Fuel pump / regulator / Physics help
Thread Starter
Heel & Toe
Joined: Jul 2007
Posts: 19
Likes: 0
Fuel pump / regulator / Physics help
Hello,
I have a 68 Corvette with roughly a 590hp big block. I have used a fuel pump with regulator that according to my local speed shop is the same as Holley's "black" electric fuel pump. Unfortunately, I have gone through two of them due to leaking.
I plan to purchase the real Holley "black" pump and regulator. A Jegs sales representative told me that I need to run a by-pass line from the releif port of the regulator back to the tank. My tank does not have the releif port, so I was planning to drill into my tank and use a bulkhead fitting to get my releif plumbed to the tank.
I then had another idea, but now Physics becomes envolved. Could I run the releif line from the regulator to the line that is between my tank and electric fuel pump? If I just simply "tee" into this line, I would have the weight of the gas in the tank pushing against the releif pressure, which in turn would be feeding the pump, again. Can anyone weigh in on this idea? Would it work?
Thanks in advance
I have a 68 Corvette with roughly a 590hp big block. I have used a fuel pump with regulator that according to my local speed shop is the same as Holley's "black" electric fuel pump. Unfortunately, I have gone through two of them due to leaking.
I plan to purchase the real Holley "black" pump and regulator. A Jegs sales representative told me that I need to run a by-pass line from the releif port of the regulator back to the tank. My tank does not have the releif port, so I was planning to drill into my tank and use a bulkhead fitting to get my releif plumbed to the tank.
I then had another idea, but now Physics becomes envolved. Could I run the releif line from the regulator to the line that is between my tank and electric fuel pump? If I just simply "tee" into this line, I would have the weight of the gas in the tank pushing against the releif pressure, which in turn would be feeding the pump, again. Can anyone weigh in on this idea? Would it work?
Thanks in advance
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
The reason for the regulator return line is to put the fuel that's heated up by the pump back in the tank. It also insures cool fuel gets to the pump to cool it. This is generally a bigger problem with higher pressure efi systems.
You can T into the line before the pump and if you dont have vapor lock issues or overheat pump failures, you'll be fine.
You can T into the line before the pump and if you dont have vapor lock issues or overheat pump failures, you'll be fine.
Thread Starter
Heel & Toe
Joined: Jul 2007
Posts: 19
Likes: 0
Garys 68, thank you for the reply. The Jegs rep did mention that my pumps had been failing due to heating up, which was caused by the no releif from the regulator. I guess that it is trying to pump so many GPM at 14psi, and I am restricting it down to 6psi. I did not think about the fuel being hot, too. I see what you are saying about sending hot fuel back to the pump.
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
If you wee not returning fuel with a 14psi pump and a regulator, that will definitely kill a pump. Your other option is a pump made for a retunless system. I've had a lot of luck with the Mallory 110, no regulator/retun required. Easily supported a 550hp SC motor.
Garys 68, thank you for the reply. The Jegs rep did mention that my pumps had been failing due to heating up, which was caused by the no releif from the regulator. I guess that it is trying to pump so many GPM at 14psi, and I am restricting it down to 6psi. I did not think about the fuel being hot, too. I see what you are saying about sending hot fuel back to the pump.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Not trying to be a smartazz but the physics involved I can see is walking into Jegs and getting a Carter Billet aluminum super street
racing pump for about 100 bannas.
If you only need 6psi or so then why go electric when a mechanical pump will do. Back in the day every race car at the track had an electric pump but I have been seeing more mechanical pumps these days.
Mine is for small block M6900 and it flows 120 - 140 gph. My motor is 600HP more or less don't know yet but I have had it up to 6000RPM on the track and there was no problems with it.
racing pump for about 100 bannas.
If you only need 6psi or so then why go electric when a mechanical pump will do. Back in the day every race car at the track had an electric pump but I have been seeing more mechanical pumps these days.
Mine is for small block M6900 and it flows 120 - 140 gph. My motor is 600HP more or less don't know yet but I have had it up to 6000RPM on the track and there was no problems with it.
