S-10 Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
I have a 92 S15 Jimmy that will not start - fuel problem. Before I go out
and buy a brand new CPI Spider (or junk the Jimmy) I thought I would see if
any one could provide me with a method to actually check that the CPI itself
is functioning.
Right now I have the upper manifold off. I have a 60psi fuel pressure
reading. Prior to actualling buying a pressue gauge, I tried to "shotgun"
the problem (changed fuel pump and fuel filter). Tried to "hotwire"
injector using a battery charger, saw no fuel coming out of poppet. Bought a
used CPI on Ebay (came without the poppets - had to swap in old ones). Again
tried to "hotwire" CPI, plenty of "clicking" but no spray.

Could I have fried CPIs by hotwiring? Do the poppets actually need to have
intake vacuum to spray (i.e. do I really need to put everything back together
and try to start it)? Has anyone actually seen the poppets spray either by
"hotwiring" or by letting the ECM do it?
Thanks
 

·
Registered
Joined
·
7,471 Posts
There is no could i have fried it, if you hot wired it it is most likely fried. Those a saturate and hold injectors, you need to reduce the current as soon as they open or they're toast
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #5 ·
j894 said:
I got a working spare if you want it. Just needs a new FPR ($50)
Thank you, I may still take you up on the offer. But, I just bought another used CPI on Ebay (boy this is getting expensive). I have read so much on the web about the Vortec CPI. I just wish I could find a sure fire method for testing it. I am not even sure if I would see the gas being sprayed as it must be such a tiny amout. I even brought home a power supply from work in order to check a suggestion from another forum in which the writer said that initially 4 amps is used to fire the injector followed by 1 Amp to hold it open. Although the first few times I did this there was a drop in pressure (charging poppet lines?) after that nothing but steady 58 PSI with plenty of clicking from the injector. Still hoping that someone who has done this testing before will read this post and provide an answer. My next experiment (If my wife doesn't kill me first) will be to remove one of the poppets / injector lines from the CPI body and see if at least the injector is opening when I give it the juice.
 

·
Unregistered User
Joined
·
3,591 Posts
Do you mean while its pressurized with fuel?
If not you wont see anything, the injector is like one big tbi injector.



Do you still want it, if you ordered a new one?
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 · (Edited)
j894 said:
Do you mean while its pressurized with fuel?
If not you wont see anything, the injector is like one big tbi injector.
Do you still want it, if you ordered a new one?
This is my current setup -
If I have attached my picture correctly you should see that the CPI is connected to the 2 fuel lines and that the poppets / lines are not inserted into their manifold holes. The pressure gauge is also reading about 60psi. Yes, I would appreciate getting the injector. I have sent you a personal message using this site (I hope it got to you) detailing my contact information. I could then re-sell the complete CPI that I just bought back on Ebay IMG_0421 (Custom).JPG . Thank you
 

·
Unregistered User
Joined
·
3,591 Posts
Was I was saying was... if you have the poppet off, unless you have fuel, you wont see much. Picture above showing the face of the acual injector. (asumming you were attempting to check the injectorfor "something" dry)

I got your message
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #9 ·
Finally fixed it -
Bought another used CPI on Ebay and did not try to test it with a power supply or battery charger.
Instead I installed it (hooked up fuel lines and electrical connector) and left all the poppets out (so that they were visible). With the coil - distributor cable grounded, I cranked the engine. First a couple of poppets sprayed. Next time, a ouple more. Next time, all six poppets sprayed.

Lesson learned - don't "test" without knowing exactly what you are dealing with.

I believe I screwed up the first injector that I bought by "testing" it.
Also, after putting everything back together, it still wouldn't start (what a terrible feeling). Engine fired with starting fluid but wouldn't run (what no fuel delivery again?). Since I had seen the poppets spray before I put it all back together, I began moving the wires to the CPI while cranking and it started. Moved the wires at the external CPI connector and it died. Seems that I had an intermitant open right at the connector / wires. Was this the problem in the first place? We'll never know. Cut out connector and spliced the wires together and no more problems.

Bottom line - the poppets will visibly spray (even without the upper plenum being put back on) if everything is working right. Thanks
 

·
now XTREME
Joined
·
1,888 Posts
just v-8 the bitch rather than junkin her
 

·
Registered
Joined
·
5 Posts
I hope your e-mail is connected to this thread as I have the very same problem.

Could you send me a photo of the location of the shorted wires. I havent started with the CPI yet. The engine when seems to run when it is in the right temperature range, drove it into the garage last week when it was warm. Today its not starting. Have 40 PSI at the fuel pressure port, and engine starts for 5 seconds when I pour in an oz of fuel.

So I'm guessing its the injectors. Any help from someone who's been there would be appreciated.

Thanks,
 

·
Got Fuel Rails?
Joined
·
4,539 Posts
I hope your e-mail is connected to this thread as I have the very same problem.

Could you send me a photo of the location of the shorted wires. I havent started with the CPI yet. The engine when seems to run when it is in the right temperature range, drove it into the garage last week when it was warm. Today its not starting. Have 40 PSI at the fuel pressure port, and engine starts for 5 seconds when I pour in an oz of fuel.

So I'm guessing its the injectors. Any help from someone who's been there would be appreciated.

Thanks,
40psi isn't nearly enough, needs around 60psi.
 

·
Registered
Joined
·
5 Posts
40psi isn't nearly enough, needs around 60psi.
rat,

Thank you for the reply. Bought the fuel pump cheap on e-bay for about $110, guess I keep asking for these problems. It ran for about 300 mi before it dropped to 40 psi. Thought this pressure was sufficient...(My providing this would have probably been useful info in first post.)

I'm not looking forward to pulling the tank again and am considering just putting an in line pump on the fuel lines. Did this successfully 12 yrs ago on my 89' S-15. Any problem leaving the original fuel pump in? As long as the in-line is capable of 60 psi, I think a Push - pull configuration should be ok???
 
1 - 15 of 15 Posts
Top