Good afternoon, I put a titanium fass lift pump along with a Fleece sureflo sending unit on my 2001 pickup about a year and a half ago. It’s been flawless for a few thousand miles. I had been noticing some slow starts when warm. Not bad just a few more revolutions than what was normal. I put some NAPA cross referenced fuel filters on because I didn’t have FASS replacements and didn’t have the time to wait . I started to take a trip recently and fuel pressure dropped significantly. I got the truck home and parked it for a month . I wasn’t real confident about the NAPA filters so i replaced with the direct replacement FASS filters. Test drove the truck for an hour or so and all seemed fine. Today it did the same thing again. I had gotten 17-19 psi at idle and 15-17 WOT. Today it dropped to 15 idle and drops significantly at WOT.

I talked to tech support at FASS and he mentioned something about a valve in the VP 44 might be a problem. Now when I turn the key on PSI jumps to 17 and drops to zero momentarily when I start the pick up. I’m in the process of putting a mechanical gauge in line to verify that the brand new auto meter pillar gauges are not the problem. Does this sound like a VP44 problem? Truck only has a 160000 miles, but I assume VP44 and everything beyond is original equipment .

Thanks, Kevin

Edited December 29, 2025Dec 29 by kbf98520

2 hours ago, Mopar1973Man said:

Just a flag or marker there is another error. Use an actual OBDII code reader.

I had a scan gauge on a power stroke. It worked well. Can you suggest one for this pickup.

3 hours ago, Mopar1973Man said:

Just a flag or marker there is another error. Use an actual OBDII code reader.

Can you recommend one? I’ve been meaning to get a quadzilla . Does that have code reading? Or maybe just a basic code reader for now?

Edited Monday at 05:02 AM2 days by kbf98520

Then 2 things.

Quadzilla only programs a running truck. There is the ability to see live data that's about it.

OBDII code reader like OBDLink MX would be a good option.

On 1/4/2026 at 9:45 AM, Tractorman said:

So, it sounds like the lift pump relay was not the issue? Symptoms remain the same?

• John

That’s right, same symptoms after 100 miles or so and it seems I’m starting to get the not answer the phone/ not call back run around game on the lifetime warranty from FASS as it now seems to be an electrical issue in pump, best I can tell.

1 hour ago, Mopar1973Man said:

OBDII code reader like OBDLink MX would be a good option.

Just ordered one. Unfortunately, I have to go back to work and I won’t be able to get back on this with the code reader until February.

Edited Monday at 05:53 PM2 days by kbf98520

It seemed like I might have had another bad relay , so I jumped it, pressures were all over the place, from 20 to 12psi varying rpm’s. I did another bucket test had a constant 15-16 psi for an hour. Hooked the pump back to the truck, keyed it on psi went to 20 briefly while the truck warmed up then psi was all over the place 20 to 12…. FASS is leaning heavily towards OFV in VP 44. IDK

12 hours ago, kbf98520 said:

I did another bucket test had a constant 15-16 psi for an hour. Hooked the pump back to the truck, keyed it on psi went to 20 briefly while the truck warmed up then psi was all over the place 20 to 12….

Give details of your bucket test. Have you ran the engine while drawing fuel from the bucket with a separate power source to the lift pump?

I'm having a hard time with believing it to be a VP44 overflow valve problem. Did the FASS representative explain with detail on exactly how an VP44 overflow valve problem would adversely affect lift pump pressure?

Also, if there is a restriction in the fuel supply anywhere in the lift pump circuit (especially the suction side), then unpredictable fuel pressure could be expected.

What it the GPH rating on your lift pump?

• John

Edited yesterday at 06:07 PM1 day by Tractorman

2 hours ago, Tractorman said:

Give details of your bucket test. Have you ran the engine while drawing fuel from the bucket with a separate power source to the lift pump?

I'm having a hard time with believing it to be a VP44 overflow valve problem. Did the FASS representative explain with detail on exactly how an VP44 overflow valve problem would adversely affect lift pump pressure?

Also, if there is a restriction in the fuel supply anywhere in the lift pump circuit (especially the suction side), then unpredictable fuel pressure could be expected.

What it the GPH rating on your lift pump?

• John

It’s a Titanium Series 100 hog. It was an isolated bucket test, did not run the engine from bucket.

Unfortunately I have to leave the truck for a month or so will not be able to do anything

100 GPH. Spellcheck got me

7 hours ago, kbf98520 said:

Unfortunately I have to leave the truck for a month or so will not be able to do anything

It will give you time to clear your mind and come up with a good diagnostic approach.

Possible issues to keep in mind:

• intermittent fuel supply blockage, especially suction side of lift pump

• large amount of air in fuel system (not likely)

• intermittent power to lift pump

• faulty lift pump (pressure regulator issue)

When things get difficult to diagnose for me, I change tactics and try to prove what is working CORRECTLY, not what is working INCORRECTLY - a process of elimination. This method will sometimes get the issue resolved sooner than focusing on things that one might think is wrong.

• John