coryforsenate

iTrader: (1)

Hi all, I'm having suspicions it may be a fuel pump going out but would like other suggestions. I'm going to test the fuel pressure when I find a gauge.

So, occasionally the last 2-3 months my rpm's will go a little low sitting at a red light and sound like the engine is struggling to stay running but it's brief and quickly goes back to normal. However, this morning I cranked and it started up fine but then died a couple seconds later. It would stay on if I pushed the gas. After doing this 3-4 times, the engine stayed on and was fine when I started it up to go to lunch and heading back to work. It was pretty cold this morning, in the 30's.

Battery is good. TPS, IAC, EGR, MAF, MAP, coolant temp sensor, and fuel filter are new-ish and OEM. Could probably use a new air filter but I don't think that's the problem.

Vehicle is a Chevy '96 C1500 5.7L. I know it's not a car but there's a fair bit of overlap for this type of problem.

Any suggestions are appreciated!

LS6427

iTrader: (2)

How NEW is your MAF?

Symptoms sound like a dirty MAF.

Maybe a very dirty fuel filter......

Leaky fuel injector will slightly bog the engine down when idling........

.

coryforsenate

iTrader: (1)

Hi LS6427, the MAF is 3 years old. I haven't cleaned it in about a year so I'll grab my MAF spray and give it a try. It's an ACDelco OEM one.

Fuel filter is less than a year old. I change them every 1-2 years and the gas that comes out the pre-filter side is never very dirty.

LS6427

iTrader: (2)

Try cleaning the MAF...see if that solves it.

No codes showing, right? Maybe go get a free scan anyway.

.

coryforsenate

iTrader: (1)

Cleaning the MAF didn't make any difference this morning.

Actually, it was less reliable today. Died at a light.

The fuel pump is the original one, with 175,000 miles on it. Going to pick up a gauge today and check the fuel pressure.

Are there other possibilities? You mentioned the fuel injectors but accessing those is a big job on my vehicle.

I appreciate your help.

coryforsenate

iTrader: (1)

You know, I haven't check the fuel pump relay. Will check that too.

ghardester

Other than when it is dying at a light, how does it run when driving on the open road? Does it misfire or run sluggish? I think that you are on the right track looking a fuel supply. And you didn't really say if there are any engine codes. Even if you have the check engine light on all the time due to a known cause like removal of some pollution control stuff, there can still be other codes stored. Clear the codes and see what resets. My CEL is on because I have removed the AIR injection system and just haven't tuned them out yet. But the first thing I would do if I had a new problem was check for new codes.

If you are just getting shitty performance without misfires, keep looking at fuel supply issues.

coryforsenate

iTrader: (1)

Hi ghardester, I do have a CEL code but it's just the P0420 (catalytic converter at less than 95% efficiency) and P1406 (some carbon stuck in the EGR pintile, need to pull it off and clean it again). They've been coming on periodically for a long time and I don't really worry about them. I clean the EGR and reset the codes and it's fine for a while.

It drives fine on the highway, plenty of power and no stutters or anything. It only got really bad these last two mornings when I tried starting it in freezing temps. It would occasionally sputter a little before while sitting at a red light before but now it actually died at a light this morning. It won't die if I keep my foot on the gas.

There are no issues when I start it to go to lunch or when I start it to drive home, only these last two mornings. To check the relay, I swapped the fuel pump relay with the A/C relay and will see what happens tomorrow morning. Not sure if it's the cold or sitting for 12+ hours overnight. If I have the problem again I'll do the free rental of the fuel pressure kit from O'reilly's and check it.

coryforsenate

iTrader: (1)

So far, after changing the fuel pump relay switch I haven't had a problem. Would be awesome if it was such an easy fix. I did order and receive an ACDelco OEM fuel pump and strainer but even if the pump itself wasn't the problem I'll replace it some other time since it's the original 23yo pump.

I will update if the problem returns.

Darth_V8r

iTrader: (4)

Ok, operates good under load and poorly at idle sounds vacuum leakish. May be worth looking for cracked and oily vacuum lines - particularly pcv lines that suck in oil all the time.

coryforsenate

iTrader: (1)

Hi Darth_V8r, all the lines look good. I do get an EGR P1406 code periodically and need to pull it off and clean off the carbon but I don't think that's the problem.

I'm still having some problems, though not as bad as the engine dying, so since I have the fuel pump and sock in hand I'm going to go ahead and replace it and see if that clears it up.