Stock fuel pump
Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
Stock fuel pump
question for you all about the stock fuel pump. my 77 has a relatively strong 355, say 400 HP. the guy that built it for whatever reason put an edelbrock victor race fuel pump on it and a bypass. plumbed out of the pump, into the bypass, 1 outlet goes to the carb and the bypass fuel goes to the stock return line. to say i hate this arrangement is an understatement, i cannot get the fuel pressure to dial in even remotely right. now, what is the capacity of the stock 3 port fuel pump? will it feed 6-7 psi, no regulator and run a say 400 hp engine at 6500 RPM?
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
Actually the big block and small block pumps are the same physically. You can get different pressures and volumes, but they'll bolt up and run fine. What makes you think you've got a fuel pressure issue?
Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
the car has a fuel pressure guage going into the carb that swings wildly between 2 and 12 psi. I swapped the guage and get the same thing. At rpm I see 9 to 11 psi. I have no fuel running out anywhere but at 11 psi there's no way the needles and seats are working like they should...
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
You're right, the needle and seat won't work right (for long anyway) at those pressures. Sounds like a regulator issue more than anything. For what it's worth, I went with a straight pump (no bypass) regulator and guage. I'm running 4.5psi with no issues.
Drifting
Joined: Jul 2009
Posts: 1,532
Likes: 14
From: Dallas-Fort Worth TX
Do you have a fuel filter? Might want to check that. damoroso is correct, you might need a regulator. I have a Holley Pump and regulator. I have it set at 6 psi according to my gauge. You want between 4-7 psi depending on your set up. 7 is really on the high side. Do you have any gas squirting out of the vent tubes on the carb?
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Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
Fuel filter is good. I have a bypass as opposed to a dead head regulator. No fuel flowing out the vents. What size lines are your running pump to regulator and then back to the return? Does your fuel pressure guage swing all over or is it pretty steady?
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
1. The Edelbrock Race Fuel Pump requires a regulator - are you using one?
2. Unless you are using a liquid-damped fuel pressure gauge through a restrictor, you will see needle noise reacting to pressure pulses at the needles resonant frequency - in other words, don't worry about the peak readings.
3. Bypass return fuel: It's a good idea - in fact I added a bypass (through a .058" restrictor hole) to my Edelbrock Performer RPM Street Fuel Pump (Pn 1721) on my '78. The pump doesn't require a regulator and has three sets of fuel valves internally to provide good flow - much better than the one set in the stock pump.
If you're concerned about the bypass, a stock pump has an internal metering orifice of .058" diameter which lets a small amount of fuel return to the tank to avoid shutdown fuel expansion issues, and it also helps keep fuel cooler when running by keeping fuel in the line to the pump in constant circulation.
Unless you're capable of running faster than 12.0 in the 1/4, the stock pump with a return bypass will work fine.
2. Unless you are using a liquid-damped fuel pressure gauge through a restrictor, you will see needle noise reacting to pressure pulses at the needles resonant frequency - in other words, don't worry about the peak readings.
3. Bypass return fuel: It's a good idea - in fact I added a bypass (through a .058" restrictor hole) to my Edelbrock Performer RPM Street Fuel Pump (Pn 1721) on my '78. The pump doesn't require a regulator and has three sets of fuel valves internally to provide good flow - much better than the one set in the stock pump.
If you're concerned about the bypass, a stock pump has an internal metering orifice of .058" diameter which lets a small amount of fuel return to the tank to avoid shutdown fuel expansion issues, and it also helps keep fuel cooler when running by keeping fuel in the line to the pump in constant circulation.
Unless you're capable of running faster than 12.0 in the 1/4, the stock pump with a return bypass will work fine.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
1. The Edelbrock Race Fuel Pump requires a regulator - are you using one?
2. Unless you are using a liquid-damped fuel pressure gauge through a restrictor, you will see needle noise reacting to pressure pulses at the needles resonant frequency - in other words, don't worry about the peak readings.
3. Bypass return fuel: It's a good idea - in fact I added a bypass (through a .058" restrictor hole) to my Edelbrock Performer RPM Street Fuel Pump (Pn 1721) on my '78. The pump doesn't require a regulator and has three sets of fuel valves internally to provide good flow - much better than the one set in the stock pump.
If you're concerned about the bypass, a stock pump has an internal metering orifice of .058" diameter which lets a small amount of fuel return to the tank to avoid shutdown fuel expansion issues, and it also helps keep fuel cooler when running by keeping fuel in the line to the pump in constant circulation.
Unless you're capable of running faster than 12.0 in the 1/4, the stock pump with a return bypass will work fine.
2. Unless you are using a liquid-damped fuel pressure gauge through a restrictor, you will see needle noise reacting to pressure pulses at the needles resonant frequency - in other words, don't worry about the peak readings.
3. Bypass return fuel: It's a good idea - in fact I added a bypass (through a .058" restrictor hole) to my Edelbrock Performer RPM Street Fuel Pump (Pn 1721) on my '78. The pump doesn't require a regulator and has three sets of fuel valves internally to provide good flow - much better than the one set in the stock pump.
If you're concerned about the bypass, a stock pump has an internal metering orifice of .058" diameter which lets a small amount of fuel return to the tank to avoid shutdown fuel expansion issues, and it also helps keep fuel cooler when running by keeping fuel in the line to the pump in constant circulation.
Unless you're capable of running faster than 12.0 in the 1/4, the stock pump with a return bypass will work fine.
Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
i'm running a dry guage. the bypass is a barry grant, has an inlet from the pump, outlet to the carb and a return port for excess, this goes to the stock return line. i just can't get the pressure down where it's supposed to be. it's all over the place and very frustrating....
Drifting
Joined: Jul 2009
Posts: 1,532
Likes: 14
From: Dallas-Fort Worth TX
I am not using my return line. But I plan to, just have not checked that off the list.
I am running 8AN line from the pump to reg to the carb. My gauge stays steady at 5.9-6.0. After I shut the engine down its still shows pressure until a few hours later it bleeds off.
It is not a liquid filled gauge as damoroso, describes. How does your car run?
Maybe try a new pump from the auto part store.
I am running 8AN line from the pump to reg to the carb. My gauge stays steady at 5.9-6.0. After I shut the engine down its still shows pressure until a few hours later it bleeds off.
It is not a liquid filled gauge as damoroso, describes. How does your car run?
Maybe try a new pump from the auto part store.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
i'm running a dry guage. the bypass is a barry grant, has an inlet from the pump, outlet to the carb and a return port for excess, this goes to the stock return line. i just can't get the pressure down where it's supposed to be. it's all over the place and very frustrating....
http://www.summitracing.com/parts/EDL-1712/
http://www.summitracing.com/parts/HLY-12-803/
Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
Does it matter if the diaphragm bypass, which I have, is mounted before or after the carb? Mine is currently before the carb but all the diagrams I found show the bypass after the carb. Could this be the cause of my problem?
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
I'm not sure at all, sorry. Like I said, give the Holley tech line a call. I'd bet within 10 minutes, you'd have the answer. Now I'm curious too!!
Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
Well, I emailed Barry Grant tech Monday. Told the exactly what I had, edelbrock victor pump, BG bypass, holley carb. Here it is Thursday and I have response zero. Maybe because I'm not running all Barry Grant they don't respond. Check with Holley next....
Racer
Joined: Aug 2007
Posts: 267
Likes: 0
From: Springdale Arkansas
stock pump won't keep up
If you run the car hard the stock pump will not keep up
The Edelbrock units if I am not mistaken have an internal bypass spring that you can change based on needs one for alcohol and the other for gas the differnet spring rated come in the rebuild kits you need 5-7 psi at all times stock pumps wont flow enough volume
The Edelbrock units if I am not mistaken have an internal bypass spring that you can change based on needs one for alcohol and the other for gas the differnet spring rated come in the rebuild kits you need 5-7 psi at all times stock pumps wont flow enough volume
Thread Starter
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
If you run the car hard the stock pump will not keep up
The Edelbrock units if I am not mistaken have an internal bypass spring that you can change based on needs one for alcohol and the other for gas the differnet spring rated come in the rebuild kits you need 5-7 psi at all times stock pumps wont flow enough volume
The Edelbrock units if I am not mistaken have an internal bypass spring that you can change based on needs one for alcohol and the other for gas the differnet spring rated come in the rebuild kits you need 5-7 psi at all times stock pumps wont flow enough volume