Quote:
Originally Posted by reefgeorge
Fuel pump is Delphi. Pressures (all at stand still) after the replacement were:
61 psi at 2 second prime
56 psi after 5 min leak down
56 psi after start
Distr/rotor/wires/plugs all new and all AC Delco. Just got the special tool for the PITA #3 plug and will do that last one this weekend.
Fuel filter is new
Air filter is 4k miles
I'll get a spark tester on the ignition wires and see how much energy I have.
What are the first things to go - ignition switch, MAF sensor, ignition module, coil, injectors, crank position sensor, etc.?
Thanks,
George
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To many things to chose from.
Proper testing first before throwing parts at it.
I would get it on a good engine capable scanner and check for codes and all sensor readings for up to par.
Watch and check for missfires.
Post back any codes.
Fuel pressure may be low or fading out after on road running or spark getting weak someplace.
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.
And run a full fuel pressure test