98 Chevy Won't Start

[LucyG]

98 Silverado will run for awhile, then it dies. I can hear the fuel pump working in the tank, changed the fuel filter.

I can get it to start if I pour a little gas into the engine, but it dies as soon as that is gone.

Help!

[patbeechermail]

If it starts when you pour in fuel then it is likely a fuel delivery problem. Your fuel pump may be running but not developing enough pressure. Get a loner pressure test kit from AUTOZONE and test your pressure. Go from there.

[LucyG]

What is the proper pressure before start, and when the engine is running?

[j cAT]

Originally Posted by LucyG

What is the proper pressure before start, and when the engine is running?

with the 5.7L engine it should be 60-68psi...with key on engine running,,,then when engine off key off should hold with in a few psi,,,if it drops rapidly then the fuel pump with your explaination may mean the fuel pump is defective,,,could be also bad electrical ,,but if the vehicle has over 150,ooomi it is usually the pump...and the pressure drops, or low..

only replace with the delphi pump....

airtek pumps should never be used...

replace the fuel filter and relay also as this will insure the new pump will not get damaged,,,make sure the ground point at the fuel pump on the frame rail is cleaned , and secure ,,,as this ground has been a problem..

[LucyG]

This moring the vehicle started so I put a pressure gage on the fuel line. The pressure was 60 psi. The vehicle ran fine for a good hour. I could not make it die again. After I turned the engine off the pressure held strong at 57 psi so no leaks.

I did change the fuel filter and added injector cleaner yesterday. Could that have been the problem, or should I investigate further.

[j cAT]

Originally Posted by LucyG

This moring the vehicle started so I put a pressure gage on the fuel line. The pressure was 60 psi. The vehicle ran fine for a good hour. I could not make it die again. After I turned the engine off the pressure held strong at 57 psi so no leaks.

I did change the fuel filter and added injector cleaner yesterday. Could that have been the problem, or should I investigate further.

all that sounds good ,,,it may be the fuel pump relay or the ground next to the fuel tank,,,

the thing is when it did not start what was the fuel pressure so when it dies again make sure this is checked...turn key to ignition on ,, no cranking and measure the pressure...if its 60 68 psi and does not start it is most likely another issue..

[patbeechermail]

Had a very similar problem with GMC Jimmy. Somedays it would start and somedays it wouldnt. problem was inconsistent. Check all the things above as stated. My specific problem turned out to be the ground. found that there was no local ground at pump. It went into the harness and grounded god knows where. spliced in a local chassis ground and problem never returned.

[MT-2500]

Originally Posted by patbeechermail

Had a very similar problem with GMC Jimmy. Somedays it would start and somedays it wouldnt. problem was inconsistent. Check all the things above as stated. My specific problem turned out to be the ground. found that there was no local ground at pump. It went into the harness and grounded god knows where. spliced in a local chassis ground and problem never returned.

Yes good ground and good voltage is one thing to test and check.
But you need to run a pressure test on the pump.
Not only just throw a gauge on it and check the pressure one time.
It needs to be checked on cold start and check engine running pressure warm and after it has run a hr. on the road.
Tape a fuel pressure gauge to outside mirrow or outside windshield and test on the road running cold and hot.
May take up to a hr running for some weak fuel pumps to start losing running pressure.

If a 5.7 engine.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
Most good strong have a direct fuel pressure rating of a 100-105 lbs.
But do not run the pump orer a few seconds at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.