When I started my truck the first time with the new ECM the fuel pressure was at its normal range of 14-15psi. After I shut the truck off I replaced a wire on my switch box and accidentally knocked a wire from the fuel pump relay. When I started it again I noticed I had zero pressure. Thinking I could figure it out quickly, the truck ran out of fuel. Once it was sorted the truck obviously wouldn’t start. I loosened the fass filter and ran the pump until it gushed and then retightened. I then cracked 2 injectors and cranked until they bubbled out fuel. The truck runs but now it takes a a few extra seconds of cranking when cold to start and the fuel pressure gauge doesn’t read until a few seconds after it has started. My pressure is now at 18-19psi. The truck runs and drives fine, not sure what to do.

4 hours ago, Sycostang67 said:

The truck runs but now it takes a a few extra seconds of cranking when cold to start and the fuel pressure gauge doesn’t read until a few seconds after it has started.

It is likely that you still have air in the fuel system. Do you have an electric fuel pressure gauge? If so, is the sensor remotely mounted? If it is, then there will be trapped air in the line going to the remote mount. Eventually, this air will work itself out of the system.

• John

My sensor is mounted on the pump, but I imagine the line would still have to fill before any pressure was created. I do have a sensor closer to the VP but that had the Quad plugged into it which is no longer with us.

8 hours ago, Sycostang67 said:

When I started my truck the first time with the new ECM the fuel pressure was at its normal range of 14-15psi. After I shut the truck off I replaced a wire on my switch box and accidentally knocked a wire from the fuel pump relay. When I started it again I noticed I had zero pressure. Thinking I could figure it out quickly, the truck ran out of fuel.

If I am understanding correctly, the engine died because the lift pump was not operating. If this is true, then one of two things could be happening:

1. The engine died because the VP44 internal vane pump could not pull fuel through a non operational lift pump. Some lift pumps are built this way, others have a directional free flow when non operational.

2. The engine died because the VP44 internal vane pump was drawing air mixed with fuel from possible leaking fuel line / fuel line connections between the lift pump and the VP44 injection pump.

I would be more suspect of #2 since you are seeing it take awhile to build lift pump pressure after the engine starts.

I have actually installed a fuel line with a check valve that bypasses the lift pump just in case I have a lift pump failure. If a lift pump failure occurred on a road trip, the fuel supply would not be interrupted - the fuel would be drawn around the lift pump by the VP44's internal vane pump - no performance loss and no damage to the VP44. I could repair the truck when I get home.

• John

Edited yesterday at 03:40 AM1 day by Tractorman

I need to change the oil this weekend so I’ll crawl around underneath and see if I notice anything.