I replaced the VP44 injection pump last week along with the throttle position sensor and cam position sensor and now the truck won't idle. Every time you coast down to idle the engine dies! I have 13 psi at the inlet to the IP at idle or low RPM and this problem occurs whether or not my Edge is in the system or totally disconnected. However, once the engine dies it is much harder to start if the Edge isn't connected. Also, the Edge won't show 13 psi unless you crank the engine a few times and back off the key, but keep the lift pump running. A clear temporary fuel line from the tank to the IP verified no air was in the fuel lines.

Has anybody got any ideas as to the source of the idle problem??

Thanks!

 

it sounds like you have a fuel pressure issue.

 

x2 on the fuel pressure issue

 

Sorry to be gone so long, but I decided to put a new FASS LP in. We're sure the old LP caused the old IP to crash and burn even tho it was putting out 10 to 13 psi. The idle problem was solved by checking the TPS calibration which was good, but the throttle pedal had to be depressed 20 - 30 or more times to teach the ECM the throttle curve! After that the engine never died at idle again!

The higher pressures (up to 19 psi) of the new FASS LP caused a hard hot start as verified by disconnecting the new LP and starting the engine normally. So, I'll put a delay relay in ASAP to take care of the hard hot start!

Thanks for all the help everyone!