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4.3 TBI V6 Rough Running Problems and Solutions

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Old 07-03-2006, 05:38 PM   #1
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4.3 TBI V6 Rough Running Problems and Solutions

First off! I've done alot of research here and found plenty of info to get my truck running as good as possible so far..

I have an 89 S15 4x4 4.3 262 V6 TBI The truck was running rough idling bad and blowing a white/blue smoke.

I did some reading on the TBI so I took the carb apart and cleaned out the vacum lines (some where packed with carbon) After assembling everything the idle improve dramatically. I can't really tell but I think one injector is leaking as it seems fine drips occassionally drop directly downward from the injector. I will replace both soon, but am wondering if there is some other way to easily tell that an injector is leaking.

About a year ago I noticed the oil had gotten white and foamy on the dipstick when it got low. I immediately did an engine flush, oil change and added some stop leak to the rad since then there has been no indication of water in the oil.

I decided to change the wires/cap/rotor, and plugs when i did this i noticed the #1 cylinder (front left) spark plug was carboned up bad and most likely fouled. After replacing the plugs the truck ran great for about 2-3days and then the plug fouled again? Since the truck is blowing blue smoke I am assuming there is oil leaking into that cylinder causing the plug to foul and blue smoke to blow out the exhaust. (There ias also alot of condensation/water coming from the tailpipe) The radiator fluid has dropped very little in a year so I don't think any water is getting in. I then did a compression check and the #1 cylinder is about 120psi and the rear are running around 135-140 (150 is what it should be) So now I am down to a leaky valve seal or bad ring and wanting to tell which before i dig into the motor.

I tried searching but could not find too much on doing a valve job. seals on the 4.3? if anyone has any links or helpful info for someone in my position (never done this before) it would be greatly appreciated. FYI-I am mechanically inclined as I have a motorcyle shop and tear down 4-strokers all the time so hopefully this will be like a bike with more parts...

CHEERS
Old 07-04-2006, 11:09 AM   #2
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

Quote: Originally Posted by flip49
(There ias also alot of condensation/water coming from the tailpipe)

CHEERS
Well water is suposed to be one of the bi-products of combustion gases after it passes through the Catalyst. so the water is normal. If the tail pipe was constaintly blowin white smoke, then i would be worried about the coolant getting into the combustion chanber
Old 04-18-2007, 01:44 AM   #3
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

I have the same problem, with the same plug. I'm thinking of doing the valve seals. any in put......
Old 04-18-2007, 02:25 AM   #4
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

i believe that the injector drip is normal
Old 04-18-2007, 09:47 PM   #5
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

Quote: Originally Posted by 91GMC's
i believe that the injector drip is normal
that is not normal. a conical spray pattern is normal, I would replace both of them w/refurbs that can be bought pretty cheap($25). I would also look into the EGR being stuck they can carbon up pretty bad. cat can also be a problem on high mileage trucks.been there done that.
how many miles on the truck. 150 psi would be a best case for a TBI engine compression. If I remember correctly a TBI engine has a 9 or 9.5 compression ratio.
as for your oil problem how much is the engine using (qt/3K) or is it not really noticeable. chances are you valve stem seals are done and also your rings depending on mileage.
two thing for you to have a look at- Injectors- Linder Technical Services - Home of the "Injector Guru" and if you want to give this a try Auto-Rx Engine Cleaner I've used it in 2 vehicles and like it little $$.
good luck you shouldn't have any trouble w/opening up your engine if you work on bikes.
Old 05-04-2007, 11:31 PM   #6
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

I end up changing the valve seals, it was a bitch, but got it done. changed all the wires , cap, roter, and plugs. change the oil and filter ( oil valvolen max life 10w 30w ) the truck has only 162,000 k on it. 98 4.3 its like its NEW!!!!!!!
Old 05-05-2007, 10:04 AM   #7
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

I may have read a little deaper into your situation, but Valve stem seals will not increase compression on that cylinder. The seal are above the valve face.

Some condensation is normal as stated above.

How many miles are on your truck. With it fouling that plug in a few days it sounds like to mee you have a ring problem. If that is the case, I would not worry about replacing the valve seals. They would be easier to replace while you have the engine apart. If anything if your truck is highmileage than the seals leaking is proabaly a god thing to keep the rings lubed better to kepp higher compression. I just sold my 95 silverado (350 TBI) w/250,000 miles on it. It used 1 qt of oil every 5,000 miles. I also used 20-50 oil & it had a very slight rear main leak. I still got 19 mpg out of it too.

Just my .02
Old 12-05-2009, 05:02 PM   #8
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

I have the same problem. How hard is it to replace the the rings? I have never done them before. I was thinking about just getting another motor for it, but would it be cheaper and easyer to just put the new rings in?I only have 147,xxx miles on the motor, but its going through about 3 qts of oil with in a few weeks.
Old 12-05-2009, 05:26 PM   #9
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

You need to do a wet compression test on that cylinder to determine if it needs new rings or new valve guides. You also need to connect a vacuum gauge and run some simple tests.
Check this link:
http://www.secondchancegarage.com/public/186.cfm
There isn't any way anybody can help you over the internet untill you post the results. Also, you will not be able to run the necessary testing after you pull that head.

Question: is oil leaking down on that #1 spark plug?

If oil leaks down on the plug it will evetually end up on the ekectrode and foul out.
Old 12-05-2009, 05:34 PM   #10
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

"added some stop leak to the rad" FTMFL
Old 12-06-2009, 09:48 PM   #11
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Re: 4.3 TBI V6 Rough Running Problems and Solutions

Drop a teaspoon full of oil in the cylinder and re run the compression test, if it comes up rings are bad. If it doesnt then you have a head/ HG issue.

Rering kit at Autozone can be had for around $200 (includes rings, bearings, gaskets)
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