I need to wire in a better relay for my fuel system.

I've replaced EVERYTHING in the fuel system, except the relay, and am still having problems. The truck drops to 6-7psi when the truck is idling or has been cruising for a while. As soon as I punch the throttle, the pressure jumps up to 13psi. The pressure stays there for quite a while before dropping back to 6-7psi. I just keep repeating the throttle punch to keep the pressure up. I was told my next step should be to address the crappy stock relay.

Please don't address the stock pump. I've replaced it twice and am having the same problem, so I know it's something else.

Can someone recommend a relay and provide a wiring schematic?

 

If you talking about the VP44 , there is a relay , but if your talking about your Lift pump , there is no relay , it is wired to the ECM and recieves pulse width signal from the ECM.

 

So there is no lift pump relay ... now I'm confused!

I just went out and checked the relay panel and there is a "fuel system relay" installed. What is this relay for?

If that's not the problem, can someone explain my fuel pressure problem?

 

I was having the same pressure problem as you...ended up dropping the fuel tank and cleaning the gunk out of it.

 

Pull the relay you found and see if the lift pump will cycle.

Just as easy to use the stock lift pump wiring to trigger a good quality relay and run the pump from that.

Jeff

 

The stock LP does not have a relay, the relay labeled "fuel system relay" is for the IP. The stock LP is powered from the ECM.
I have been following your posts on both sites. I would try a relay at this point. Trigger it from the stock LP wiring.

 

I had the same problem as you. I replaced the pump and thought it was a voltage problem so I wired a relay direct from the battery triggered by the factory wiring guess what same problem. Get a big line kit or a FASS.

 

I've got the 1/2" big line kit with LP relocated to the frame, new in-tank module, new overflow valve, new VP. Everything in the fuel system is new, so it has to be electrical. I noticed today that when I'm running my AC I don't have the problem ... maybe that's coincidence.

This has been happening on two new pumps, so it's not the pump. They can't have exactly the same problem ... and before someone chimes in with the "electric versus mechanical gauge" theory, the pump changes tone when the pressure changes, so you're out of luck with that one!

I have figured out the main problem ... I bought a Dodge! If this is the best they can do, they can keep it! I wouldn't use this POS as an anchor for my boat ... it probably wouldn't do what it was supposed to do anyway ... totally worthless!

I apologize if anyone senses my frustration, but I've had enough!

 

Try another gauge on it and see what happens.

 

Ok, got the relay. Do I have to run the ground to the battery or can I connect the ground next to the relay? What's the pros and cons?

Edit: Forget the last, I wired the relay next to the battery.

How about an 18 gauge wire for the trigger, should that be enough?

 

Bump, anyone?

 

18 gauge for trigger will be fine

 

Good stuff!

I've got the relay wired up, now just to find time to install it ... maybe tomorrow night!

I really hope this works.

 

Cummins' decision to power the lift pump straight off the ecm is the source of the vast majority of lift pump and VP44 problems, in my opinion.

 

Well, Bart, I hope you're right ... I'll keep you updated!