Starting Problem/Fuel Pressure problem

[screaminsho]

Hi All,
A starting problem prompted me to check fuel pressure, i connected a schrader valve and gauge on the fuel rail, from what i understand; when the key is turned forward (not starting)there should be fuel pressure, mine has 0 lbs, after cranking excessively it starts and has 30 lbs of pressure at idle, when i gas it from idle there's 40 lbs of pressure, then i shut the car off and the fuel pressure drops to 0 lbs again, but the system should maintain fuel pressure. What should happen during all these procedures? Am i right? Wrong? How much pressure? Please help.
Thanks.

 

[projectSHO89]

When the key is first turned on, the pump should run for about 1.5 seconds. You can usually hear the pump run if you listen for it.

This interval is to pre-prime the fuel system under pressure.

The service manual has a complete procedure for dignosing pressure leakdown.

How long does it take to leak down? The spec allows for only a little bit in three minutes. Any faster would indicate a problem in one of several areas: fuel pump, return line check valve, fuel pressure regulator, or a leaky injector. External leaks would be obvious due to fuel odor.

Your pressures don't sound too bad, especially since you probably didn't follow the manual's procedure.

Steve

 

[screaminsho]

How long does it take to leak down?

Instantly to 0psi

What procedure? I thought upon turning the key the pressure goes right up. Somewhere i thought i read that the pressure should be at 39psi

When i turn the key off, drops instantly to 0psi

I thought the system stayed full of pressure

 

[projectSHO89]

It is supposed to stay at or near full pressure. Yours is broken. See the service manual for the diagnostic procedure.

The manual's test procedure says to check the pressure with the FP pin of the Self Test Connector grounded. This is the static fuel pressure and should read 39 +/- 2 psi.

The short initial pump priming cycle when the key is first turned on may or may not provide adequate static pressurization. That is why the service procedure requires continuous activation of the fuel pump.

Once the static pressure has been measured and found to be in spec, remove the ground lead and watch the pressure guage for three minutes. the static pressure should remain within 2 psi. If it does not, there is a leak in either the return line check valve, the FP regulator, injectors, fuel pump, or lines.

If these tests pass, perform the engine on test. Disconnect and plug the vacuum line tot he FP regulator. Start engine and run at idle. FP should be around 30 psi or so. If not, fuel filter restricted, FP regulator problem, fuel line restricted, power loss to FP, or FP.

High speed test: as above, rapidly accelerate engine and watch guage. Pressure should remain within 5 psi of starting pressure. If not one of the items in the previous step is at fault.

Freebie (doesn't cost anything to test): Pull the vac line to the FPR and see if there is gas in it. If so, the FPR diaphram has ruptured.

Steve

<small>[ June 02, 2003, 08:52 AM: Message edited by: projectSHO89 ]</small>