12v fuel pump aftermarket or stock?? PSI questions..

wpeschel

wpeschel

Psyko
Joined
Aug 4, 2007
Messages
872
When is a aftermarket fuel pump needed? Is there a rule of thumb? Last I checked I had 60psi at idle, and 5psi at WOT. Since then my fuel guage started acting up, and is getting replaced by autometer. I have put on a new fuel pump.. What psi is needed at the pump?
 
wpeschel said:
When is a aftermarket fuel pump needed? Is there a rule of thumb? Last I checked I had 60psi at idle, and 5psi at WOT. Since then my fuel guage started acting up, and is getting replaced by autometer. I have put on a new fuel pump.. What psi is needed at the pump?
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30-40 psi to the pump is where you should be at. Get yourself an AirDog. Lifetime Warranty and its under a half a grand!:rockwoot:
 
Well, thats the nice thing about the A/D.... thats the pressure all the time...

Chase
 
How much is the airdog? Also how many different flowing models do they have? Where is the cheapes place to buy one??
 
I do, as well, but, I do not regret in the least my purchase... its quiet, flows great, filters are much easier to get at, and solved a few space issues in my truck.....

They come in 2 different models, though, I think a 3rd was just released...

100 and 150 gph...

Chase
 
Well I got my fuel pressure guage back in.. Idle is 50 psi, and I cant get it below 20psi on WOT runs... I'm going to stick with stock for not, but when I upgrade, the Airdog II looks like the ticket..
 
ILLINOISRAM said:
Wpeschel, how do you get 50 psi at idle? overflow valve mod?
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Yep just stretch the spring and viola..

After more testing I found I can pull the pressure down to 16psi or so.. I will upgrade in the future, but I just have a few other thing I need to get done..
 
Having run the stock setup for years with an aux setup I have always stood behind it but I got to see and hear an Airdog today for the first time and really like them, small and compact for a duel filter setup.

Jim
 
I think the stock setup works great up to roughly 500 horse considering my brother is right at 600 with his stock pump, but could he be over that with more fuel, we will find out someday.

Anyway, my thing that i dont agree with is psi means nothing compared to flow. Stretching the OFV is just a restriction like putting your thumb over the end of a garden hose, your flow will actually go down while the pressure comes up. AD150 with 1/2 inch line instead of the 3/8 will maintain 30-40 psi on a stock unmodified OFV.Put 3/8 line with the AD and the pressure will go up but a certain amont of flow would be sacraficed. For example, you could have 10 gph at 100 psi or you could have 100 gph at 10 psi. The 100 gph would be the best choice because it is more fuel to the pump and will be less agitated. And no, im not a salesman for AD. LOL Tim
 
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ILLINOISRAM said:
I think the stock setup works great up to roughly 500 horse considering my brother is right at 600 with his stock pump, but could he be over that with more fuel, we will find out someday.

Anyway, my thing that i dont agree with is psi means nothing compared to flow. Stretching the OFV is just a restriction like putting your thumb over the end of a garden hose, your flow will actually go down while the pressure comes up. AD150 with 1/2 inch line instead of the 3/8 will maintain 30-40 psi on a stock unmodified OFV.Put 3/8 line with the AD and the pressure will go up but a certain amont of flow would be sacraficed. For example, you could have 10 gph at 100 psi or you could have 100 gph at 10 psi. The 100 gph would be the best choice because it is more fuel to the pump and will be less agitated. And no, im not a salesman for AD. LOL Tim
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I completely understand the difference between GPM/GPH verses PSI, but when you increase PSI Flow increases as well.. I do however have to disagree that stretching the OFV spring decreaseds Flow.. That is not correct.. The OFV controls the rate of wich fuel leaves the pump back to the filter housing, inturn increasing psi in the pump.. I am interested to see what the max hp is with a stock LP..
 
I see what your saying about controling fuel leaving the pump. So at idle you will have a backup of fuel but you dont need it there.At WOT, do you truly have enough fuel to keep the rack fully fed, i dont think so because you still have the same pump moving the max amount of fuel it will move and that is why the psi is dropping because it cant keep up. So what did the OFV mod actaully help? If the psi wouldnt drop, then it would make sense to me but that aint the case here. Tim
 
I dont have any before OFV mod readings.. I see what your saying, the factory pump will only flow so much and that is it, no matter what psi it is set at.. I am wondering what the folks that making more than 600 on #2 are running?? I need twins on before I put a airdog on.. Maybe with the new airdog II pump coming out I can pick up a regular 150 used on the cheap..
 
I bought a AD150 for my build but i have not started it yet so i cant tell you how it works. My brother dynoed 591 on his stock lift pump that has been on the truck since he bought it 5 years ago so i would say the stock pump does a great job. We have never even put a psi gauge on it so we have no idea what it pulls down to, it could be 0 for all we know and maybe that is why he cant crack 600 on a dyno, who knows. This is all with the stock unmodified ofv too. I'm not trying to argue with you just having an adult discussion here. (Adult term used loosly in my case.LOL) Tim

By the way, i bought my AD through Showme-Smokers for 499$ shipped, set up the way i wanted it and it come with a extra fuel filter. I know it is still $499 bucks but that was complete and Matt was real nice getting me hooked up with one since i dont do paypal. I got the ad150, 40psi, drawstraw, and outside frame bracket and it does look good on the truck. Now if i just had a turbo.
 
Its all good.. This thread was started for me and others to learn.. I searched and didnt find any threads in regards to when a aftermarket pump become necessary.. I agree that the AD is a very nice unit.. Do you have to drop the tank to put the "Straw" in??? Why is a new one needed?? THanks Wesley
 
Yes, you have to drop the tank to install the drawstraw. The straw is 1/2 plastic pipe and 1/2 hose right to the AD unit. The stock pickup is only 3/8. I guess it wont allow full fuel to the pump for a ppump. Certain vp setups do use the stock pickup though. When does it become nessacerry, i dont know for sure. Me and my brother both have stock lift pumps on our 12vs and there are videos on youtube to show how they look hooked to sleds so i would say when you have the money and are ready to buy one. I used to have hybrid 35/40 over 3.0 hx60 twins with my bench built and flowed 500cc pump and i never noticed my stock lift pump not keeping up at 90 lbs boost. I did not have a fp gauge so i cant give numbers either. Tim
 
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