Green Diamond fuel pump issues.

Greetings,

I am having a lot of issues with my 1949 KB-5 with a Green Diamond and it's fuel pump. The pump has been rebuilt professionally once. It still gives me fits. So, I decided to try an electric pump. My system is still 6V with a positive ground. It has been modified to 8V by the previous owner. I bought 2 of the cheap electric pumps for 6V but one didn't work right out of the box and the second lasted barely longer than that. I spent some money and got an expensive 6V Carter electric fuel pump. It doesn't want to work either. In my opinion I must be somehow hooking it up wrong electrically with the positive ground system. What is the proper way to hook up a 6V pump that was designed for negative ground to a system that is positive ground?
The next question is: Is there such a thing as a mechanical fuel pump available anymore?

Thanks in advance.

Then and Now in Weymouth, MA can do a bang up job on rebuilding mechanical pumps. That being said I think you may have other problems if 3 electrics lasted only a short time.
The Carter electric rotary pump I know has separate + and - terminals and can be wired for either polarity, You just connect the + to the chassie for + ground.
possible pin holes in the tubing or rust in the tank are what I would look for. I'd run new line from the tank to the pump and inspect the tank.

I agree with Cornbinder that rebuilding the original pump is a good option and better than finding a new one or going electric. What is the problem you are having? Will it not pump at all? Or run out of gas when driving? Or? I also agree that clogged or leaky lines will.cause issues. Also make sure you run a vented gas cap.

The pump worked OK last summer, then I parked it for the winter. At some point over the winter the case halves started to leak. It actually drained the entire fuel tank onto the ground, one drip at a time. When I tried to start the truck the pump was unable to push fuel up-hill into the carb (lack of fuel easily observed through the inline fuel filter). Turning the truck over it would just leak out of the case halves onto the ground. My theory is that it took less pressure for the pump to push fuel out of the case than uphill into the carb. I took the pump apart and played with it many times and just couldn't get it to stop leaking. It has recently been rebuilt (two or three years maybe) so I was hesitant to spend the money on it just have it fail again, hence the desire for an electric pump. After spending numerous hours fighting this I never did get the electric pump to work but the mechanical pump started pumping right when I was about to give up. This one has me baffled!

Maybe look for a replacement mechanical pump that can be rebuilt. Donrun non ethenol fuel in it?