98 12v low fuel pressure
 

The fuel pressure at idle is about 7-10 which i know is real low but even when I get on it it drops right to 0 I can only get about 16-18 lbs boost on my 62mil turbo. The lift pump is new, the overflow valve is working correctly too. I tested the fuel pump in the tank by disconnecting the line from the lift pump. It started right up but no diesel came out of the supply line from the tank. Is this a tell tail sign of a bad fuel pump in the tank?

24v or 12v ... if its a 12v there is not a pump in tank that I'm aware of :humm:..

the 12V need 30 Psi to be a real nice runner ... Make sure also that your Idle is 895-950 @ Idle cold in gear ..:tu:

Its a 12v and there is really no pump in the tank. I guess i could check the filters in the tank they might be clogged up bad.

The filter is under the hood. Where are you taking your FP reading?

If the fuel lines have never been replaced, they are likely sucking air, which will lower fuel pressure. The rubber gets old.
Could also be the fuel heater, they can burn out and cause an air leak.
Mine was the braided steel line under the floor. It rubbed partly through on a cab seam.

all the fuel lines are new and the whole heater/prefilter setup has been bypassed which leads me to believe that either the filter in the tank needs to be cleaned or the new lift pump doesnt work.

Think I found the problem. The fuel tank module was so clogged i am surprised any fuel could get through. Going to buy and new module and sending unit and should be in business.

Good deal .. You also can drill out the factory unit and install a brass threaded plug and then install a BIO-Diesel hose and install a sock type filter on the end .. make sure its long enough to toutch the bottom of the tank ...

and you can oversize the pick up that way and get a bit more volume out of the Stock Lift Pump .. :tu:

I looked at the draw straws. I found the 96-97 fuel module for 190 bucks will it work for the 98?
More Information for CARTER R74699M

Well got my parts everything was put back together and its doing the same thing about 8-9 fuel pressure at idle and drops when in gear to 5-6 then to 0 when you get on it. Stalled out in the middle on the road up a hill by my house. Been reading that a worn out cam lobe could possibly be the problem here and it might explain why the new lift pump isnt keeping up. He used to run biodiesel through it which i guess doesnt help the cam lobe. Anybody have any thoughts on this and how can i test if the cam lobe is bad?