Question: Rookie C4 Owner

[5horseman]

I just aquired a 1990 C4 and it ran fine for the first few days. Suddenly, one evening while driving it began sputtering and every time I would press the gas it would backfire. I changed the fuel filter but it still seems like the fuel pump is going bad. While the fuel filter was off, I turned the key to the on and there was very little fuel upstream of the filter. Shouln't there be good pressure and plenty of fuel at that point?

 

[gmjunkie]

I just aquired a 1990 C4 and it ran fine for the first few days. Suddenly, one evening while driving it began sputtering and every time I would press the gas it would backfire. I changed the fuel filter but it still seems like the fuel pump is going bad. While the fuel filter was off, I turned the key to the on and there was very little fuel upstream of the filter. Shouln't there be good pressure and plenty of fuel at that point?

L98's should have 34-39 Lb fuel pressure,there is a schrader valve on the rt fuel rail to attach a fuel pressure gauge!

 

[5horseman]

Thanks for the info. Does this sound like a fuel pump issue to you?

 

[gmjunkie]

Thanks for the info. Does this sound like a fuel pump issue to you?

Yes,but could be other things too!!
Pressure needs to be checked!! Install gauge and turn on key,if the pressure isn't at 34-39 lb,the pump is probly bad!! If the pressure is with in specs,more testing is required!

PS Welcome to

 

[surfer93]

There is another possibility, if you been getting contaminents in the tank, then it could be your sock is clogged on the pump.

Only heard of this once, but I saw a pic of the sock and it was completely covered w/junk.

 

[bucket]

There is another possibility, if you been getting contaminents in the tank, then it could be your sock is clogged on the pump.

Only heard of this once, but I saw a pic of the sock and it was completely covered w/junk.

..
surfer,
i learned a while ago that mr. gmjunkie knows whats up wit corvettes..
listening to him is like free money..
other than that he is old and bald...lol

 

[5horseman]

Thanks for all your help.
I did change the fuel pump along with a new filter sock. This resolved the problem for about 1 hour, then the sputtering has started again. Not nearly as bad, but still sputtering.

 

[Toms007]

Well, the FP is a fairly easy replace, but I think you ought to listen to what Junkie has to say. Checking the fuel pressure and then go from there. Appears that you spent money on a FP and probably didn't need to.

 

[5horseman]

Well, the FP is a fairly easy replace, but I think you ought to listen to what Junkie has to say. Checking the fuel pressure and then go from there. Appears that you spent money on a FP and probably didn't need to.

Yeah, I believe your right. My next step will be as he said, to check psi and then go from there. Thanks again.

 

[Schrade]

I think you should have low 40's minimum fuel pressure.

Search my posts for static and dynamic fuel pressure tests, and youtube for reference vids, but NOT EXACT procedure. Follow procedure as I've posted...

 

[surfer93]

..
surfer,
i learned a while ago that mr. gmjunkie knows whats up wit corvettes..
listening to him is like free money..
other than that he is old and bald...lol

I never said do not listen, I just gave the OP something else to check.
So go take your medicine and relax.

 

[bucket]

I never said do not listen, I just gave the OP something else to check.
So go take your medicine and relax.

.................
dear surfer,
my coment was not directed at you nor was it intended to slight you in any way..
:cool

 

[gmjunkie]

I think you should have low 40's minimum fuel pressure.

Search my posts for static and dynamic fuel pressure tests, and youtube for reference vids, but NOT EXACT procedure. Follow procedure as I've posted...

L-98's 34-39 lb
LT1 and 4's 41-47 lb
I may be in the Mountains of Western North Carolina,but I can read and wright,
I've also read a couple service manuals cover to cover in my time!!

:L:L:L

 

[surfer93]

Bucket,
No problem, sounded like you were saying not to listen to me.

 

[Schrade]

Thanks for all your help.
I did change the fuel pump along with a new filter sock. This resolved the problem for about 1 hour, then the sputtering has started again. Not nearly as bad, but still sputtering.

I didn't see this... Why did you change the pump? What was the pressure it was pushing?

It worked for an hour because that's when the motor went closed loop, and the problem that was there before is still there. No problems are apparent in open loop. All problems mysteriously vanish like tax dollars, when the motor is open loop/cold (as it happens to be, right after a part gets replaced too yup, and we say, "That's what the problem was..." ).




(...NOT!)

 

[Schrade]

L-98's 34-39 lb
LT1 and 4's 41-47 lb
I may be in the Mountains of Western North Carolina,but I can read and wright,
I've also read a couple service manuals cover to cover in my time!!

:L:L:L

I kaNT reed gUd eether. spelcHEK maKs my cpu sMoK.