Adding a "booster" electric fuel pump for easier starting ?

I have heard of people adding a small electric fuel pump to prime their fuel lines for cars that sit for extended periods. I understand the principle, but...
If the car has a mechanical pump, can the electric pump actually push fuel though it? I thought the mechanical pumps only allowed fuel through as they open and close. What if the electric pump is running while the mechanical is off the pump stroke? Please pardon the ignorance, I just do not understand.
Also, in the case of a "drift car", I've seen them fitted with a large brake lever near the floor shifter. These are plumbed to the rear brakes to initiate a skid to get the rear of the car to slide. These are often plumbed using a master cylinder near the large hand operated lever. Does the firewall master cylinder have a check valve to prevent fluid and pressure from pushing out of the reservoirs?

Running an electric in series with a mechanical is no problem at all. Been recommended since the Direct Connection days.

As far as drift cars.. hate em. So no comment.

Hey, fast American cars can be made to drift, it isn't just ricer boys!

It is for the ricers. If I wanna 'drift' I'll give her 1/2 throttle.. e-brake need not apply.

http://www.driftworks.com/hydraulic-handbrake-package.html

Thanks Oz, I see that they show that the standard rear brake line is eliminated.
By the way, The drift brake question was just hypothetical. I am not converting the Charger to a drift car! I was interested in the hydraulic function of the rear brakes. Seeing that the rear line is rerouted to only operate through the handbrake surely makes a mod like this unsafe for the street.

On the pumps, the mechanical pump has a check valve that will let fuel from the electric flow freely.

The reverse is not always true. The electric can restrict or block flow to the mechanical... it depends on the particular pump. I have plumbed in a check valve around the electric when I want the mechanical pump to be the "primary" to make sure there is minimal restriction on the suction side.

I agree as well. I did this a few years ago for my Road Runner. The mechanical pump takes very little (.5psi) to lift the seats and allow the gas to pass right through. I tested my Carter electric pump and it depended on how the vanes were oriented when the pump stopped whether fuel could pass through or not. I rigged the electric with a check valve in parallel so when I turn the electric pump on it pushes against the check valve and diverts the fuel forward to the mechanical pump and up to prime the carbs. When the electric pump is off the mechanical pulls fuel though the check valve (least resistance) straight from the tank. This arrangement has been working great for the past several years. I run the pump about 20 seconds, it changes tone when the carbs are full. Hit the gas to set the choke and the car fires right up. Much better than opening the hood, remove the air cleaner, fill a squirt bottle with gas, fill the carbs through the vent tubes, put everything back together and crank it over until it catches... Usually this was with an audience who did not understand the issues of today's ethanol blends.

Or you could just eliminate the mechanical pump and use the electric pump all the time. I cannot understand why you all are so married to the mechanical fuel pump!

FD, the mechanical fuel pump has two check valves, one in front of the pump and one behind it. Both are oriented the same direction. When the fuel pump cam pushes the fuel pump lever away, it sucks fuel in through the "rear" check valve into the diaphragm chamber. Then the spring that pushes on the diaphragm pushes the fuel out through the "front" check valve and up into the carburetor. That's why some times when you pull the fuel line, fuel spurts out. The fuel pump is emptying. Stronger spring = more fuel pressure at the carb. An electric pump., really any kind of pump, will pump fuel through the mechanical pump. If the diaphragm fails, the electric pump will pump the oil pan full of gas.

R.

https://board.moparts.org/ubbthreads/ubbthreads.php/topics/658312/1.html

Thanks everyone. Good info and I appreciate the help.

I have one on my car , works good , just flip the switch under the dash and instant prime.

I found an electric timer relay, turn ignition on, relay turns on, 5 seconds of prime, relay turns off, turn ignition off then turn on to get it to run another 5 seconds. Put a rattle pump parallel to a check valve and you are in. Pump only runs at start up. Tim

That is a good idea.

You guys have some great ideas. I like my cars pretty much stock looking but both my RR and AAR have electric pumps (got em that way) and are always easy starts! Just turn on the key and after a few seconds pump the carb few times and they start right up. My other cars require multiple starts almost to the point the battery is done if they haven't ran in awhile. BUT the fuel pumps are very loud, so I'm liking the idea of initial usage and then let the mechanicle take over.

So the purpose of even keeping the mechanical pump is for factory looks? My Charger is heavily modified and I just run an electric pump and have been for several years now. I have never thought about any reason for both.

I am using a mechanical pump that is supposed to be good for 2000 horsepower, Racepumps 2000, but it does not prime itself. I just don't like electrical pumps. Too many failures when I needed them. Tim

I don't like the noise of electric pumps. Yeah, I know that sounds UNmanly, I just hate buzzing sounds. Those stupid curly light bulbs for home use buzz and it annoys me too.

I used one like this mounted inline before the mechanical pump.

http://www.napaonline.com/napa/en/p/BK_6101074/BK_6101074_0498432605

I turned it on with a switch before starting and then turned it off. This is probably not a viable set-up for a car that needs LOTS of fuel flow but it worked fine on my 440 max-wedge look-alike street driven car.

I can't stand the electric pump whine, it's really loud on my RR but I do like them for quick start up. My RR still has a stock pump on it that I assume is still working also. I simply need to interrupt the electric pump with a switch I can momentarily turn on at start up instead of being on all the time. My AAR has a block off plate with no mechanicle pump but easy fix assuming the eccentric is still there. The electric pumps are both mounted near the fuel tanks and you can't even see them to retain my stock look.

been reading this topic , with interest , would appreciate any information , does any one know , what make & part number electric fuel pumps when switch off ! eg , that would be used as a priming pump , allow fuel pull through , by the mechanical pump ? would have thought electric pump makers would have supplied that information with pump specs etc , seem to remember this cropping up in a thread some years back , was soo long ago , I cant really remember

thanks in advance for any input thoughts ....

What if there was a product that you could add that would not only supply fuel to the carb before the engine starts (for easier starting), but would also be able to feed a carbed or fuel injected engine up to 1000 hp (on gasoline) while still using an otherwise completely stock fuel system?

http://www.robbmcperformance.com/products/powersurge.html

Yes, it really works. The only limitation is that you can't go full throttle continuously for more than one mile at a time. But if you are driving a street or drag race car, how often will you hold the gas pedal to the floor for more than a mile?

Hey, that looks like a great idea too. Thank you !

I had a few PMs asking about the check valve shown in the picture. It is an Earls item, P/N 251008ERL, I got it either at Jegs or Summit. The pump is a Carter #P4070, I used it because it did not require an additional regulator - the pumps are rated 5-7 psi. I used #8 AN fittings (1/2") to reduce any potential plumbing resistance. I tried to make mine as simple as possible but still be neat. You can surely save some money by going with some generic fittings. I can't remember if these were Russell or Earls. If you go with the AN fittings just mock everything up loosely then you have to put a slight twist in the assembly to get it snug. I located the bracket in the axle tunnel using locations that were already there so no need to drill extra holes. One hose come up from the gas tank and the other hose connects to the fuel line on the frame. Everything fit just fine even with the Dana 60. Years ago on this forum I had supplied a full list by part # but can no longer find it...

I would run a line on the inlet side from the electic pump to the line between the mechanical pump to the carb. with a check valve to prevent drain back from the mechanical pump
That way it will fill the carb. every time you use it instead of having to rely on the valves in the mechanical to be open to allow fuel to flow upwards to the carb.

thank you for the replies & pictures etc