Re-posting from Saturday night due to server crash ....

In Feb 2005 I had to replace lift pump, vp44, apps, etc. due to LP Failure. Truck had 76K on it don't know when LP went out as per usual there were no symptoms until I had power loss and DTC codes but by then it was too late.

Several months ago I installed Di-Procol FP Guage with Isolator to monitor LP. Installed on output of FF.

Until this week things appeared to be fine.....

Ignition on: 14.5 psi for 2 sec's.
Start and Idle: 14.5 psi
Cruise: 12.5 psi
WOT Acceleration: 10-11 psi. (never went below 10).

Last Sunday (7/18) I noticed a slight instablity in the pressure reading at idle. Would flutuatate but the then settled down to what it had been (see above).

Thursday evening however I noticed that after startup and at idle the FP was 7.5 - 8 psi. Would crank back up to 12.5 for cruise and anything above 1100 rpm.

Still jumps to 14.5 with ignition on for 2 sec's and right after start but then drops to the 7.5 - 8 psi range.

Any suggestions or help would be appreciated. Am I having LP problems again, isolator, FF, ???

LP has only 9K on it and FF has about the same...

I've switched the gauge from the output to the input side of FF just in case but behaves the same.
I've ordered a FP Test Kit from Oregan Fuel Injection, should be here this week.

 

JEric, welcome to the forums! You may also want to check for air in the system. Sometimes a pocket of air before the VP44 will give the gauge an erratic reading.

 

Looks like your fuel pressure guage is doing it's job, letting you know the pressure's getting low so you can plan on a lift pump change. I use fuel conditioner on every fueling.

 

It isn't unheard of for an LP to go bad that quick.

 

I had one that was bad as soon as I drove it off the lot from having the previous one replaced.

 

Sounds like the lift pump to me. Had the same symptoms, a couple of times. My latest LP only lasted 4,000 miles. Hoesli Diesel replaced it, no questions asked. I would recommend you have your FP checked by a mechanic with a mechanical gauge, then you will know for sure. But I'd bet the farm that there's a new lift pump in your future. If it is under a year old, I could contact the supplier and see about warranty.

DeWain