blakec3686

Hey everyone im hoping you all can give me some directon on what to look for. My dad just purchased a 91 c4 and so far its been running just fine. yesterday he found that after running it till it was warmed up and then shutting it off it was hard to re-start and would just crank over. he said after about 10 mins it started and sputtered for about 5 mins and then was fine but he could smell raw fuel and it was coming out of the tail pipe. do we have bad injectors? any ideas on what would cause this? i myself have an 81 thats been a great car for me but fuel injection is outside my knowledge base

Mr.Mouse

Had the same exact problem with a 1990 I had.
I changed the injectors and it ran like new again.

billschroeder5842

You need to check your coolant sensor as it may have gone bad on you.

If your engine thinks its cold, the computer will give it extra fuel until warm.

If your engine it warm and getting extra fuel, it will stall, sputter.... well you know.

Welcome to the forum!

blakec3686

Thanks for the fast replys! I was thinking something may be going on with the coolant sensor but my dad said at one point it sat for 2 hours an still wouldn't start but I still can't rule it out. I won't be able to really look at till hopefully this weekend, any easy way to check the injectors if the coolant sensor is good? Thanks again for all the help

antfarmer2

Pull the vacuum line off the FPR and smell for fuel there and check your oil for fuel too.

aklim

Easy way to check the CTS is to hit it with an infrared thermometer. Do it cold and till warm up. In the meantime, see what the ECM sees with a SCANNER and forget the gauge.

As to injectors, without a flow bench, you can pretty much make any SWAG you want. For the price, you can get a reman set that has been cleaned and tested so you know it flows in the right range. While you are there, the fuel pressure regulator is rubber and on an L98, I'd change it after all these years. You wouldn't trust a 20 year old condom so why not?

blakec3686

So turns out the fuel pressure relief valve is to blame. It's leaking into the vacuume line...., thanks for all the help everyone Thanh all very much. Parts will arrive next week

aklim

I'd do injectors and remove the TB and disassemble for cleaning.

antfarmer2