What's the pro's/cons of mech or electrical??

[The_Dealer]

im wondering what the pro's and cons are of mechanical vs electrical fuel pumps. when i put my new holley on i used a clear fuel filter from summit and i noticed that when my rig is parked for more then an hour all the fuel runs out back into the tank i presume. also when i crank it up for the first crank of the day(esp when its cold out) it takes forever for it to run right. when i put it in drive it shuts off and doesnt want to run, but if i get it in gear and give it gas it feels like its gonna stall, backfires out of the carb, but if i pump the gas while im taking off it goes, then about a mile or so down the road it runs fine. doesnt matter if i use the choke or not, or if i leave it running to warm up temp. also wont stay idle very well till its fully warm. ive driven carb'd vehicles before but always with electric fuel pumps, and usually i rev'd them a few times and they were good. is there another problem and not the fuel pump? rig is the one in sig

 

[martin]

If one of the valves in the mechanical pump is not sealing completely it will do that. Any kind of leak, no matter haw small will also cause the same thing.

 

[The_Dealer]

i dont think that i have any external leaks, it worked good before the holley, although it just gradually started getting worse and worse, whats the best way to check for fuel leaks? ive inspected everything with engine running and have no leaks that i could see. although fuel on a hot engine will evaporate in no time

 

[doorgunner]

I have the same problem.....but not as bad. I have a Holley 650 connected to a inline fuel pressure gauge at the carb fuel inlet. That's connected to a fuel return regulator which connects to the inline hi-pressure filter which connects to the Ford O.E.M in-tank electric fuel pump. Overnight, the fuel will drain back into the tank leaving just enuff fuel in the carb to start the v-8....then the engine sputters & dies.

So.......as soon as I get in the truck, I turn the key on....I hear the fuel pump running & pressurizing the lines....I buckel up/adjust the radio/take a sipof coffee/turn on the GPS......press the accelerator 1/2 way down & it cranks up & idles with no problems (the fuel pump just needs 15-20 seconds to build up pressure to the carb & force any trapped air back into the tank thru the return line after it's been sitting up for a while) .

As for a mechanical pump, Dealer has a good idea about a reverse-flow valve being stuck open inside the fuel pump( or a pin-hole in the rubber diaphram in the mech. fuel pump allowing the fuel to return back to the tank causing the whole fuel line to be filled with air)

 

[gwaii]

something to check as well is smell your oil.

sometimes when a diaphragm on a mechanical pump gets a hole in it fuel can leak into the crankcase,thinning down the oil.if your oil smells like gas,change the pump pronto.

change the oil and filter too.

 

[The_Dealer]

oil is good, doesnt smell like gas

 

[gwaii]

good.more than one engine has been ruined from that.

 

[Robert_1967]

Also one other thing, on a electric fuel pump, you need a return line, and fuel pressure regulator, since a carburetor only needs 6 to 8 pounds of pressure.

you might also want to check the carburetor, once you get it running and it still want to backfire through the intake, then the carburetor is out of whack, I friend of mine has a Dodge van with a 360 in it, with a 4 barrel Quadajet, when you went to press the pedal, it sound like it was sucking bad, then backfired, I rebuilt the carburetor, and then adjusted it and it ran fine.




Robert

 

[The_Dealer]

carb is brand new, and fuel pump isnt gonna need a reg. gona use holley red said u dont need one