[Fusion]

I have a 79 T/A with a 400 motor built to approx. 400 horse. I used to have a very small and very noisy electric fuel pump mounted in the rear of the car on the frame, just over the rear axle. Since the this pump was becoming very noisy and not delivering enough fuel at high rpms, i bought an 115 gph electric fuel pump from Summit (Summit's own brand of fuel pump), with regulator. I installed the pump in the exact same location as the old one, and mounted the regulator up front, with a fuel pressure fitting gauge right after the regulator. The pump is set to turn on when the key is turned forward, but not necessarily started. The first time I turned the key forward, I could hear the pump spring to life, but I was getting zero psi at the gauge at the front of the car. Sure enough, when I pulled the hose off the exit of the pump, no fuel was in the line, so after checking all the hose clamps for tightness, I dropped the gas tank, assuming that for some reason I was sucking air at the pickup. But when I dropped the tank, everything was sealed up tight. I pulled the hose off the carburator, and hooked it up to a manual siphon pump i had, and pumped gas manually up to the carburator, then hooked up the hoses again.
Now when I turned the key again, I had a nice 3 psi at the gauge. So I adjusted the psi via the regulator to about 6 psi, started the car, shut it off and on about 5 times and even waited 45 minutes and tried it again, and the pressure remained a constant 6 psi when the pump was on. So I thought I had success. But the next day when I turned the key over, the pressure shot up to about 8 psi, and was fluxuating between 3 and 8. I have no idea how this is possible since I am not leaking gas anywhere, I checked every single hose clamp. I drove it around the block a few times, and it seemed to be fine, but after about 30 minutes I could hear the fuel pump quiet down considerably (perhaps quit altogether), and the car died, and sure enough I was reading zero psi on the gauge. After 1 minute, I turned the key, and it was still reading zero psi, but for sure the pump was working as I could hear it. I let the car sit for about 20 minutes, and the pressure was about 3 psi, so I drove it home.
Does anyone know why in the hell the pressure would flux from zero to 3 to 8 when I guaranteed have NO gas leaks anywhere, the gas tank pickup is sealed, and all the hose clamps are tight??
How loud should the pump be when it is pumping fuel? I get a pretty consistent drone hhhhmmmmmmmmmmmmmmmm
It is fairly loud, but i have no experience with high-flow electric fuel pumps before, so I don't know if this is commonplace or not.

Also, my gas pickup is at the top of the tank, and the pump is mounted below the top of this pickup, but there is no way in hell i can mount the pump lower than the tank itself since it would hang down about 5 inches from the frame and scrape the ground.
Are there certain pumps that "push" better than "pull" and vice versa? maybe my last pump pulled and this new summit pump pushes, and maybe its not getting enough fuel from the tank? But I don't know how this would make the pressure flux so wildly on the gauge.

Could this be vapor lock?? The regulator and lines are mounted about 3 inches away from the upper radiator hose...but that still wouldnt explain why the pump seemed to be cutting out.

thanks everyone for your help, I really need to get this car rolling

Joe

[This message has been edited by Fusion (edited 06-10-2000).]

[Fusion]

I have a 79 T/A with a 400 motor built to approx. 400 horse. I used to have a very small and very noisy electric fuel pump mounted in the rear of the car on the frame, just over the rear axle. Since the this pump was becoming very noisy and not delivering enough fuel at high rpms, i bought an 115 gph electric fuel pump from Summit (Summit's own brand of fuel pump), with regulator. I installed the pump in the exact same location as the old one, and mounted the regulator up front, with a fuel pressure fitting gauge right after the regulator. The pump is set to turn on when the key is turned forward, but not necessarily started. The first time I turned the key forward, I could hear the pump spring to life, but I was getting zero psi at the gauge at the front of the car. Sure enough, when I pulled the hose off the exit of the pump, no fuel was in the line, so after checking all the hose clamps for tightness, I dropped the gas tank, assuming that for some reason I was sucking air at the pickup. But when I dropped the tank, everything was sealed up tight. I pulled the hose off the carburator, and hooked it up to a manual siphon pump i had, and pumped gas manually up to the carburator, then hooked up the hoses again.
Now when I turned the key again, I had a nice 3 psi at the gauge. So I adjusted the psi via the regulator to about 6 psi, started the car, shut it off and on about 5 times and even waited 45 minutes and tried it again, and the pressure remained a constant 6 psi when the pump was on. So I thought I had success. But the next day when I turned the key over, the pressure shot up to about 8 psi, and was fluxuating between 3 and 8. I have no idea how this is possible since I am not leaking gas anywhere, I checked every single hose clamp. I drove it around the block a few times, and it seemed to be fine, but after about 30 minutes I could hear the fuel pump quiet down considerably (perhaps quit altogether), and the car died, and sure enough I was reading zero psi on the gauge. After 1 minute, I turned the key, and it was still reading zero psi, but for sure the pump was working as I could hear it. I let the car sit for about 20 minutes, and the pressure was about 3 psi, so I drove it home.
Does anyone know why in the hell the pressure would flux from zero to 3 to 8 when I guaranteed have NO gas leaks anywhere, the gas tank pickup is sealed, and all the hose clamps are tight??
How loud should the pump be when it is pumping fuel? I get a pretty consistent drone hhhhmmmmmmmmmmmmmmmm
It is fairly loud, but i have no experience with high-flow electric fuel pumps before, so I don't know if this is commonplace or not.

Also, my gas pickup is at the top of the tank, and the pump is mounted below the top of this pickup, but there is no way in hell i can mount the pump lower than the tank itself since it would hang down about 5 inches from the frame and scrape the ground.
Are there certain pumps that "push" better than "pull" and vice versa? maybe my last pump pulled and this new summit pump pushes, and maybe its not getting enough fuel from the tank? But I don't know how this would make the pressure flux so wildly on the gauge.

Could this be vapor lock?? The regulator and lines are mounted about 3 inches away from the upper radiator hose...but that still wouldnt explain why the pump seemed to be cutting out.

thanks everyone for your help, I really need to get this car rolling

Joe

[This message has been edited by Fusion (edited 06-10-2000).]

[Bob Dillon]

In my experience, ALL electric pumps push better than they pull. It sounds from your description that the pump is defective. You've done everything right and it still runs inconsistently. Perhaps it's time for a warranty claim.

------------------
You really have to wonder
about the farmer who
discovered where milk comes
from.

[PONTIAC DUDE]

You need to see if you can shut the regulator off all together as it's a very poor design with the check ball in the regulator. I've had to se-seat the ball as it can leak pressure past the seat. causing eratic readings. also run your hot wire straight to a 12 volt source. no piggy backs. no relay's and use 12 guage wire. Are you on the primary or secondary side of the carb for pressure readings? Later. http://sites.netscape.net/pontiacdude428/homepage

[Fusion]

thanks for responding guys.

Dude: what do you mean when you say to shut off the regulator all together?? do you mean bypass it? I wanted to bypass the regulator just to see if that could be a problem, but I was afraid that the pump would be pushing way too much psi into the carb (3/8" line). Also, where would I hook up the direct hot wire to, so that the pump turned on when I turned the key forward to the ACC position?

I think the pump may be defective too


thanks

Fusion

[PONTIAC DUDE]

No, just back the screw all the way out and see if you have zero pressure as the diaphram is now unloaded. Take the line off the carb & see if fuel is leakin out. Of course this is with the engine NOT running. any fuel dripping is a sign of a faulty regulator. A must to check, especially running NOS. I also have resorted to fluid filled gauges as high line pressue to the regulator can make the gauge fluctuate rapidly back & forth making setting hard to set. later. however you souldn't have problems with the Holley type of pump. Something else to cosider is replacing the spring in the pump with a Moroso 19 psi unit. It chases the pressure better in high 2nd & the begining of the third gear range. Later. http://sites.netscape.net/pontiacdude428/homepage

[carbking]

All electric pumps with which we have dealings are 'pusher' pumps. We have have had less than satisfactory results with adjustable fuel regulators. All that we have tested tend to change pressure depending upon flow. Much prefer self-regulated fuel pumps. Unless this is a trailered race car, why 115 GPH? Check the design pressure (if you have installed a high volume fuel valve it will change) for the carburetor you are using. Try to find a name brand pump regulated to this pressure (generally available at your local parts store). As to the wiring of the pump, if this is a street driven vehicle, federal law mandates permanent wiring energized by some engine 'on' device, such as an oil pressure switch. We think it is an excellent idea for safety. You can legally install a push button 'override' to energize the pump before you turn on the key (saves on the starter). This will de-energize when you release the button, and the permanent wiring will keep the pump energized. Jon Hardgrove

[JSchmitz]

Sounds like the old Holley blue pump. I have seen several of those where the internal bypass piston hangs up. This would explain your problem. The internal leak makes it impossible to regulate.