98 Chev Silverado 1500 5.7/4WD (Original motor was a 5.0 - I put in a 5.7 30K ago when the old motor had a cracked head ... but I think the fuel systems are the same)

First off the truck as 160K and the fuel pump was replaced 20K ago. Mr current problem started last week. I left for home and the engine stalled about a block away and would restart. I pushed it home and it restarted about an hour later, and ran fine for a couple of days. I had no problems prior to this.

Today it would not start. I replaced the fuel filter and it still won't start. When I turn the key, I can here the fuel pump priming, so I don't think that's the problem.

Any thoughts?

Do the basics you need fuel ,air ,compression, spark and at the right time . One is missing.Test and post back.
LIFE IS SHORT GO FISH

Thanks. The truck won't drive so I'm trying to get a friend to check for any trouble codes.

My gut tell me it's not getting fuel. (If I was getting fuel, but no spark, would I smell gas at some point when cranking the motor?) If the fuel pump works and fuel filter is new, where might the problem be.

Replacing the fuel filter didn't fix the problem, but it needed to be replaced anyway. I'll check for spark and compression tomorrow. Assuming fuel is the problem, where would you start. I'm willing to waste some time on guesses before I have it towed.

Here's a tip to speed things up . With air filter off.CAREFULLY give the eng a short spray of starting fluid(parts house) while helper cranks eng. If eng tries to start you can assume that spark ,compression and timing are good enough to run ,post back with results. P/S Check all fuses.
LIFE IS SHORT GO FISH

Grant; In addition to re-tired suggestions; These Vortec motors demand at least 55psi fuel pressure to run. You can try cycling the ignition two or three times. Each time you cycle the key, it will build pressure. Turn the key to the 'ON' position, wait about five seconds, then turn it off. Wait another five seconds, turn the key to the ON position again for five seconds. Do this two or three times. If it then starts, it more than likely a faulty fuel pump. A pressure guage will be needed to confirm. If it turns out to be the fuel pump, use only factory (GM) replacement. The aftermarket pumps just don't last. BTDT.
Loren
SW WA

Re-tired.

I began a late night process to check some of the things you suggested. I gave it a crank just for the heck of it and I heard a sputter. I cranked it again, it started! The motor struggled for about 5 seconds and then went into normal cold weather idle (its about 40 degrees).

I let the motor idle for about two minutes and then took it for a drive. I added 12 oz. of Gumout fuel injector cleaner to the approx. 10 gallons in the tank (I don't know how much that helps). In all, the engine ran normally as I drove it for about 45 minutes, including a few highway miles. As of now, it's starting and running great.

Thanks for your help. I'll post again if problems recur. After I replaced the fuel filter, I was confident that I had cranked the engine enough to get the fuel flowing all the way to the motor. Perhaps I didn't crank long enough. Actually, I'm hoping that's the case.

Loren, I took me a moment to figure out BTDT.

I didn't read you comments until after the problems "fixed" itself. I may well never have had the need to post here if I has followed your steps to build up fuel pressure. (See comment to Re-tired above).

Knock on wood ... the fuel filter was the original problem, and I simply errored when trying to start it after the filter was replaced.

I'm 90% sure the replacement pump I have is GM/OE. I was out of town when it happened. A mechanic I knew, who had grown up in the town I was stranded in, recommended the local mechanic who put in the new pump. He was actually adamant about using OE. Unless he pulled a switcharoo on me, the current pump is GM.

Thanks for your advice.


(This post was edited by grant8218 on Oct 27, 2009, 12:06 PM)

grant; The key cycling trick isn't a fix. But, if it works after several trials, then you will be looking at replacing the pump. Sorry.
Loren
SW WA

Loren, I drove the truck yesterday and this moring with know problems. I'm more confident know the my orginal problem was the fuel filter. The problem I had after I replaced the filter is that I didn't crank the engine enough to get fuel flowing all the way to the engine.

While your tip was meant to compensate for a failing fuel pump, I think it would have helped with the situation that I had.

grant; You are correct. If it was just after replacing the filter, then that trick would have helped. I always do that after I've replaced a filter. Also, you can check for leaks before the engine actually starts, too. Glad to hear that you aren't having any more problems.
Loren
SW WA

I think you will find that it is basically impossible for a fuel filter to be the sole cause of a "no start" in that truck. This is a high pressure, high flow system. It pumps about 10 gallons of fuel to consume a pint. The rest returns to the tank. What happens when the filters get restricted is they work the pump much harder until it eventually gets too weak to overcome the restriction. Changing the filter temporarily relieves some resistance so a weakened pump will seem OK temporarily but the problem will likely come back.




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Excellent explanation, HT. Unfortunately for the vehicle owner, I'm afraid that you are correct. Got that crystal ball out again?
Loren
SW WA

Well, it ran for three days. Now the problem is back. Is the fuel pump shot?

You need to confirm that by testing the fuel pressure but that would be the expectation.




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