Lift pump voltage

[Mschuman88]

hi all,

Hoping you can help me.

I have a 2002 2500 with a 5 speed. It’s all stock with the exception of an edge juice that was installed by the original owner...I keep it at stock settings. I also have a raptor 4g lift pump I put on in May of last year.

On my way home from work the other morning, my fuel pressure dropped to under 3 psi instantly. I pulled over and shut down the truck. I bumped the starter to see if the pump would run and it did. I restarted my truck and let it idle, and it held a steady 18 psi for a minute so I decided to take off.

Within 10 seconds the pressure dropped again. I pulled over and had it towed.

I called air dog and they said it sounds like my ecm is not properly keeping voltage, so i should wire my relay to a key on power source.

I found a fuse and used a tap kit today. As I was doing that, the radio went out and suddenly I got a check gauges light.

I was following the instructions. I hope I didn’t mess up the whole system.

Any suggestions on how to proceed? I was going to wire a switch from the cigarette lighter fuse to power the relay.

Any recommendations on a good mechanic for these trucks in Wisconsin?

Thanks,

Matt

 

[DavidC]

It could also be your in tank screen plugging up.Mine dropped to 3 , changed pump still 3. Blew 15 psi of air from the pump back to the tank. Viola, 15psi, drove about 50 feet and back to 3. Pulled the module and there was a vaseline like substance on the screen impeading fuel flow. You could rig a hose from your pump inlet to a 5 gallon jug and see if the problem persists.

 

[Mschuman88]

Ok, update.

Reading a diesel manor article on gauge installation, I tapped a black wire with brown trace and wired a grounded switch. I verified with my multimeter I had 12v going to the switch. I then Connected that switch to the air dog relay.

After I completed all my splicing and heat shrinking, I turned the switch on a voila, the lift pump kicked in and I had 18 psi of pressure.

I proceeded to start the engine and suddenly the lift pump turned off again. I verified that the pump is still in working order.

I now am not getting 12v through that tapped wire. All my splices look good. I’m thinking a fuse or relay died? Does anyone know what system this wire is a part of?

The wire mentioned is the same in this diesel manor post. Thanks in advance

http://www.dieselmanor.com/diy/CMS-G2gauges/CMS-gen2gaugeinstall.asp#

 

[Ozymandias]

Well, most Ignition (ACC/RUN) HOT wires switch OFF while cranking, so you probably got one of this.
If that is a problem to you, it isn't for the engine or the VP44, then you need to search for one of the few ACC/RUN/START wires to connect to.
Or you leave it like it is now, there will be no harm to the VP44 for that short time of cranking.

And as David said, check your Intank screen that this is clean, no kidding.

Oh, and why did you let tow the truck, this VP44 pumps can run for months without a lift pump - until they die. There sure is no problem to run them for a short time and light foot that way.

 

[petersonj]

sure is no problem to run them for a short time and light foot that way.

I totally agree.

- John

 

[Mschuman88]

ThAnks for the posts. I will check the screen when I drop the tank next.

Also, the switch is a lighted toggle. It was lit up with the key in the start position before I tried to start the truck. After the starter kicked in the light went out and I lost voltage to that line.

I’m wondering if I fried something...

Also, air dog customer support has been pretty non responsive. This is the third major issue I’ve had with my pump in less than a year.

 

[Chief USA]

Have you tried bypassing the relay for the pump? A bad relay may run for a short time and then fail also. Just another thing to consider.

 

[Ozymandias]

Also, the switch is a lighted toggle. It was lit up with the key in the start position before I tried to start the truck. After the starter kicked in the light went out and I lost voltage to that line.

And the light/voltage didn't came back when the engine started and you stopped cranking?
This line is now permanently down?

 

[Mschuman88]

And the light/voltage didn't came back when the engine started and you stopped cranking?
This line is now permanently down?

Yes, exactly. The engine will start and run, my edge will just go crazy and alarm for O psi.

I did let it run yesterday and confirmed my pump really isn’t turning on at all.

I also checked the voltage at the harness and it’s showing 0 with both the key on and running.

It feels like a fuse. I checked the fuses in the cab by drivers door and the engine bay but all looked intact.

Again, I appreciate the help in responding

 

[Mschuman88]

Have you tried bypassing the relay for the pump? A bad relay may run for a short time and then fail also. Just another thing to consider.

I have jumpered the power at the relay with a wire and the pump will turn on and deliver good fuel pressure.

I don’t know how I would do that permanently. I’m not the most electrically competent guy.

It might be time to through in the towel...

 

[Ozymandias]

Ok, so you did something dangerous, you connected to a cable that you didn't know what it is good for. Never do that, I know I'm late with this info...
One need to know that cable colors change from MY to MY, never trust on an information that isn't exactly for your MY.

For now, connect your pump relais wire to the cig lighter, that is (usually but check first) ACC and is 15Amp fused.
Then we need a wiring diagramm for your MY to figure out what that cable you plumbed in is good for, and repair it.

And then you need to install a testlight to the OEM connection of the fuel pump to check if this wire really shuts down after some run time, there is also the possibility that your Pump relay for some reason pulls to much amperage and the ECM shuts down the circuit for self protection.

Fighting the causes not the symptoms.

 

[Mschuman88]

Ok, so you did something dangerous, you connected to a cable that you didn't know what it is good for. Never do that, I know I'm late with this info...
One need to know that cable colors change from MY to MY, never trust on an information that isn't exactly for your MY.

For now, connect your pump relais wire to the cig lighter, that is (usually but check first) ACC and is 15Amp fused.
Then we need a wiring diagramm for your MY to figure out what that cable you plumbed in is good for, and repair it.

And then you need to install a testlight to the OEM connection of the fuel pump to check if this wire really shuts down after some run time, there is also the possibility that your Pump relay for some reason pulls to much amperage and the ECM shuts down the circuit for self protection.

Fighting the causes not the symptoms.

Good coaching... thinking I should have taken this to a professional.

I’m going to work on it some more this weekend with my uncle who is an electrician. I’ll give you his advice and go from there.

Thanks for the early AM response!

 

[Ozymandias]

No prob, until then you can do some work and print out a wiring diagramm for your truck.

https://www.google.com/search?q=wir...1&ved=0ahUKEwiPr-DykfffAhXr4IUKHU9qASUQvwUICg

Your uncle will need that.

 

[Chief USA]

Deleted

 

[Chief USA]

I have jumpered the power at the relay with a wire and the pump will turn on and deliver good fuel pressure.

I don’t know how I would do that permanently. I’m not the most electrically competent guy.

It might be time to through in the towel...

If you did in fact bypass the relay with the jumper wire and the pump ran continuously without interuption, it would seem to me that there is a good possibility the pump relay may be bad or malfunctioning. I think I would contact Air Dog and either get them to send you a new relay or find out the specifications of the relay and buy one locally. Swap in the new relay temporarily and test drive the truck. If the fuel pump is now operating properly, you have confirmed the problem. Now go back and properly and permanently install the new relay in place of the failed relay. In bypassing the questionable relay, all you have done is provide battery power directly to the pump for test purposes which is what the relay is supposed to do.

 

[JR]

I always carried a spare relay in my glove box when I had an Air Dog lift pump.

 

[DavidC]

Best to check to see if the relay is getting power to energize across the coil with a meter or test light,then check power to ground on the contacts. Did you check the fuses in the PDC under the hood as it sounds like you blew a fuse.

Dave

 

[Ozymandias]

It's a plain standard relay that is used for the Pump. The sort we all have flyin around in our workshops.

https://pureflowairdog.com/file/23-...-1998-5-2004-qc-install-manual-rev-8-2-16.pdf

 

[Mschuman88]

Hi all,

The first thing I did was replace the relay with another from the auto parts store in town. That’s when I still had the relay wired to the stock lift pump connector

Same thing...18 psi at idle, after driving dropped to 3.

I’ve got the diagram printed and ready. I appreciate the support.

Wish Air Dog had the same response time as you guys...

 

[Mschuman88]

Also, would bad grounds or weak batteries cause anything like this. I bought some new cables from Geno’s a while ago, just haven’t installed. Was planning on doing that, plus starter contacts, plus clean the grounds...when it’s warmer