Quote:
Originally Posted by MT-2500
97 is a bad year for ign switches.
Get a repair manual with wiring chart and check all 12 volt power and grounds to switch and out of switch.
Also check for good fuel pressure.
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.
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Thanks for the quick response. I forgot to mention that it's a v6 vortec, if that makes a difference.
In my mind, what seems to be happening is that the fuel gets starved out after so long. My combination of tricks to get it to start again is to remove the gas cap to relieve any back pressure and open the hood to cool. Not sure if this really helps or it's just coincidence.
The last 6-7 times it happened, the fuel tank indicator was below 1/8th of a tank left. Today I filled the tank to the brim, and it stayed on all day--so far.
I'll get back to you on all that pressure testing. There is a place to test it from the line only inches away from the throttle body, so i have to assume this is where it's normally tested. Is there another quick access area to check the pressure?