Electric Fuel Pump Install Diagram 2 Pumps
Electric Fuel Pump Diagram
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Click to expand.-Diaphragm-style electric pumps are quiet.Also, they only come on as needed, ratherthan running continuously like the Holleyand most other actual 'electric-motor' drivenpumps. At the most a diaphragm pump willonly make a slight 'clicking' noise when itcomes on. If you use it as a backup pump,mounted near the tank to feed a mechanicalpump on the engine, you'll probably neveror only very occasionally ever hear it.Mart3406. Click to expand.-For most applications the stock mechanicalpump on the engine will probably suffice.There are some situations though whenadding an electric pump back at the tankand using it to feed the mechanical pumpon the engine can be helpful though. Yearsago when racing my still street-driven283/4-spd '64 Chevelle at the track, thepower would flatten out and fall off aboveat above 5000 rpm in 3rd gear. It didn'tactually 'miss or 'crap out' or anything, butthe power just kind of 'went away'. The enginehad a solid-lifter cam and good valve springs(it'd easily and regularly pull past 6500 rpmin 1st and 2nd gear) so the problem wasn'tvalve float.
How To Install Fuel Pump
Finally, I figured out the car wasstarving for fuel under load at WOT. I solvedthe problem by adding adding a electricpump at the rear of the car near the tank topush fuel up to the mechanical pump and theproblem was instantly solved. After that, thecar easily pulled through 6000 rpm and beyondin 3rd gear and went through the lights in 4th atabout 5500, just starting to come on and reallypulling hard. The pump I used was a small'universal-type' diaphragm-type pump that Ihad lying around - that by itself, probably wouldhave been inadequate, -but when combined withthe also slightly inadequate stock mechanicalpump, I had all the fuel I needed.The other situation where an electric pump atthe tank pushing fuel to a mechanical pump onthe engine can be helpful is if you have a chronicvapor-lock problem. Pumps push fuel better thanthey pull it and when the fuel is under pressure,as it is on the outlet side of the pump, the boilingpoint of the fuel is raised substantially. Converselythough, the boiling point of the fuel is also loweredby the same amount on the suction side of thepump and the harder the pump has to work tryingto draw fuel through a long and/or restrictive linefrom the tank, the more the boiling point islowered and the more prone the engine is tovapor lock. By putting an electric pump at thetank - even a small, low-pressure one - to pushthe fuel up to the mechanical pump, the fuel inthe line on the suction side of the pump, becauseit is now being pushed there under pressure,rather than being pulled under a vacuum, has ahigher boiling point and a greater resistance toflashing into a vapor.Mart3406.
Click to expand.-That could be caused by modern, supposedly'improved' fuel formulations being usednowadays. When I installed one on my '64Chevelle, that was back in the late-70's-early'80's. I never had a problem with it, but thatwas then and this is now and fuel is definitelydifferent. It may be a good idea to avoid anolder diaphragm-style pump, even if it stillworks good. There are some newer onesavailable now though, designed to withstandthe 'strange brew' chemical cocktails thatpass for gasoline these days.
One good,low-pressure, medium-volume pump thatcomes to mind is the Facet model 40108. I'veused these before without any problems. Itwill handle modern-day gasoline and is quiet,long-lived and reliable enough that it'scommonly used in a lot of marine and evenhomebuilt aircraft applications.Mart3406.