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.

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.

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.