Fuel pump

[msggunny]

Amending to add that Weber's site specifically recommends avoiding the Facet pump. They describe it as "terrible".

The want to see me go with a Carter 4070.

Kind regards, Josh

I am prety sure that i am running the same pump with my 32/36 set up, its the one that the Webber people reccomended. The shop that instaled it made a bracket to block off the man pump on the engine block and they mounted the elect pump on it.

Works quite well, i have a cut off switch for security and when i want the igniton on but dont want to run the pump. I am going to look into the emergency cut off switch as mentioned above in case of an accident.

[scott]

gunny

i've a 32/36 and looking to upgrade from cheap electric to a carter electric. do you know the differences between the 4070 and the 4594? also going to put in a fuel return. do you vent back to your tank?

[alaskajosh]

I am prety sure that i am running the same pump with my 32/36 set up, its the one that the Webber people reccomended. The shop that instaled it made a bracket to block off the man pump on the engine block and they mounted the elect pump on it.

Works quite well, i have a cut off switch for security and when i want the igniton on but dont want to run the pump. I am going to look into the emergency cut off switch as mentioned above in case of an accident.

Someone told me that EFP's prefer to "push" rather than "pull" but apparently yours is doing a fine job of pulling.

I was planning to run mine in addition to the mechanical pump just as back up in case of mechanical failure or vapor lock. It would be on a switch and probably spend most of the time turned off. I hope there's no problem pulling fuel through a shut off EFP or pushing fuel through a dead MFP..??

I'm using a relay to turn it on with the ignition/coil so as not to have another load running through the key switch.

Check out a Hobbs switch for low pressure cut-off. NAPA #701-1575 is N.O. and closes at 4psi. Just "T" off alongside your oil pressure idiot light sender. $31 in Alaskan dollars.

What's the purpose of the fuel return?

Still have an air filter box you'd be willing to let go, gunny?

Kind regards, Josh

[scott]

i believe allowing fuel to return (recycle) will keep fuel line pressure from exceeding the efp settings, ie: efp set a 7 psi stops when back pressure hits 7 psi, heat arround fuel line continues to expand fuel, pressure goes up and vapor lock can occur. recycling the excess fuel keeps pressure at the pump's setting and allows fuel to cool when it returns to the tank. from what i've read the carter 4070 runs between 4-6 psi the carter 4594 6-8 psi. i'm running w/a weber 32/36 dgv and they like 4 psi but their needle valve can handle 15 psi so no regulator is needed.

am i right/wrong in my understanding? any weber experts out there? and anyone out there runing in the desert heat having/had heat related fuel delivery issues that a carter electric and return line has fixed?

[gudjeon]

The purpose of the fuel return is to keep a constant supply at the ready for the demand of the carb. Of course, it does not need the full volume of the pump's output all the time. The electric pump stays cooler with constant flow. There is no pressure left on the needle and seat once it is shut off. Also, the small return line outlet of the bypass filter has a small orifice so that the pump can build up some pressure, but not too much as be be easier on the float valve ass'y. The specs for the original mechanical pump call for lower pressures than most carb'd electric pumps, so I used it to err on the cautious side of things.

The return line can be seen on my second pic on the first page of the thread. It is very low tech. I made a mounting flange, drilled three holes, bent brake tubing, and soldered it to the flange. The tube goes most of the way to the bottom of the tank.

The return system is a bit like the diaphragm carb system used on small engines and old snomobiles. It supplies a constant volume of fuel and the carb sips off what it needs. The excess that it doesn't use goes back to the tank.

This is my take on it and take from it what you will. I have had too many frustrations with mechanical pumps to go back. Electric ones have been used on cars now for many years and still work going to the scrapheap pile after several hundred thousand miles. Besides, I can go to any local autoparts place/junkyard and get another.

[SafeAirOne]

I hope there's no problem pulling fuel through a shut off EFP or pushing fuel through a dead MFP..??

I'm using a relay to turn it on with the ignition/coil so as not to have another load running through the key switch.

My former 6-cylinder 109 has the factory-installed electric fuel pump (now disconnected) still plumbed into the fuel delivery system. I've been running it with the mechanical fuel pump sucking fuel through the unused electric pump for years with no problems.

The electric pump (was) wired off the white (+) primary coil circuit sans relay.