I need some opinions on electric fuels pumps. I have a performance mechanical holley pump with a gauge installed in the line. The pressure varies so bad I not sure what to think. This is the second mechanical pump to do this on me but it starts out when cold at 7.5 - 8 pounds almost too much. When the engine gets up to operating Temp and the under hood temps get up there at extended idle I have seen the gauge between 0 -1 pounds. This really screws up my float settings, they are almost too high at start up and when hot with the low pressure the fuel level looks too low thru the sight holes, this pump is supposed to be rated at 7 pounds?? I have never seen the engine starve but it does not look consistent with the pressure. Am I on the edge of vapor lock?? Should I just go to an electric pump? I like the idea of a mechanical becuase its quiet, already in place, and my electrical system has barely enough as it is but maybe I should consider electric?? I don't understand the pressure readings variance?? Suggestions? Input?
i'm not to sure whats going on with your pump now. but if you want quite DO NOT get a holley blue! its loud as heck.. i know i have one. but i don't care about the noise. if you want an electric one i'd get a mallory i think its 10xs quiter then a holley blue and would match what you are in the need for. now i'm sure there are better ones but for what you need it think the mallory will work. good luck
Cheap or functional I agree about the Mallory, they are pretty quiet. But, when the go out, lotsa fun to rebuild. I had a hard time finding rebuild kit. If you are running a close to stock setup, you might think about an Autozone electric with rubber isolators. The pump is cheap and puts out peak dead head presure of about 8 psi. If you really want the Mech. pump, try putting some heat wrap around it, or even some ducting of freash air, like on brakes, to help cool it. I have used the Carter mech. pump, but prefered electrical. It's cheap, and lifetime warrented.
Maverick Man Couple of questions about your holley Blue. Are you using the factory lines up to the engine bay or are you running a seperate line back to the tank? Are you using regular clamps/holes or is it run with higher pressure hoses/AN fittings? Are you using a relay? How did you wire yours? Are you running filter the fuel before the pump? I like the idea of quiet but my exhuast is loud enough that you probably could not heard it and the Holley Blue comes with a regualtor and is much cheaper than the mallory. My only concern is the Holley makes 14psi and I was hoping to use most the factory setup back at the tank until I get to the engine bay but was a little concerned about 14 PSI with regular clamps but I guess that should be ok with all good hoses and clamps. Sorry for all the questions. Thanks for your time.
Have you checked your rubber connector hoses...The colapse when the get old and hot. Could be your problem. Robert
The only time my Holly blue was quite was when the battery was disconnected. I even bought a high dollar Paxton to replace it and it wasent much better. I dont think there is such an animal as a quite aftermarket electric fuel pump.
Robert All but one piece of the existing fuel line is new. The small junction on the underside of the car -- under the driver's door has not been replaced. It is small and feels hard as a rock -- I would think it would leak before it would vacuum shut. Thats a good point though I have never looked at the hose that come thru the fender apron while this is happening although the hose is new there. What I think rules this theory out is I can run down the Interstate with the 4 barrels of my 670 Street Avenger open and the car doing 80+ for miles and it never starves out?? My car is still running lean but if a hose was sucked shut I would think I would flat out die as this thing drinks gas massively
ok answers... i'm not running stock lines anywhere i used all AN fittings... use either nickel plated ones or the eudura ones. alum ones really suck and strip easy either on or off. the guys at mallory told me.. "why do you think we included brass fittings? 90% of the time your either strip the alum ones when your putting it on or taking if off" i just laughed! back to the tank.. nope and never had a problem without it either... that pumps and regulator has been on the car since 1988 or so! oh well. a relay.. doh.. whats that? yeah it should be... but its not... its hard wired to a switch.. not exaclty safe... i'm changing that though before i take it our again. yes i have a filter b4 the pump.. i woundn't run it any other way... but thats just me. as far as your set up... i'd jsut get a holley mech pump. i can't remember if i said this already but my friend down the street runs with a 347 high 10's with a holley mech pump on the juice too... he's never had a problem.. well at least yet..
7.5 - 8 psi is too high for your Holley carb. Some of the Holley mechanical pumps require a regulator to get the pressure down to about 6 psi for a street engine. With out a regulator I've heard of them lifting the carb's needle valve right off the seat. That could definitely cause pressure fluctuations. Is your pressure gauge before or after the fuel filter? Maybe it has some debris floating around inside.
I have worried that the pressure is too high. I talked to Holley and they said nothing past 7.5. In the first 15-20 minutes it seems I can contol the float level. Its when she gets roaring hot under the hood with outside temps above 85 or so that my pressure falls flat and the float level drops. The engine does not really run much different( I am running lean but I am in the process of rejetting - thats a different story altogether and runs lean hot or cold) Anyway I am once again going to try to change the gauge to one that is not liquid filled - I heard that the heat really affects their accuracy. The guage and all the line is new and after the filter. If the new gauge gives me a better reading I will either try a regulator with the existing system or change over to a electric pump. bmcdaniel -- what kind of pump are you running?
I have an Edelbrock 1725 mechanical pump. I'm adding a Carter P4389 electric pump that comes on when the nitrous is switched on.
Thats pretty much how my setup works...I have a Carter high-volume mech pump and I have my Holley maxpump hooked to a switch(though a relay of course) in the car. That way I only have it on when I need it....its noisy enough to drive me nuts(too late maybe).
