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Fuel psi from 20 to 13 psi???

FiveNine
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FiveNine

FiveNine

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That does seem like quite a drop. Could be clogged inlet or filters? Has it always done this or just recently started? Even my smaller 100 doesnt drop anywhere near that much at wot.

The AD system is 3 months old, how could anything be clogged? I just got the gauge hooked up yesterday, so i don't know how long this has been going on.
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FiveNine

FiveNine

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Clogged tank vent? Check after a run by slowly unscrewing the fuel cap. If you hear a hissing sound the vent is clogged. Happened to one of my trucks.

Hmmm I have noticed a hissing sound at the pump when taking the cap off. Can you explain why that will cause what o am seeing?
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JAG1

JAG1

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Hmmm I have noticed a hissing sound at the pump when taking the cap off. Can you explain why that will cause what o am seeing?

Lift pump will have to work much harder and loose pressure when the fuel tank can't breath. As you use up fuel air needs to displace the spent fuel. The OEM vent goes bad sometimes. I think I heard it's got a check ball that acts up sometimes. The check ball is in case of a roll over so the fuel can't leak out the vent. I put on my own vent to the left of the fuel cap.
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FiveNine

FiveNine

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Lift pump will have to work much harder and loose pressure when the fuel tank can't breath. As you use up fuel air needs to displace the spent fuel. The OEM vent goes bad sometimes. I think I heard it's got a check ball that acts up sometimes. The check ball is in case of a roll over so the fuel can't leak out the vent. I put on my own vent to the left of the fuel cap.

Makes since to me, So I should be able to leave the cap loose or off and take it for a test drive and that should tell me instantly if that was my issue.
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JAG1

JAG1

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Are you using the factory fuel filter as well because of the fuel heater? I have had dirt settle at the bottom of the cannister and then play havoc with my pressure as well. Isn't there a screen on the inlet side of the AD? Could possibly be clogged a little.

Yeah that too..... it's important to have a filter in front of the L/P. :thumbup2:
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FiveNine

FiveNine

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Are you using the factory fuel filter as well because of the fuel heater? I have had dirt settle at the bottom of the cannister and then play havoc with my pressure as well. Isn't there a screen on the inlet side of the AD? Could possibly be clogged a little.

No, the canister is long gone. where is the screen at?

Yeah that too..... it's important to have a filter in front of the L/P. :thumbup2:

No filter infront of my AD. The filter is built into the base.
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Mopar1973Man

Mopar1973Man

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There is a restriction some where for sure. Old School AirDog 150.. Center gauge. As you see it get down to 15 maybe a bit lower but not much. 2-3 PSI fall is typically for mine. Now I'm set for 19 @ Idle and 17 @ WOT. Now on the return trip I suck air bubble pressure will fall out.

http://www.youtube.com/watch?v=grl72Up-8T0

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FiveNine

FiveNine

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There is a restriction some where for sure. Old School AirDog 150.. Center gauge. As you see it get down to 15 maybe a bit lower but not much. 2-3 PSI fall is typically for mine. Now I'm set for 19 @ Idle and 17 @ WOT. Now on the return trip I suck air bubble pressure will fall out.

http-~~-//www.youtube.com/watch?v=grl72Up-8T0

Thanks Mopar! I did watch your video, and thats kinda why I am here. I figured something was wrong... I am running the Isspro gauge you linked in the post with this video. I bought th napa valve pn 6820, and also the air line you used. I would assume that there would be something in the tank, maybe the pickup tube? I helped a buddy install a 150 a wile back and his had a draw straw. Mine modified the sump. There was 2 screens, an inner and outer. the inner screen was removed so the new draw tube could pretty much sit right next to the outer screen. there is little bracket it fit into that spaced it from the screen if I remember right....
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FiveNine

FiveNine

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Air Dog with quick connects are prone to suction air leaks. :rolleyes: Change you plumbing back to old school JIC and Pushloc's and most of the problems go away.

:doh: anyway to verify that is the issue? If that is an issue, I can just change out the fittings coming from the tank to the LP correct? It wouldnt suck air being pos pressure from the LP to the IP would it?
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FiveNine

FiveNine

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Lift pump will have to work much harder and loose pressure when the fuel tank can't breath. As you use up fuel air needs to displace the spent fuel. The OEM vent goes bad sometimes. I think I heard it's got a check ball that acts up sometimes. The check ball is in case of a roll over so the fuel can't leak out the vent. I put on my own vent to the left of the fuel cap.

Just for the sake of trying, I took the fuel cap off and drove up the road, same results.
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JAG1

JAG1

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Eric at Vulcan Performance sold me the fittings to get rid of the quick connects. He was not surprised I wanted them gone. They just don't allow you to put the stock pump back on if your airdog raptor ever goes south. Eric did say he's told A/D they need to get rid of the quick connects cause they do leak air in.

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FiveNine

FiveNine

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Eric at Vulcan Performance sold me the fittings to get rid of the quick connects. He was not surprised I wanted them gone. They just don't allow you to put the stock pump back on if your airdog raptor ever goes south. Eric did say he's told A/D they need to get rid of the quick connects cause they do leak air in.

If you dont mind me asking, what did it cost to change the fittings? Kinda crappy I have to spend money on this... :spend:
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