fuel pressure dropping at WOT

dodge05cr

dodge05cr

Granny Shifter
Joined
Aug 28, 2009
Messages
130
hey guys Im running PPE dual cp3's. Cummins pump with arsonIII on the bottom and stock dmax on top. For a lift pump Im running an airdog 165. At idle my fuel pressure is 15psi and on WOT pulls its will drop to around 1-4psi but the rail pressure gauge is still holding 25k. I tested my Airdog and it all seems to be working correctly, along with 2 new filters. I was told to do dual airdogs along with a fuel distribution block. I don't know why Im having this problem tho, Im around 700-800 hp.
 
Did I talk to you at the roadway? I think maybe I did.

Did you try cranking up the 165?
 
Snedge said:
Did I talk to you at the roadway? I think maybe I did.

Did you try cranking up the 165?
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Yeah that was me haha! Well I was told that the dmax pump can only handle 15-16 psi max... so thats why its at 15 lol
 
Before I'd purchase another pump. I would try going to a larger diameter feed line to the CP3's. Could be the volume is all you need. Same pressure, just more available.
 
Are you running 1/2" line between the tank and pump? What are you using for a sump out of the tank?

I would start on the suction side of the pump.

What filters are on the AD?
 
Snedge said:
Before I'd purchase another pump. I would try going to a larger diameter feed line to the CP3's. Could be the volume is all you need. Same pressure, just more available.
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Could be possible.. From the Airdog to my bottom pump is 1/2 inch but the line going to my top cp3 is smaller. What about the return lines then, do I need to make them bigger as well, if so how big?
 
Put a Cummins fca in that dmax top pump and run all the pressure you want.
 
How old is that AirDog? A larger line to the top pump should help, i wouldn't, mess with the return lines, would be wasted energy imo.

That one pump should be able to keep up with what you have. You first may want to look into doing a junction Y block first. Run a single -8 line to the block then dual -8 or -6 lines to each pump. If you're still dropping then the AD isn't putting out what it should.
 
1lowdiesel said:
How old is that AirDog? A larger line to the top pump should help, i wouldn't, mess with the return lines, would be wasted energy imo.

That one pump should be able to keep up with what you have. You first may want to look into doing a junction Y block first. Run a single -8 line to the block then dual -8 or -6 lines to each pump. If you're still dropping then the AD isn't putting out what it should.
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The airdog is probably has 10-15,000 miles on it. It always worked fine with the single cp3 and I was running 22 psi at idle. Now I did the dual fuelers and with a dmax pump i was told to run it at like 12-15psi at idle. But I do have a cummins fca on the dmax pump and was just informed that with a cummins fca I can run more pressure at idle. So maybe I will try turning the pressure up and see how that works before I do another airdog. And for the lines, can i run a 1/2'' line from the airdog to the fuel block and then "2" 1/2'' lines to both cp3s. Plus turn the pressure up to like 18-20 and go from there.
 
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Yes that would work fine. Like Snedge said, sounds like it could just be a restriction in volume issue. You def don't need 2 pumps.
 
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