[rocky]

My question is should I change the #10 line from my cell to a #12. Current setup is #10 to Barry grant 5000 filter to a Magna Fuel 500 pump #10 from pump to a Magna fuel regulator from regulator #8 to Holley 1050 dominator. Car is a 79 firebird all steel 455 12.1 with #62 d port head a 630 lift roller victor intake 3800 8in stall 400 turbo and 4.10 gears. All stock suspension except for comp engineering traction bars and 10.5 30 hoosiers raidial slicks. the car best is 10.47 @ 129mph with a 1.47 sixty foot. Reason why I ask car hooks good then kind of gets lazy then once in second runs like crazy. I am shifting car around 6200 and thur traps around 6700

[Craig Hendrickson]

Any mechanical fuel pressure gauge or instrumentation for same? Also, what trap MPH?

[rocky]

I dont have any fuel pressure gauge in the car. I do have one connected to the regulator and at idle is set at 7.5 psi. If i rev the engine and watch gauge at regulator stays right at 7.5. the car goes thru trap at 129

[Tom Vaught]

Originally Posted by rocky

My question is should I change the #10 line from my cell to a #12. Current setup is #10 to Barry grant 5000 filter to a Magna Fuel 500 pump #10 from pump to a Magna fuel regulator from regulator #8 to Holley 1050 dominator. Car is a 79 firebird all steel 455 12.1 with #62 d port head a 630 lift roller victor intake 3800 8in stall 400 turbo and 4.10 gears. All stock suspension except for comp engineering traction bars and 10.5 30 hoosiers raidial slicks. the car best is 10.47 @ 129mph with a 1.47 sixty foot. Reason why I ask car hooks good then kind of gets lazy then once in second runs like crazy. I am shifting car around 6200 and thur traps around 6700

1) I personally have never seen a Magnafuel 500 pump run well as a "deadhead" system.

2) I would use a by-pass style regulator and run a -10 or 12 line as a return back to the tank. This will make the pump a lot happier. I also would block the return from the pump back to the tank. This way you get the full volume of the MF-500 to the carb.

3) I would make sure that I had dual 30 amp or 40 amp relays feeding the pump with a 10 gage wire from the battery to the relays and then from the relays to the pump +.

4) I would make sure that I had at least a 10 gage ground wire from the pump to the negative post of the battery (assuming that the battery is in the trunk).

More slow cars are due to issues on plumbing electric fuel pumps than you can imagine.

I would say that your issue is that the pump is having a hard time moving the fuel forward under 1st gear acceleration due to either wire size or the pump by-pass diverting fuel.

Tom Vaught

[rocky]

Tom I guess I have left a few thing out

1.I do have a #8 line by pass running out of the pump to the cell as they recommended

2. I have a painless wiring 30 amp relay mounted next to the pump

3.I have a 12 gauge wire grounding pump to the frame

[Tom Vaught]

I would get a second 30 amp relay and step up to #10 gage wire everywhere.

We had a 600 HP Mustang (supercharged car) that would not run the number on the track. They messed with it for a month. Finally came to me and said you have 2 days to fix it.

I changed the wiring and the relays and the engine easily made the numbers that they were after.

Based on your last post can you set the fuel pressure lower than 7.5 psi with your regulator? If not you need a larger return.

Tom Vaught

ps What regulator? PN #?

[rocky]

Again I am not giving you the entire story

I do have dual 30 amp relays. I can set the pressure lower than 7 I have had it down to 6.5 and up to 8

regulator # is 9633

I had a Holley big regulator on there when I switch to this pump and i could adjust the pressure just buried the gauge

[GTOGEORGE]

Do you run an alternator?


GTO George

[rocky]

yes i run an alternator

[Jagtec1]

My $.02 is that you do not need a larger line. Here is some good info:

http://www.centuryperformance.com/fu...e-spg-140.html

[Probird]

Originally Posted by Jagtec1

My $.02 is that you do not need a larger line. Here is some good info:

http://www.centuryperformance.com/fu...e-spg-140.html

I agree...#10 is plenty of line size.

[rocky]

so are you saying nothing is wrong

[Tom Vaught]

Boys are you saying feed line or return line

This statement supports what I am saying about the return side:

"The return line must have limited or NO pressure in it. In most cases, the minimum return line size will match that of the supply line, but a larger return line is sometimes preferred."

The man has a -10 feed line. He has a -8 return. Opposite from the above recommendations.

Explain please

Tom Vaught

[GTOGEORGE]

Get rid of the return line from the pump (block it off) and run a return line from your regulator (no.10). What about jet extensions in the rear?


GTO George

[Jagtec1]

He has a bypass, not a return. I say run a true return, and yes....you do need to check what the pressure on that side is. Should be no more than 2# or so when running full bore, IIRC. FWIW, I ran a -8AN feed and a -10AN return from the regulator, two -6 feeds to the carb.

[Probird]

Originally Posted by Tom Vaught

Boys are you saying feed line or return line

This statement supports what I am saying about the return side:

"The return line must have limited or NO pressure in it. In most cases, the minimum return line size will match that of the supply line, but a larger return line is sometimes preferred."

The man has a -10 feed line. He has a -8 return. Opposite from the above recommendations.

Explain please

Tom Vaught

Tom- The way I understand it is he was asking about inceasing the size of the feed line to #12. He doesn't have a return line. He's using a bypass at the pump. I think the #10 feed line is plenty. I agree with what you are saying though if he was running a bypass type system.

Have you tried running it without a filter element installed? Maybe it is the restriction. Are you using any sharp 90's?
I think the way you are currently running it should work just fine. I'm running an almost identical system. #10 to A2000 pump with a bypass to fuel cell, #10 to big Holley regulator deadheaded and #6 lines to carb. This is running alky and it works fine for my car at 140 i the 1/4. I did have a similar problem and it turned out to be low fuel pressure. The regulator backed down to 3 1/2 lbs. Jacked it back up to where it should be and it quit laying over on the gear change. Are you sure your guage is correct? What is the pressure from the pump to the regulator? I'm running 24lbs. to the front. Maybe crank up the pressure from the pump to the regulator.

[rocky]

Thanks for all your replies i and going to plumb in a #10 return and block off the by pass I will post the results

[gkinch]

Rocky,
My GTO was doing the same thing ! It was sloshing fuel out of the vent tubes when the car leaves hard ! I installed a rubber hose to connect the vent tubes with a couple of holes cut in it and this fixed the problem for me!

[punisher#1]

i run the same pump and filter combo as you do.
#12 to the filter, #10 to the magnafuel log with a large two port magnafuel regulator for the dominator and two holley 803's for the nitrous. #8 line from the bypass to the top of the fuel cell. two relays wired in parallel with #10 wire throughout.
this combo has been low 1.20 60fts and runs over 140 mph in the 1/8th on one kit. you do not need to re-engineer the bypass system.
you have a problem elsewhere. probably in the carb or the bypass adjustment itself. there is a 1/8 npt port on the pump housing used to monitor bypass pressure. for a hard leaving car with a rear mounted fuel system i would recommend 28-30 psi there with the engine running.
you may also try lowering the fuel pressure at the carb. with a large heavy needle and seat assy, the float can have a hard time regulating the fuel flow into the bowl when they suddenly drop. could actually be an over rich condition because of the fuel level being too HIGH in the bowl right after the launch.