Classic/Antique Car Repair: 1926 Lincoln Limo, electric fuel pump, mechanical pumps

Question
We are working on a 1926 Lincoln Limo, the only thing not stock on it is an electric fuel pump has been added. At times it will run perfect, other times it will run rough and backfire. The fuel in it is fresh, when it backfires, it may come out the exhaust or the intake area. Any help would be great thanks.
Brandon

Answer
Sounds like a great project. I have my doubts if the electric fuel pump is the problem, but you can take a volume and pressure test on the pump. It should pump between a pint and a quart a minute and the pressure should be about 4 to 6 PSI. The pump should also be mounted as close to the tank as possible and as low on the chassis as possible. Electric pumps are not puller as are the mechanical pumps but are pushers. Where you have fire coming out of both intake and exhaust I would suspect valve or ignition electrical problems. Have you taken both hot and cold compression tests on the engine? That would be my starting point. Take the test and then get back to me and we will go from there.