I bought my truck (first time diesel owner) a few weeks ago. From the information I gleaned from this site I knew some gauges were in order. A call to diesel manor brought a fp gauge (mechanical with isolator) and egt to my door. I was a little leary about drilling the manifold pre turbo without removing anything but I did it and all is well. On the other hand upon starting the truck the fp gauge climbed to 15 psi and then dropped down to 0. I guess that I am glad to have installed the gauge to find this problem before it wasted the injection pump. Thanks again to DTR for all the good info.

 

Hmmm...I don't think the engine would run with 0 psi. You might need to borrow another gauge and test to make sure you don't have a problem with your new setup.

 

I am going to spend some time going over the set up. I just took the line off the regulator and bumped the starter and got a good flow from it. I finished the install last night and didnt have the time to go over all of it. Might still be some air in the supply line. Maybe I posted too soon. I was expecting the worst.

 

That's fine...let us know what you find out, 'cause we're all learning!

 

When someone (me - oops) installed the 1/8 line from the regulator to the gauge tightened the fitting a little to aggressively and stretched the compression fitting. Hence it would initially register up to 15psi than drop to "0" as the pressure bled off. I guess all that working out after Christmas did do me some good....or in this case bad. I sprayed the fittings with soapy water yesterday while the truck was running and it did not bubble so I didnt think it was the fittings. All is well. Happy now.

 

The engine will run when the lift pump is not putting out any pressure if it is a vp-44 I dont think the cp3 trucks will run on 0 psi, I could be wrong though.

 

The truck will run with zero pressure. Even at WOT with a comp it will run with 0psi.

 

And pulling a heavy trailer, sometimes for a few thousand miles.

 

The truck will run with a fuel pressure reading of zero (if plumbed ahead of the Injection pump) due to the fact that the IP has a small fuel pump built in.
The Lift/Transfer Pump's job is to supply enough fuel to keep the IP properly fed, and an overabundance of fuel to keep the IP cool.
The excess/warmed fuel is sent back to the fuel tank via the return line.

 

Vp will run with 0 psi, but it should NOT be pulling a vacuum.

If you have positive FP, then the VP is getting all the fuel it can handle.

If there's any kind of vacuum present, that's bad for the VP-- VERY bad.