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Lift pump/Fuel filter noise

6K views 12 replies 5 participants last post by  LB7diehard 
#1 ·
I have a simple PPE pump and a cat filter system. Any time I shut the truck off it still makes a noise like it's pumping or priming or something for 20-30 sec after. The noise appears to be around the fuel filter area(cat filter). Is this normal? First Duramax owner here lol. If no one knows what I mean I can record it.
 
#2 ·
Just a guess, but the LP relay could be wired into a circuit that stays hot for some period of time after the truck is shut off. Maybe the interior light ckt or something. Look in the fuse box for the "piggyback" fuse tap that powers the circuit. IIRC, I used the fuse labeled "ignition" or something like that, but it's been about 3 years so I don't remember for sure.....
 
#3 ·
I agree its more like where you tapped into for power, you want power from ignition on & off only instantly when the key is on or off.

A little help knowing what year your truck is for someone to direct you to which fuse location might be better.
A signature would be very helpful when asking for help.
 
#5 ·
There it is LOL :thumb
 
#7 · (Edited)


Try this one, one row closer to the firewall. IT turns on/off with the ignition.
 
#8 ·
Ally cat and Jg is right. I just installed my fass titanium. It's gotta be hooked to the ignition "E" fuse on mine. Whatever you do just take a simple test light or voltmeter and test which ones are hot with key on only and then shut the key off and check for power. If no power your good.
 
#9 · (Edited)


My fuse box is different than the op's, but I used #15 trans ignition.
Or
Like mentioned above find one that has power with key on, no power when key is off.

The one AirDog suggested was on the daytime driving lights circuit, which didn't work all the time.
 
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#10 ·
Someone correct me if I'm wrong but this why I went with fass instead of airdog. Trust me fass instruction wasn't much clearer or better. It's like they give you one instruction book for every model on the planet. I would do what I told you. Track down a hot lead on your own. A hot that's only hot when key is on and turns off as soon as key is off. And do not use daytime running fuse. It needs to be a key fuse only.
 
#11 ·
The position I posted above is only hot when the key is in the on position for LLYs and LBZs. Same spot recomended by AD in the instructions I recieved with all my pumps.


OP, you might want to check your fuses in the splitter too. Looks like you have a 10a fuse feeding the LP relay, pretty sure it calls for a 2a.
 
#12 ·
Back when I bought mine, my final choices was AirDog or FASS.
At that time FASS had absolutely no phone support, you had to drill the frame to mount the pump, cut and hose clamp the hoses.
I had to email my questions, about 3 weeks later when they finally got around to responding, by then I already had my AirDog installed.
This was about 3 1/2 years ago.

AirDog has phone support and has had a lifetime warranty for quite sometime.

And we're talking about fuse location not the operation and quality of the equipment.

AirDog uses hoses that quick connect to the factory connections, the only 90 degree is the hose that connects to the fill neck, and its a sweep 90 not a sharp 90 that's used with another popular brand.
 
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#13 ·
Ok ok D_R_C I knew I'd catch some heat on that one. Fass is way diff now. Full time tech support by phone and very knowledgeable. Everything is quick connect as well. Didn't have to cut anything. And no drilling the frame at all. Bracket mounts right to factory bed bolts. And these titaniums are quiet as a mouse. I mean I even tried to make a video of the sound of the pump in key on pos and you can't hear it. That's how quiet. Yes they've come a long way I guess. But back to the matter your right not a matter of quality or function. Both pumps mechanically are installed the same. I'm sure AD recommends using a key hot fuse as well. Hope you find the right key hot fuse bud.
 
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