Engine/Transmission (1998.5 - 2002) Bad gauge or lift pump?

[Big A]

I can't figure out if I've lost the lift pump. Saturday, pressure was good. I stopped for fuel. Topped it off. Took off down the road, I glanced at the gauge, and to my unpleasant surprise, 0psi. The readings are taken at the schrader valve. Within minutes The gauge was reading around 5psi. At idle, it would show about 10. My pressures have always been 15psi at idle, and around 8 or9 full throttle. The truck never missed a beat. I was away from home pulling my boat. The truck runs awesome. It started right up this morning. I even bumped the stater to see if I could hear the pump running, and it does. I put a new fuel filter in, and still very low pressure. Also, when i stopped for fuel again, I drained the fuel filter, Cycled the lift pump a couple of times, and the truck started right up. I'm kind of confused, any advice greatly apperciated.

Thanks

Big A

 

[RPyle]

Sounds similar to my experience when one of my many LPs pooped.

 

[CCOLLAR]

It could very well be the sender. I think it is pretty common for these to go belly up. I experienced a very similar situation with my first pressure sender, so installed a mechanical guage directly to the fuel filter canister, and the pressure was fine. I replaced the sender and haven't had any problems since.



I hope this helps.



Craig

 

[Ron Bissett]

Is sender mounted off the motor , when first turning on key switch do you observe the gauge to see it move from where it is and then moves to show psi for a few seconds then moves to zero psi ? And dose it move to show PSI when motor starts and runs at idle ,what is psi shown then You can get a T fitting and use a maniacal gauge to check at same time . Hope you find out is going on with system before going on the road. LOL Ron in Metro Louisville KY

 

[jbone]

Big A, just went thru that drill--replaced the lift pump, only to find the sender was faulty... . Called Westach and got their electronic sender and new guage--costly, but don't expect vibration to get this one!!! So hope to save in the long run... ... . R, J. B.

 

[Big A]

Jbone,

I have the westach gauge from Geno's. I talked to the dealer about it, and they're going to do a pressure test on the system.

Thank you all, for the replys, I'll keep you posted.

Thanx

Big A

 

[jhellmers]

One thing to check is the rubber seal gasket (o-ring) in the female schrader fitting. I found that after a while, the diesel softens the gasket to the point where it will collapse under pressure and give you a false reading. The gasket (o-ring) isn't compatable with diesel and it dissolves (softens) over time and can possibly give weird readings...

 

[Big A]

Well fellas,

It's official. The lift pump is toast. I took it to the dealer, and they determined that the pump is bad. They ordered a new one and will install tomorrow. I guess a fuel pressure gauge is a necessity in these trucks. I hope this new one will last.

Thanks again for all the advice

Big A