I want to add an electric fuel pump as a back up to my manual pump (mild 350 chevy). I bought a Holley red pump but when I try to blow through it it offers a great amount of resistance. So I figure that fuel will not be able to be pumped through it by the manual unit. Do I need to run a bypass line or is there another pump I can install "in-line" ?????
Sounds like you have it backwards? Generally, you need to install a mechanical pump as a back up for the electric pump But yeah, you won't be able to pull fuel thru a vane type pump like the Holley.
the last 5-6 cars i have built i used a Carter electric pump back by the tank in addition to the mechanical. i switch it so it will only run when needed , never had any problems with the mechanical drawing fuel through them
Tee around the electric pump with a check valve if you think it will be a problem. The check valve will allow the mech pump to draw fuel around the electric, but won't let fuel push back to the tank when the electric is on.
I have had cars where the manual pump will draw through a diaphram type pump but all the pumps seem to be rotary vane types now. Is this the type you use??
IMHO I wouldn't run both at the same time. Just have it mounted up, and some barbed fitting ready to go for when you NEED it. Also, don;t push through a mechanical, if the diaphram blows, then the electric will fill the crank case up
I've been running a solid state 2-3 pound unit for years. Put it on the frame rail just in front of the drivers side rear wheel, block off the mech. pump. Also wire in a relay. I've run em' all and the cheap solid state ones have always worked the best. Go figure. Never let it run to empty. Fastest way to burn it out. I have a merc with a small block so I know from what I speak. -stick
I have an electric pump mounted on the frame rail just in front of the left rear wheel. it has been there for 15 years. i have it on a toggle switch. i have never had a problem
Personally, I have had bad luck when relying on an electric fuel pump as my only source of fule delivery on street cars. Now, most all cars have electric pumps due to fuel injection requirements. Given a choice, I will always choose a mechanical pump because they have proven to be much more reliable, IMHO. I want to add an electric unit as a back up only. Several times, in the past, having a back up has got me home due to vapor lock and dirty fuel filter problems.
I run a late Ford ~40psi injector type pump, w/a Duratec motor and the best item, which might apply to any elec pump, is the motion shutoff. The Ford Focus has it behind the front passenger kick panel. Let it power the pump's relay, then if you stop "suddenly" it will shut down.
Napa part # P74019 , made by carter. it's called a solenoid type and uses a piston actuated by a magnetic coil. i only use for starting if the car has been sitting for a while , not full time. the mechanical pump has no problems sucking through it
I have a TPI pump in the tank from Rock Valley and believe that the PSI will be too high for my Holley 670 Avenger. I do not wish to run the extra line for a by pass. Will adding a regulator to maintain a lower flow rate damage the pump? OR would you add a frame mount fuel pump? What PSI is good? Sorry to ask so many questions, but I do not know the answers. smile. regards, George in Parker,Co. 1948 Ford Coupe with 354 Hemi
I have been Running a Carter Electric fuel Pump for 25 years in my 50 Merc with a SBC and No Problems Just my 3.5 cents
--------------------------- Diaphragm-style electric pumps are quiet. Also, they only come on as needed, rather than running continuously like the Holley and most other actual 'electric-motor' driven pumps. At the most a diaphragm pump will only make a slight 'clicking' noise when it comes on. If you use it as a backup pump, mounted near the tank to feed a mechanical pump on the engine, you'll probably never or only very occasionally ever hear it. Mart3406 ===========================
-------------------- For most applications the stock mechanical pump on the engine will probably suffice. There are some situations though when adding an electric pump back at the tank and using it to feed the mechanical pump on the engine can be helpful though. Years ago when racing my still street-driven 283/4-spd '64 Chevelle at the track, the power would flatten out and fall off above at above 5000 rpm in 3rd gear. It didn't actually 'miss or ''crap out' or anything, but the power just kind of 'went away'. The engine had a solid-lifter cam and good valve springs (it'd easily and regularly pull past 6500 rpm in 1st and 2nd gear) so the problem wasn't valve float. Finally, I figured out the car was starving for fuel under load at WOT. I solved the problem by adding adding a electric pump at the rear of the car near the tank to push fuel up to the mechanical pump and the problem was instantly solved. After that, the car easily pulled through 6000 rpm and beyond in 3rd gear and went through the lights in 4th at about 5500, just starting to come on and really pulling hard. The pump I used was a small 'universal-type' diaphragm-type pump that I had lying around - that by itself, probably would have been inadequate, -but when combined with the also slightly inadequate stock mechanical pump, I had all the fuel I needed. The other situation where an electric pump at the tank pushing fuel to a mechanical pump on the engine can be helpful is if you have a chronic vapor-lock problem. Pumps push fuel better than they pull it and when the fuel is under pressure, as it is on the outlet side of the pump, the boiling point of the fuel is raised substantially. Conversely though, the boiling point of the fuel is also lowered by the same amount on the suction side of the pump and the harder the pump has to work trying to draw fuel through a long and/or restrictive line from the tank, the more the boiling point is lowered and the more prone the engine is to vapor lock. By putting an electric pump at the tank - even a small, low-pressure one - to push the fuel up to the mechanical pump, the fuel in the line on the suction side of the pump, because it is now being pushed there under pressure, rather than being pulled under a vacuum, has a higher boiling point and a greater resistance to flashing into a vapor. Mart3406 ===========================
I never had any luck with the type of pump shown. The rubber bellows always developed a small crack in about 6 months causing the pump to malfunction.
----------------- That could be caused by modern, supposedly "improved" fuel formulations being used nowadays. When I installed one on my '64 Chevelle, that was back in the late-70's-early '80's. I never had a problem with it, but that was then and this is now and fuel is definitely different. It may be a good idea to avoid an older diaphragm-style pump, even if it still works good. There are some newer ones available now though, designed to withstand the 'strange brew' chemical cocktails that pass for gasoline these days. One good, low-pressure, medium-volume pump that comes to mind is the Facet model 40108. I've used these before without any problems. It will handle modern-day gasoline and is quiet, long-lived and reliable enough that it's commonly used in a lot of marine and even homebuilt aircraft applications. Mart3406 ===========================
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