What is Normal Fuel Pump Pressure

[newt]

Dear All, I have had intermittent problems with warm starting where my 95 Explorer XLT won't start for 1/2 hour to 2 hours and this has been going on more frequently. From looking at the posts I know that this is often a symptom of a dying fuel pump. I have replaced the fuel pump relay as well as the ECT sensor. When I checked fuel pressure, it was 32 PSI with vacuum and 42 PSI without vacuum. This is barely above minimums listed in Chilton's. From what I have read in these forums 32 is quite low and is a sign of a dying fuel pump. What is the Fuel Pressure that may cause the intermittent start problems or any problems?

Thanks, Newt

 

[96eb96]

Dear All, I have had intermittent problems with warm starting where my 95 Explorer XLT won't start for 1/2 hour to 2 hours and this has been going on more frequently. From looking at the posts I know that this is often a symptom of a dying fuel pump. I have replaced the fuel pump relay as well as the ECT sensor. When I checked fuel pressure, it was 32 PSI with vacuum and 42 PSI without vacuum. This is barely above minimums listed in Chilton's. From what I have read in these forums 32 is quite low and is a sign of a dying fuel pump. What is the Fuel Pressure that may cause the intermittent start problems or any problems?

Thanks, Newt

I would investigate the Idle air control valve. Especially if it is the original one. You can try carefully cleaning it with throttle body cleaner, but its probably on its last leg. It is the cylinder on the intake with two wires and two screws. Common problem across the ford line. The fuel pressures you wrote sound acceptable. Here is a TSB specifically for your year, but any ford that has an IAC can have this issue.

http://www.ford-trucks.com/tsb/fulltext/show_article.php?tsb=97-9-5

 

[newt]

Thanks, I just did clean the IAC, MAF and replaced the ECT and ACT as well as the Fuel pump, PCM, and EEC Power Relays. I haven't driven enough to have the problem happen again. I am driving currently with a fuel pressure gauge just in case the problem happens again. Any test that can find out whether the IAC is still good? Thanks

By the way, I looked at the referenced TSB. What does having the engine "soak" for 1 - 4 hours mean?

 

[96eb96]

Thanks, I just did clean the IAC, MAF and replaced the ECT and ACT as well as the Fuel pump, PCM, and EEC Power Relays. I haven't driven enough to have the problem happen again. I am driving currently with a fuel pressure gauge just in case the problem happens again. Any test that can find out whether the IAC is still good? Thanks

The test is your car starts up and never stalls! When was the last time you changed your fuel filter? You didn't mention it. It could be clogged and restricting flow.

 

[newt]

Sorry, Fuel filter was changed about 3 thousand miles ago.

 

[96eb96]

Thanks, I just did clean the IAC, MAF and replaced the ECT and ACT as well as the Fuel pump, PCM, and EEC Power Relays. I haven't driven enough to have the problem happen again. I am driving currently with a fuel pressure gauge just in case the problem happens again. Any test that can find out whether the IAC is still good? Thanks

By the way, I looked at the referenced TSB. What does having the engine "soak" for 1 - 4 hours mean?

I believe it means sitting without running...like you park at 8 am and use the vehicle again at 10am.

 

[newt]

The engine has the intermittent no starts for .5 - 2 hours after stopping, usually for gas or a convienence store on either long or short trips. Will try a new IAC. It is cheaper than a new truck. I have taken this problem to three places including Ford. All have no idea and the car runs fine when they get it. Ford was the least useful, not wanting to do anything without a diagnostic code or running any diagnostic tests e.g. Fuel Pressure check or voltage checks.

 

[96eb96]

If you changed all those parts AND you have no driveability issues after you start up I would have to suspect the IAC. You may not see the problem for a while if its clean.

The OHV engines have some intake gasket issues but I don't think that would affect starting. There would be rough idle when it starts up.

The only thing I can think of now is the pump wiring having resistance and delivering lower voltage to the pump. This can be checked out.

 

[96eb96]

The engine has the intermittent no starts for .5 - 2 hours after stopping, usually for gas or a convienence store on either long or short trips. Will try a new IAC. It is cheaper than a new truck. I have taken this problem to three places including Ford. All have no idea and the car runs fine when they get it. Ford was the least useful, not wanting to do anything without a diagnostic code or running any diagnostic tests e.g. Fuel Pressure check or voltage checks.

Again, that sounds exactly like the tsb. The IAC may have been the only culprit the entire time . I would swap it ASAP.

 

[fo5lvo]

fuel pressure 98-01 5.0L Explorer/Mountaineer

I'm trying to find the correct (Ford spec) rail-pressure for the last generation of 5.0L Windsor (Explorer and Mountaineer, 1998-2001)

related: is this a vacuum-modulated pressure? - or just constant pressure?

Can't find any info in the miserable Ford Technical Service Manuals

First engine problem after 13k miles on EEC-V 5.0L conversion (peppy 85 Volvo wagon) - second Volvo conversion in progress - same series engine, with a little extra stroke & attention to porting on Ford's nasty GT-40P heads

Thanks all

 

[newt]

Chiltons listing for fuel pump pressure

The pressures listed in chilton's, at idle, are 30 to 45 psi with vacuum connected, 40 to 50 psi with vacuum disconnected, fuel system hold pressure after five minutes 30 to 65 psi and max fuel pressure anytime 65 psi for all engines that the manual covers including the 5.0L. I don't know that it definitely is vacuum regulated but... follow the fuel lines to the fuel pressure regulator and if there is a vacuum line running to it, it is. It wasn't hard to find in my 4.0L 95 Expl.