bad lift pump?
 

Just had my second lift pump in the last 5000 miles put in yesterday. The old one, when it was still working showed 15psi at idle and 11psi WOT. The new one is only pushing 12psi at idle and I can bring it down to 8psi WOT. Is there a problem with the new pump, or is this enough pressure to not cause a problem. Fuel filter has less than 5000 miles on it. Any suggestions?

What is the part number on the new pump?
A Carter?
I put a campaign 504 (p/n 4090046) pump on and am getting the same readings as your "new" pump. Mine is more like 9 WOT, but the idle is as low as your's.

You replaced a pump with absolutely nothing wrong with it.

No, the "old pump" lost pressure the other day. It would idle at 7-8 and then drop to 4psi under light throttle. Then a few minutes later would return to normal. And back and forth all day long. It was still under warranty so they replaced it for free.

Yes that would indicate that something screwey was going on with that pump.

Um, I did. [duhhh]
Someone here was reporting 18PSI ide, could drag it below 15 with the new LP's,

not the case with the one I got, it is junk.

I just replaced my dying LP with the "new and improved" campaign pump...11 psi at idle...8psi wot...what a dissappointment !

It must be a "God Smack" for getting a $65.00 pump that is supposed to be $170.00??

The flip side is, how do we know that this pump is not going to last 140K miles?

Ah hell, who am I kidding. :(

Is the FASS pump worth the extra money? I don't want to be replacing lift pumps every 3 months.

The "new and improved" pump was a freebie from the local Cummins dealer to replace the 3990105 / 4932707 pump I bought from them that lasted 1300 miles.

As far as longevity, I would say YES. The Fass II is covered by a 4 year warranty. :cool:

Absolutely, unless you like changing LP's. [dummy]

I'm planning on going with the Walbro pump conversion when my current pump goes toes up.
Just another alternative..... ;)

I was getting a drop in fp and loosened the fuel cap and all is well now. I must have a venting issue.

Walbro for me too. Too many stock lift pumps with poor pressure out of the box. Fass seems to have problems also and I'm concerned with parts availability when out in the sticks. I can change the stock or Walbro in a matter of minutes with it mounted back by the tank.