Engine/Transmission (1998.5 - 2002) High fuel pressure......sometimes

[JVackiner]

I have intermittent "high" fuel pressure. I run an Airtex pump otherwise everything is stock/OEM. Normal is around 18psi as read by two Westach electric gauges (pre and post filter). Sometimes the pressure will rise to 30psi and stay there, other times it will bounce around between 18 and 30. The gauges always move in tandem. I can't seem to pin down any constant that will make it rise. Is there something in the VP44 (original at 297K) that could be causing a restriction at times. Any ideas? Thanks in advance.

 

[mhenon]

Might be the fuel guage or isolator. Nothing in your system should make 30psi.

 

[SAronson]

Might be the fuel guage or isolator. Nothing in your system should make 30psi.

He has TWO ELECTRIC gauges... . no isolator :-laf, and they're reading the same output. I'm thinking maybe the problem is electrical, and not mechanical. I would look at the connections/ wiring first... then mechanical issues. 30psi... yikes!

 

[FourBarR]

There is a relief valve on the return line to the tank. its on the vp-44 looks like a banjo bolt . could be sticking I think its set at 14psi. hope this helps.

 

[BSeyler]

I'd take a look at the relief valve, also. I have the Airtex on my 99. When I change filters, I always crack a fitting, bump the starter, and wait for the air to be pushed out. Last summer, I got in a hurry and forgot to crack the fitting first. It pressured up fine and I started it up. Fuel pressure went to 0 and it died. I worked with it, trying to get pressure for quite a while. It would show on the gauge for a few seconds and then show 0. It finally started and pressure went over 20. Each time I shut it off and re-started, the pressure would show 0 and work up to over 20. Then, it would come down to around 17. Over the course of a couple of days and about 1500 miles (road trip), it straightened out. It has not missed a beat since. The relief valve is the only thing I can think that might have caused my problem. Good luck.



Bud

 

[mhenon]

He has TWO ELECTRIC gauges... . no isolator :-laf, and they're reading the same output. I'm thinking maybe the problem is electrical, and not mechanical. I would look at the connections/ wiring first... then mechanical issues. 30psi... yikes!

Guess I should have read his post better. All my problems with erratic fuel pressure have been the gauge (or isolator in my case). Still don't see where you're getting 30psi out of a LP putting out 18psi. If the Airtex is internally bypassed (and even capable of 30psi) I suppose that could be plugged up.

Nothing in the VP44, bad relief valve or not, would cause your LP to suddenly put more psi than it's capable of.

Mike

 

[JVackiner]

In the past when I had electrical problems it would read 0psi and it was always the power wire to the gauges coming loose. I will trace the wires though, not tough to do.



The relief valve sounds likely. If it is sticky or plugging up, can it be taken out and cleaned?



It seems to me that if a lift pump will free flow at basically 0psi then the more "resistance" you add down flow (line length/size, fittings, filter, valves) the more the pressure will go up. I guess I don't know what the upper pressure limit is on the airtex.



I will look for it first chance I get. Tomorrow I get to fire up the N14 Cummins :-laf and go after a load of fuel.



BSeyler: From NAPA I got a brass fitting like a tire valve. When I change filters, I just hold it open with a phillips screwdriver to get the air out. Don't have to crack any fittings that way. It screws into the tee fitting I used to mount one of the sending units.