .
I replace coil,ignition module,rotor,cap,wires plugs,taken off egr to verifiy it's clean and working,cleaned sensors,checked conections,changed fuel tank(it was leaking0, changed pump and pulsator(big name for a piece of hose), sock on pickup,disconected and blew out lines and checked for leaks,new filter,oil change,oil filter,new GOOD battery,fresh fuel.
Althought it did relucktently fire up and run yesterday, it will not restart today.
Compression varies from 140 to 150.
Distributor is correctly timed.
Fuel pressure is no different no than before I changed pump and does not leak down at what I would think to be an unreasonable rate.
Priming with ether makes little or no difference.
The new plugs are now covered with black residue and I will change out
again this week when time allows.
What the heckis going on with this money pit?
Old 04-07-2010, 02:43 AM   #47
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Re: 93 Blazer 4.3 Vortec CPI won't start.

I fixed mine. Corroded ground wire, was killing the power to the pcm. Problem fixed.


It's the damned simplest things sometimes. I knew it would be too.
Old 04-09-2010, 11:10 PM   #48
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Re: 93 Blazer 4.3 Vortec CPI won't start.

where was the ground if you don't mind me asking?

Glad you got it fixed. I tore the intake off this morning and there's some fuel washing in there but I can't see any leaks. The pressure doesn't hold (gauge must have stuck first time!). I sprayed water/dishsoap suds all over the connections from the spider and couldn't find any damn leaks. When I crimp the return line I don't notice a drop on the tank side so I assume the pump holds pressure.... It drops under 50 in maybe 15min at the test port. I might try UV dye for s&g! I have an 'old' spider assy that I will try. It can't be that damn tricky. I didn't want to buy another new spider however....

A.
Old 04-10-2010, 08:49 PM   #49
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by neex
I have an 'old' spider assy that I will try. It can't be that damn tricky. I didn't want to buy another new spider however....

yeah sounds like it's either fuel lines or regulator swap time or spider and all basically while you're in there


getting ready to do mine soon as the rest of my parts arrive
Old 04-11-2010, 03:34 PM   #50
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Re: 93 Blazer 4.3 Vortec CPI won't start.

Quote: Originally Posted by Sound Barrier
yeah sounds like it's either fuel lines or regulator swap time or spider and all basically while you're in there


getting ready to do mine soon as the rest of my parts arrive
It was cleaner than I thought under the plenum but there was a little gas on the reg side. I pulled the reg and swapped in another, replaced a popet clip, buttoned it all back up. Did the fuel filter and pump ground. She sits at 61 PSI now and holds over 58 for an hour. We went from a no start to being able to break the tires free at 50k. It passes all scan tests and my LTFT numbers are finally in line!

I couldn't believe the difference the pump ground and new filter made. I just did the filter over a year ago and I swear there was basically black/grey 'clay' coming out of the old one. Geeeeesh.

The beast loves on...

A.
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