Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
#1
Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
Hey guys,
I'm curious if I will be able to truly regulate the PSI of say a 255lph fuel pump meant for fuel injection down to the 6psi needed for my carbed motor. This won't hurt the in-tank pump will it?
I'm curious if I will be able to truly regulate the PSI of say a 255lph fuel pump meant for fuel injection down to the 6psi needed for my carbed motor. This won't hurt the in-tank pump will it?
Last edited by Ozz1967; 12-14-2010 at 10:33 PM. Reason: Spelling
#2
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Car: 1986 Iroc-z Camaro t-top
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
Mechanical pump is what I went with and it was the easiest in my opinion
#3
Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
Yes you will need to take your pump out and run either an electric pump mounted on the car somewhere or a mechanical pump. You will burn up your factory pump and it won't suck any fuel out if you switch to a different pump unless you take out your factory pump and replace it some 3/8 fuel line hose.
Mechanical pump is what I went with and it was the easiest in my opinion
Mechanical pump is what I went with and it was the easiest in my opinion
So I'm stuck with trying an in-tank fuel pump option unless there's another option out there I haven't tried yet.
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
You can regulate it down just fine.
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I disagree with that. I had a carb on my car at one point and had a holley 255 LPH in tank pump. Using a very high quality pressure reg (aeromotive) I could NOT get the pressure below 8-9 psi using the stock fuel lines. To go much lower I think I would have needed to run a larger return line. At one point, I basically had the regulator adjustment screw backed out to the point it almost fell out. I never saw under 9 psi.
#6
Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I disagree with that. I had a carb on my car at one point and had a holley 255 LPH in tank pump. Using a very high quality pressure reg (aeromotive) I could NOT get the pressure below 8-9 psi using the stock fuel lines. To go much lower I think I would have needed to run a larger return line. At one point, I basically had the regulator adjustment screw backed out to the point it almost fell out. I never saw under 9 psi.
5/16 like my carbed one?
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Car: 1984 Z28 Hardtop
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
Put it in perspective. The volume flowing through the return is the same, regardless of the pressure you set the regulator to. If it ran with FI, it will run at lower pressure with a carb.
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Car: 1984 Z28 Hardtop
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
Why are you going to have 8-9 PSI to the carb?
#10
Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I was basing that statement off the previous posters' experience of not being able to get the fuel pressure down below 8-9psi. I don't know yet how well my mallory regulator will work with the new in-tank pump. So I am worried I won't be able to get thepressure down to 6-7psi. I'll find out this weekend when I do the install I guess.
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I'm just giving some insight on my problem. On paper it seems like it should work but that was my true life experience. All set up's/ pressure regs aren't created equal and mine would not go below 9 psi with stock lines and a 255 pump. I heard from a few other guys that a larger return line may be neccesary
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Car: 82 Berlinetta/57 Bel Air
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Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
The key is keeping flow going through the pump. If you can't regulate the output down to 6 psi with a bypass regulator because of the return line size, put another dead-head reg between the bypass reg and the carb inlet, and set it to 6 psi.
#13
Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
Where do I check the pressure at then? At the dead head or at the return regulator? I did get a deadhead regulator with my most recent Holly blue pump purchase, came with the pump.
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At the carb inlet. I'd see if the return type reg controlled it first, then add the deadhead if necessary.
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Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I've used a stock pump and a walbro 340m pump which is 255lph or 67 gpm. Been working for years(8+). I've used the universal aeromotive bypass regulators( comes with an efi and a carb spring). Also used a mallory bypass regulator.
I always ran 6-8psi. Anything over 8 is pushing it. I've seen a lot of floats stuck open.
Also using stock fuel lines. 600hp carb setup.
I always ran 6-8psi. Anything over 8 is pushing it. I've seen a lot of floats stuck open.
Also using stock fuel lines. 600hp carb setup.
Last edited by AutoRoc; 12-17-2010 at 06:32 PM.
#17
Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I've used a stock pump and a walbro 340m pump which is 255lph or 67 gpm. Been working for years(8+). I've used the universal aeromotive bypass regulators( comes with an efi and a carbon spring). Also used a gallery bypass regulator.
I always ran 6-8psi. Anything over 8 is pushing it. I've seen a lot of floats stuck open.
Also using stock fuel lines. 600hp carb setup.
I always ran 6-8psi. Anything over 8 is pushing it. I've seen a lot of floats stuck open.
Also using stock fuel lines. 600hp carb setup.
#19
Re: Running 255lph fuel pump, can I regulate it down to 6psi? Hurt the pump?
I installed the second dead-head regulator immediately after the first, actually connected the two with a male-male 3/8NPT fitting. I've got the pressure gauge immediately after the second regulator followed by braided line to the carb. The pressure was nearly at 2psi and I couldn't really regulate it up unless I had the mallory turned almost all the way in (highest pressure setting). I tried adjusting using the dead head but aht didn't move anything. So, I just set the dead head roughly in the middle then used the mallory to set the pressure. Turned almost all the way in I got the pressure after the dead head to rise to 5.5psi and locked it in there. So far no evidence of bleed-through on my gaskets so I think I'm good there.
Now, if I can only figure out why my sending unit is reading passed full.... lol If it's not one thing it's another. Going to have to watch the odometer and get gas every 100 miles until I figure this out. lol
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