2nd Gen Non-Engine/Transmission Fuel guage all over the place

[JFulford]

Hello.

I bought a 2002 2500 Quad cab shortbed, Auto, 4wd with 76K on it about 4 months ago.

My friend and I have installed a Westach Fuel pressue guage, with the

hose off the schraeder valve.

I have also installed an Edge EZ on it(with EGT guages, post and pre).

When we first installed it(3 months ago), it seemed to work pretty well: 13-14psi at idle, 8-10 at WOT. Now I can be cruising at 35mph and it will drop and stay at 6psi unless I give it a little throttle, at which time it will jump

back up to 10-12psi. If I let off on the throttle(which I have barely touched

anyway) it will drop back to 6psi. At WOT it drops to around 6-8.

It doesn't always do it, and it doesn't seem to be heat related.

Is this a guage problem or is my lift pump giving up?

Jeff

-- email address removed --

2002 SLT SO QCSB 4. 10 Dana 60/70, 47RE, 4WD

 

[DieselRam30]

Is this a guage problem or is my lift pump giving up?

Could be either. Are you running the gauge with an isolator? Are you getting any codes from the truck? Have you changed the fuel filter recently? Is there a noticeable drop in performance?



You're at the very, very bottom of what is marginally acceptable (8 psi) in terms of pressure. Post back with some of this info, and we can probably help.

 

[R-N-R]

Hate to be a doomsayer, but 10:1 your LP is on it's way out.

 

[JFulford]

Fuel guage all over

Update/corrections: The pressure does drop to 6psi at idle(when off the pedal).

However, if I am on the pedal at all it will vary from 8-11psi.

I changed the fuel filter about 2 months ago(1000miles on it). The sending unit

is isolated from the engine on a mount attached to the battery holddowns.

The truck is showing no codes at all(snapon MT2500) and, overall, seems to be running fine.

My mileage is a bit lower than I had hoped(14. 8-15 in town handfigured).

It is just kind of strange that it goes back up to 12psi when I accelerate.

My friend is now on his second injector pump(first one in warranty) at 145K.

He put a guage on after the first one and never saw less that 6psi under any conditions. His new lift pump is running 14 and down to 10-11 at WOT.

That's what I'm worried about. Could just change out the LP now I guess.

Thanks

jeff

-- email address removed --

 

[nps]

Sounds strange. Suspect the gauge sender, providing you have it properly grounded.



Westach gauges have been reported as having erratic behavior if the gauge and sender are not grounded to the same point. Many will wire the gauge to the sender and the sender to ground. This is not good.



Wire the gauge to a ground point, and the sender to the same ground point. Both get a dedicated wire running to the same ground This eliminates the chance of a loop in the ground to cause erratic readings.

 

[Michael Hughes]

I am the friend that helped Jeff install the gauges. The sending unit and the gauge are grounded at the same point.

 

[JFulford]

Well, Dodge warrantied my lift pump and installed/retrofitted the "intank"

replacement. In the process, they managed to break my fuel pressure guage hose. After receiving a new hose from Geno's, my pressure reads around 8-9psi

at idle and stays at 4psi at 3/4 throttle. Other than being lower than the

"failing" lift pump, it doesn't vary much at all.

My hand guage reads 9-11 at idle.

I also found out that the vp44 had been replaced at 70000 miles (previous owner didn't know what they had replaced. But no sign the lift pump was replaced at that time.