99 Cummins lift pump questions.

I just bought a 99 CTD and it had an occasional stutter in it like it was running out of fuel. Checked lift pump pressure, zero.

The pump is still on the side of the engine and it was making no noise so I bought an Airtex E7153 that is a direct fit.

As my luck would have it, no pumping from this either. Checked for power, none. I have it connected to a switched 12v source now and it makes 18 psi.

Questions are:

Where does the stock connector get it's power from? What are the chances it's something easy. I've read it get power directly from the ECM.

How much current do one of those gerotor pumps draw? If I have to leave it wired as is I need to have it fused accordingly. It is currently fused at 10 amps which is running it OK but seems a little light to me.

Kevin

Its powered from the Cummins ecu. Its possible that the ecu pump driver has failed. You need a fuel pressure gauge to be able to constantly monitor fuel pressure.

I was afraid of that. I have it on a switched circuit for now. I'll get it on it's own relay circuit shortly. Any idea how much current these pumps draw?

I have a gauge on the filter head now and it idles with 18 psi. It now pulls hard to the automatic WOT shift points on the 47RE. Not so much before.

I just bought the truck in Saskatchewan and I'm planning to stop on the way home at a truck wrecker to source a pyro, fuel and boost gauges.

Kevin

Electric fuel pumps don't generally draw much. I don't know how much this one in particular is, however on another install I used a high pressure electric fuel pump. The manufacturer supplied documentation showed the pump drawing 20 amps at max pressure. Max pressure was something like 150psi on an efi system that normally runs 50, which called for around 8amps. Your 10A fuse is probably fine. Bump it to 15 if you're concerned.



I would do the fuel pressure gauge, but for the rest, save your money. You'll be doing an injector pump soon...

What exactly "fails" on a VP44 anyway?

Kevin

Here's the way it was explained to me by the diesel mechanic the installed the VP44 on the 2001 Dodge Cummins I used to own.

The VP44 uses the diesel fuel to lubricate and cool it's self.

When the lift pump gets weak it doesn't keep the flow required to cool and lubricate the VP44 injection pump.
Hence it burns up/wears out.

He also said to never have less than 1/3 of a tank of fuel during the hotter months for essentially the same reason.
He said that since it's getting some hot fuel recycled back to the tank after lubricating/cooling the VP44 pump with less than that in the tank it's harder for the fuel to cool/lubricate the pump.

Is what he said absolutely true?
That's a good question, but it kinda makes sense to me.

But that's why I'm looking at 12 valve Cummins Dodge trucks right now rather than a 24 valve with the VP44 injection pump.

I found out when trying to replace and relocate the stock carter lift pump with a carter hi perf one meant for gas motors that the factory pump runs at around 9 volts, where the hi perf one runs at 12. My aftermarket pump would not run; had to get one made especially for the cummins. Best thing to do is to move the pump either real close to the tank or install one in the tank. The lift pumps, like any pump on a drag car, work better pushing, rather than pulling fuel. The shorter the distance they have to pull the fuel the longer they live.

I change my 05 to the Fast fuel pump/filter system and illuminated my stock in the tank fuel pump. You might need to call one of the companies that sell these systems.

I change my 05 to the Fast fuel pump/filter system and illuminated my stock in the tank fuel pump. You might need to call one of the companies that sell these systems.

When I first got my '01 Cummins back in 2011, I put a fuel pressure gauge on it almost immediately. The lift pump had 0 pressure...it had the dealer installed in-tank pump.
I replaced it w/ an AirDog system and have been driving it ever since w/ no trouble from the VP44.

If its still running then you might be lucky that the pump is not damaged, the big mistake dodge made was to not put a shut off safety if the lift pump should fail, diesel pumps run at huge pressure so heat and friction is helped by pumping fuel to the pump so it doesnt have to suck fuel from the tank, whats not used is curculated thru pump and back to the tank. So the fuel does lube and cool the pump, also cools the curcuit board mounted inside pump that when overheated will fry the transistors inside, there are some youtube videos of people fixing them. Could you have a bad relay if there is one?

It can happen on the 12 valve Cummins too. Difference is they run a mechanical lift pump that's much less prone to failure than the electric ones. However same thing happens, a guy replaces the lift pump after the engine starts acting up. It may run fine for a while but sooner or later (usually sooner) the injection pump goes. Those injection pumps are designed with the expectation that they will be supplied with pressurized fuel. Start making them suck fuel from the tank and they die real quick.