99 chevy express 5.7 when hot won't start

After running the van for aprox 1-2hrs and then I let it sit for aprox 10-15 min when i try to start it the gas guage goes past full to 3 o'clock and won't start. if i let it cool for aprox 2hrs it wil start. i've put 2 new fuel pumps and wiring harness. i have spark - 60-65 fuel pressure. i re-wired the connection for the electric up frt for the fuel pump. i've taken this to 3 different repair shops and they now can re-create it but can't figure it out. i have not taken to the dealer yet, and it doesn't happen when it gets cold outside. no eng codes. it will crank but no turn over. after it cools down it starts fine. please help. thank chris

At the time of no start take fuel pressure readings and check for good hot blue spark to all plugs.

If fuel gauge acts up when no start check all fuel pump and tank and gauge grounds.
And post back fuell pressure readings at time of no start.

just had van running for 3 hrs with dog house off so we can chk fuel pressure. the did re-start when we first shut off then when we let cool for aprox 20 min the gas guage went to 3 oclock would not start and fuel pressure was at 55psi. do you know what the voltage of the 2 wires that go to the coil from the computer?

Your fuel pressure is to low for a good start.
If the gauge acting up at the saeme time check all grounds on fuel pump and gauge and also have a look at the plugin of fuel pump wiring.



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.
But do not run the pump 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.

ok we final got a chk eng code po604. and now we do not have spark. once the van cools down it runs fine no miss fires or hesitation nothing just the gas guage goes to 3 o'oclock and wont turn over when the eng is hot. could there be a computer going bad and telling the van to go into safty mode and don't give spark?

computer/PCM/VCM code 604 is vcm ram memory / bad computer VCM.
There is no saftey mode.
It is bad when you get that code.
But feel luckie you got a code.
Computers do not often throw a bad computer code.
They usually Just go bad and do not say a word.
You might want to clear code and see if it returns.
If so replace the VCM and it will need reprogramed for you VAN.
Also do the fuel pressure test after the computer replace 55 lbs is way to low.