Turn the key, spikes the gauge....Start truck, stays at 15psi.......Then sometimes after couple min it drops off completeley.......Will never move agian!

Sgut truck off, restart and will do same!

Is this gauge related, or is my LP dieing?

No power loss at all.....????

Oh yea.......edit!

 

That sounds like more of a guage problem.

Check the wiring, make sure everything is secure and in the right place.

Then, if all else fails, give the manufacturer a ring.

I've heard that Autometer is pretty good with warranties and other problems.


phox

 

Phox...Its a mechanical gauge would that matter......Maybe the isolator?

 

Option 1... try it without the islolator.. (2) Autozone used to sell a miniture fuel gauge that would screw into the top of the F/F canister, same thread size. It would tell you for sure.

 

I had the same problem with my FP gauge a while back, nearly had a heart attack when I saw the pressure drop to zero. Turns out, the screws on the isolator had worked themselves loose and thus the no pressure reading. Worth checking anyway.
mishkaya

 

Hi all,

Just replaced lift pump (for the second time in 3 months) last night. Just like you were saying; at start the gauge read 15psi, then soon after it would drop to 3psi and under acceleration down to 0 or -1psi. The pressure would never go back to 15 until I stopped and restarted the truck. This cycle would then repeat. I confirmed my readings with a mechanical gauge, so I knew my electric gauge was OK. Since the pump was still under warranty, I let Cummins NW handle the repair. They, in accordance with all warranty issues, tested the entire system for all possible issues related to a pressure drop. It turns out the lift pump was probably defective right out of the box.

*Side Note* My problem started within a few weeks after the 1st pump (and injection pump) were installed. The initial drop was only to 7psi and then back up to normal. Slowly the pressure began to drop further and stay low longer. Because Cummins or Dodge or maybe even Bosch (yes, I even called Bosch and spoke with a tech.) has stated that 5psi is the minimum safe acceptable pressure, I had to wait until my pressure dropped to this level before seeking warranty replacement.

Good Luck

Ron R.

1999 QC 4x4, 3.55, Auto. 87,000 Miles

 

Hmmmmm better get that little gauge to screw in...

Just wondering.......How could a LP be defective but still push fuel to the gauge? When i originally hooked up my gauges, my LP was dead, dead, dead......My needle never moved and shortly after that, my VP-44 died...So who knows how long i had no fuel pressure. I know the VP-44 can pull fuel thru the bad LP (causing early failure), but it cant push fuel up to the gauge can it?>

 

You might bump the starter to get the LP to run without the engine and listen to it. If the LP isn't a even hum then you got problems. Most times you can hear a up/down speed change that has a grinding noise with it...

 

Nope cause the pressure gauge reads the pressure into the VP44. If there is no pressure the gauge wont read any. When the VP44 is pulling the fuel in, anything before the VP44 becomes a suction line. Only to maybe read pressure then would be on the return, but if its pulling fuel already, I doubt there would be anything to return to the tank, and tapping into the injectors lines.... I already asked that question a while back.

 

Mine did the same. I suspected the thin tubing with the dang! compression fittings so I screwed the gauge directly into the isolator. The pressure stayed up for the half hour that I let it idle. This proved to me that the problem was in the tubing between the isolator and the gauge.

I cut the tubing just behind the ferrules and tried again with new ferrules. Same thing. Did I mention that I hate compression fittings? There is a very narrow torque range that will create a tight seal - too loose and they leak, too tight and they leak.

On to Plan B. I drilled a 1/8 pipe plug to fit the tubing and filled the plug with epoxy. That worked great for about 2 weeks.

Plan C, not yet executed, is to swap out the 1/8" poly tubing for 1/4" and try again. I've had better luck with the 1/4" poly tubing when I also use the metal inserts and plastic ferrules so that's what I'm going to try.

Don

 

dkinzer....Ahhhh sounds logical.....When i get a chance i will try that as well....

 

They have to be otherwise they wouldnt be in business with how whacky their gauges are

When i called them up they insisted the calibration in my car was incorrect when i told them it has a 14.7psi fuel cutout due to a 2 bar map sensor and their boost gauge was reading about 18 psi before the fuel would cut out.. Finally i just said thanks for the help ill just throw away your gauge and hung up.