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Originally Posted by mike2004tct
'97 Blazer, 68k miles.
No raw gas smell, or visible leaks.
Starts OK when warm.
Fuel pressure readings;
Cold, sitting for more than 17 hours, key off = 0 psi
Turn key on, no start = 30 psi, then drops to 0 psi within 5 seconds of pump priming finish.
Pressure while cranking = 62 psi
Pressure when enging starts/idling = 54 psi
Pressure while driving between 30-45mph = 47 to 60 psi (60 under load, 47 at steady speeds). Idling at stop = 54 psi.
Turn ignition off, pressure goes to 62 psi for 2 seconds, drops to 0 within 10 seconds.
Turn ignition on within 10 minutes of previous shut-off (no start), pressure = 62 psi.
Turn key off = stays at 60 psi for 2 seconds, drains to 0 in less than 10 seconds.
Opinions?
This is a 17 month old Delphi unit (the 3rd I've had in the truck), Fuel filter was changed with pump, about 10k miles ago.
Within the past 3 months, I've also replaced the VCM, distributor,coil, and ignition module(VCM burnt them all up). It's been a hard starter ever since the electrical problems began, and it getting worse (occassionally takes longer to start; 3 crank sessions at 10 seconds each before firing- Saturday, and Monday for instance, Sunday and today it started fine)
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Excellent job testing fuel pressure!!! Even when driving!
One additional driving-pressure test; pedal down test. This confirms that the vacuum-controlled FPR will respond to engine load. I don't know what the spec pressure is for this test, but I do know it has to be done to confirm proper FPR function.
Also you might have to note the pressure differences between idle with vacuum OFF of FPR, and idle with vacuum ON FPR. Again, I don't know what the spec difference should be - check the Chevy shop book...