? Fuel pressure drop
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? Fuel pressure drop

  1. #1
    Senior Member cave's Avatar
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    Default ? Fuel pressure drop

    I picked up an Aeromotive 13204 bypass regulator. I'm having a provlem keeping the fuel pressure up. it will hold 8lbs when the pump is turn on. but as soon as the motor runs the pressure drops when the engine lopes. The fuel returns to block that I made . kindof like a Y block with the center of the Y being drilled out to route the fuel retuning from the regulator.Next I returned it to the fuel water separator filter. The return line is -8. The feed line is -10. I can't return directly to the tanks cause there glassed in and 45 gallons of AV gas is in em. any sugestions on how I can rout this to eep the pressure up. Oh. fuel pump. 1st one was a Holley blue just to test. Next is a Holly 12-150.
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    Resident Ford Nut Sleeper CP's Avatar
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    Quote Originally Posted by cave View Post
    . The return line is -8. The feed line is -10. .
    Make the return line a -4. Problem solved maybe even a -3
    Second thought -3 would be to small ( edit)

    You only need to bleed off enough pressure so the fuel pump is not stacking up the fuel and getting hot, you don't need to return 67% of the fuel you're pumping. The fluid will follow the path of least resistance so if the fuel can run through the regulator or go to the return line it will go to the return line.

    Sleeper CP
    Last edited by Sleeper CP; 02-03-2009 at 05:48 PM.

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    Senior Member H20MOFO's Avatar
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    Would 1/8"npt be too small?? In other words, could you do a return line to a an flare fitting with an npt port? Or would that be too small. (1/8npt)
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    This sounds like low voltage....does this at idle?
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    Senior Member cave's Avatar
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    Yes it does it at idle and when I got on it at the lake it dropped to around 3lb so I shut it down. I idled back to the no wake safe zone.

    I Told my Bro Marqo that its seams like the pump is just feeding from the return line. I'll have to see if Shop 4720 has any more -4 fittings and line -4 and give it a shot. If it don't work I an use it on the Hydraulic diverter

    Areomotive tech said It should be no smaller than -8 or the pressure will drop. It seams like it should be the other way around to me too. If I was to return to 1 tank that tank would over flow or not draw fuel till the other was empty. I can hear the fuel passing through the regulator via the bypass. Its sounds like a fast moving stream.Thanks Sleeper CP Err uh I mean Mr President
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    try pinching the hose down with some vice grips and see what happens before you throw any money at it

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    Senior Member cave's Avatar
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    Thats a good idea. Not to sure if I can pinch the stainless Braided line but maybe enough to restict it a bit.
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  10. #8
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    I have run in to this problem many times with the aeromotive pump. It is actually too much pump. I have designed a full loop bypass system for that pump that works, and holds steady pressure. The problem does lie here, You have to return back to the tank, not the fuel line. The tanks also need more venting than a cap type vent, and the pump and the regulator needs to return. I can help you with this problem. I have heard all of the oppinions, and solutions from even aeromotive, and they have been not very helpful. Basically, you copy the Product engineering system, full loop, and its a no brainer. Aeromotive, to me has a misleading product line, and will sell the average guy way too much pump, then you have to buy all these other items just to make it work, when most can use a 175per gallon or more and be just fine. Lets put it this way, we ran a holley black pump on a record holding comp dragster, with a 1250 h.p prostock motor, ownered by John Chamberlin. The real problem with boat guys is they draw off of two tanks, and that is wrong, even if it works, its wrong.

  11. #9
    gn7
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    I agree that the return line doesn't need to be any bigger than necessary, but the restriction is in the bypass. It shouldn't flow any more fuel to the return than needed to maintain pressure. The return flow on a MFI isn't determined by the line size, it's set by the pill, and or spring. I think he has a voltage problem. What is the TOTAL wire length of the circuit, and wire size. Please tell me that did not run this thru the key!



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    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    Quote Originally Posted by J Shelfo View Post
    The real problem with boat guys is they draw off of two tanks, and that is wrong, even if it works, its wrong.

    Yup! Thats why I run a valve on both of my tanks. I run 1 tank at a time
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    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    Quote Originally Posted by gn7 View Post
    I Please tell me that did not run this thru the key!

    Hopefully there is a bosch 5 pin relay,30 amp fuse and a wire that runs to the key
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    They bout shit themselves when yelled in Messican, "No brakes no brakes."
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    Like Jshelfo said, I think the problem is, the return line goes back to the suction/ feed line. I have seen sooo many people run into problems trying to make this work.


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    So you are running a holley pump with a aero regulator. Return line does not determine pressure like GN stated thats the purpose of the regulator. I would check for voltage fluctuation at the pump and possibly the loop you have for the return. Also double check that you have the regulator plumbed correctly. What size feed line are you using? Lastly set your fuel pressure with the engine running.

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    Quote Originally Posted by J Shelfo View Post
    I have run in to this problem many times with the aeromotive pump.
    Aeromotive, to me has a misleading product line, and will sell the average guy way too much pump, .


    Quote Originally Posted by cave View Post
    I picked up an Aeromotive 13204 bypass regulator.

    Oh. fuel pump. 1st one was a Holley blue just to test. Next is a Holly 12-150.
    FYI,

    Cave that Holley blue has a somewhat small intake port if memory serves me correctly, unless you did a lot of clean up work on it. That -8 return line is just way to big for a pump that puts out as little fuel pr/hr as that Holley blue does. Do try it with the Holley black but you do need to replace that return line with a -4( I guess I should ask as GN 7 stated, Is the by-pass line before or after the presssure diafram ?) If it's after the diafram retrun line size won't matter). As other's have stated you do need a relay in the system.


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    Last edited by Sleeper CP; 02-04-2009 at 12:06 PM.

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