darrenG

When I turn my truck off, I can watch the fuel pressure drop to zero in less than 5 seconds. I'm under the impression this isn't normal?

Dr. Evil

More importantly, what does it read at idle, cruise and WOT??

CTD NUT

That is normal.......when the lift pump shuts off, there is no longer any fuel flow and therefore, no pressure.

Mopar1973man

At shutdown my drops like a rock to 0 PSI. This is normal.

67HotRod

Same here.

Shovelhead

If you're using a needle valve on the Pressure line, you might need to crack it open just a touch more.

darrenG

I'm trying to figure out why after replacing the Lift Pump, crankshaft position sensor, all the fuel line from half a foot infront of the tank to the VP, replacing the VP itself and the check valve, i still have hard starts. Everything is chunking its prime fast. I don't find diesel fuel leaking from anywhere. This is an ellusive (and I'm willing to bet would have been cheap) fix but I can't find the pos.

I'm gonna replace all the stupid rubber washers and possibly the gasket on the ff housing. If that doesn't fix it, drop the tank and check everything there...and fix that stupid sender unit problem. If THAT doesn't fix it, this truck may be for sale or hitting a tree, whichever gets me the most $.

Shovelhead

Have you checked the return lines from the VP to the tank?
All it takes is a couple of hairline cracks to allow air to enter the fuel system and a loss of prime.

darrenG

no, i have not checked those. is there a recommended way to check for hairline cracks? I was under the impression the check-valve on the vp would shut, keeping it from losing pressure through the return line.

bmoeller

Being a '98.5, I'd suggest replacing the rubber fuel lines anyhow. You should've seen mine, when I installed new ones. They were SHOT! Return line was in the worst shape. Was starting to leak, and had one 3-4" crack in it, plus a few smaller ones. Truck runs MUCH smoother now.

darrenG

All the rubber line going to the lp and vp is changed, didn't bother changing the return line. Guess I'll track down where to buy that and replace it. hopefully this will fix it.