Hey carb guys - what kind of electric fuel pump are you running and would (or wouldn't) you recommend it? This business of wailing on the starter while furiously pumping the gas pedal after it's sat for a couple of days is getting old. Embarrassing too. When there's fuel in the bowls is starts instantly. If I spray the carb it starts instantly... Is it okay to run an electric pump inline with a mechanical one, then rig a pushbutton and only use the electric for priming the carb? Or am I better off getting rid of the mechanical pump, then using a vacuum switch so the electric is only on when the engine is running, and again use a button to prime? I'm a little nervous about just having the pump stay on whenever the key is on, in case of a fire or a wreck, so I'd like it to behave in a way similar to a factory EFI pump. Hope I'm making sense... You know how I over think things.
i got the eldelbrock 120gph pump, its very quiet works well has a internal adjustable regulator. Mallory pumps are really good also. they are the quietest ive ever used. Holleys are loud accept for the hp series pumps. at most autopart stores they have a universial elec pump that looks like a little box about 2 inches square. they work good as a booster pump and should be able to prime your fuel system. they are only around 30 to 40 bucks. you can run them in line with the mechanical pump. i would leave the eletricpump on when the motor is running. the problem with using a vac swith is that it will turn off the elec pump when you floor it.
Mallory on my car, but I got a 70gph, need to step it up to a 110 or higher, don't even know it's running
Pretty much anything 110gph or better will work. Some are loud, but if you mount them on the frame but on rubber grommets, you won't hear it. There have been a few threads about how to mount one quietly. Mine is a Holley Blue 110gph, and works fine. It was quite loud until I put some rubber grommets between the pump and the brackets I mounted it with...Now it is silent.
Mr Gasket P/N 12G or D, 30 gal/hr, 4-7 psi. This is plenty enough to feed three Holley 2 bbls at WOT for 3-4 minutes(at least) on a 400+ hp 331. Quiet, you cannot hear it with the engine running, & just barely with the motor off. Any pump bigger is over kill on a N/A carbed motor. 30 gal/hr translates to a motor getting 2 mpg at 60 mph.
great advice John! but on the subject, im just running a Purolator Solid State Fuel Pump which flows about 65 gph and works really well on my stock 302 ('91 5.0, Edelbrock 500cfm and Weiand 8011 intake) http://www.racerpartswholesale.com/product/1738/Facet_Fuel_Pumps
I'm running that 70 GPH pump @ 6psi idle and run out of fuel to the bowls around 4800, but I have that Speed Demon 650 that still need tweaking
You are pumping .2 gallons through your engine every 10 seconds? 1.2 gallons each minute? - not really, read on.... If you are running out of fuel it may be due to the acceleration. The faster you accelerate the more pressure you need to overcome the mass of fuel in the line. Your pump has to be able to "lift" the fuel to half the height of your line's length vertically. Gasoline weighs about .3 psi per foot in a vertical column. If your line is 12 feet long from the pump to the carb you will need 3.6 psi in addition to what ever pressure you want at the carb. Using the above dimensions and your 6psi pump you are only getting 2.4 psi at the carb under acceleration. I am running two pumps (2 into 1) at the tank (internally regulated at 6 psi) and one in the engine compartment (internally regulated at 4 psi). With 357 cu" at 6000 rpm I never have any problem with fuel delivery. Because I have 4 psi at the engine compartment I keep 4 psi at the carb.
I just LOVE it when PaulS chimes in. None of this "I have it and like it" crap...He gives you the numbers and data to back up his claim. But personally, "I have a 110 gph electric pump, and I like it"...
I would if i were you address the problem of where is the fuel actually going. Most cars can sit for months and still have fuel in the bowl of the carb. I know mine will (Holley). Also on another note on the cranking, Why would you want it to start rite up after sitting for a few days? When mine has sat for a few days i always disable the ignition system and spin the motor till i have oil pressure. After all most engine wear is at start up when the oil has drained from the friction surfaces. Also to properly use a electric fuel pump you need a bypass regulator, To return the unused fuel to the tank. Otherwise you are bypassing in the pump which puts undue wear and stress on the pump. One other note worth mentioning, Most GPH numbers are free flow numbers, When you go to restricting the flow the GPH number falls drastically. Also to remember is that PRESSURE IS A MEASUREMENT OF RESTRICTION. Just because you can maintain pressure doesn't mean you have the volume of fuel your motor needs. IE: You can only pump so much fuel Thur a given line size no matter what the pressure.
You obviously have a restriction problem in the line.The only time my 30 gal/hr pump fails to feed the 3 holleys is when the fuel filter gets plugged. That's when I know when to change the filter.
I don't want to hijack this thread, but I know, there is no restriction in the line. From how I'm reading Paul's post is when I open the throttle, I'm dropping to about 4psi, loose 2 psi under load, so I should really get a pump capable of 8 psi, or run multiple pumps? If I'm reading this right. I don't know where I get the figure to determine the pump size when I got this pump, but its much nicer than the summit cheapo jobby
