Engine/Transmission (1998.5 - 2002) Replaced lift pump, but now loosing pressure

[Sticks]

Bad grounds can cause issues as well. ECM may be fine, but a flaky ground can cause a voltage drop.

We have a member here that has installed a 12v cam and installed a mechanical LP and has the same problem, even with all new fuel system from the pickup tube to the overflow valve on the VP.

 

[hcole]

Have still been fighting erratic fuel pressure even after installing ddrp. Eventually it got to where it would actually run on a vacuum. So this definetly proves why people need to have fuel pressure gauges installed. A dodge diesel will run no problem with no fuel pump running. Got the 0230 code and started doing some research on here. Got it narrowed down to ECM. I found a post by Jlandry showing how to wire a relay to get the supply voltage out of the ECM. At this time I have it wired through a toggle switch, which I wouldn't recommend because someone might forget to turn it off or on. I have one that lights up when it is on and it is mounted next to my gauge. As I read all the many many posts on here about people having erratic pressure I wonder if the ECM was just giving erratic voltage. Looking back now I don't think there was anything wrong with the last two pumps I bought. Each time I would turn the key off and restart I could get a different pressure. Lately I would have to cycle the key on and off 4 or 5 times. The only way to test would be to hook up a voltmeter permanetly and drive around monitoring it for days. Mine wouldn't always act up so I never really caught on to what was happening until it finally went to 0 volts. All I know is 2 airtex and one ddrp were all giving erratic pressures but not now with their own circuit. This is with 100% all new components in the fuel system, completely aftermarket from draw straw to filter and replaced overflow valve. All along it was electrical. At least I got some good experience and learned a lot about the fuel system. By the way I also kept an airtex mounted and ready to go so I have 2 fuel systems that I can control from the cab so I will feel pretty confident on the next trip. Hope this helps somebody figure theirs out.

I had this problem last year with my intank pump. It was low and erratic. I bought a holley blue? (I think) and installed it on the frame below the tank and put a relay from the battery to the pump and used the fuse under the hood for the VP44 to trigger the relay. So, now I turn on the ignition and you immediately hear the pump running and building pressure. Both intank and Holley pumps run and I have 10-12 lbs. pressure ALL the time. The relay is mounted next to the fusebox under the hood for easy access.

 

[CEdwards]

Put on new vp-44, took out fuel heater and thoroughly cleaned filter housing. Replaced return line completely and now fuel pressure is rock steady at 14 to 15 psi no matter how I drive. Don't know if return line could be the cause or what but runs better than ever with new blue chip pump with new computer. After spending close to $3000 on fuel system and doing all the work myself, It finally runs right and my frustration is over.