Electric Fuel Pump Question

[Scott Salmons]

Been having some problems with the 720 and thought I would try to install an electric fuel pump to see if it helped. The main problem is fuel leaking into the crankcase and the other is that the tractor has been running poorly. I finished the install tonight and thought that all was good, started up and ran pretty good still had a slight miss but I needed to clean the drive so I pulled out of the garage and she started running crappy again, it was like the choke was closed. I pulled the plugs and they were black and wet, cleaned them and started it back up ran good for a while then crappy again. Due to the cold temps I pulled it back into the garage and gave up. Could the electric pump be forcing to much fuel? Do I still need a fuel shut of valve to solve the fuel leaking into the crankcase?

[wilm169]

The fuel pump should be one that pumps a rate of 1-5 lbs. If it leaks into the engine you should disconect the old pump and pipe around it. you may have to readjust the carb.

[Cityboy]

It could be that the float in the carburetor is not closing the needle adequately. I did this conversion on my 720 and it works great! Sounds as if you are getting too much fuel now, especially if the pump is too strong. I know that I used a very low pressure pump that I bought at O'Reilly's. Good luck! Dave

[MPH]

Had the same problem on my 4040. When I hooked up the electric I used the same plumbing, including the by-pass back to the tank. If you did not your pump may be forcing fuel though the carb.

[Scott Salmons]

Yes I used the same plumbing with the bypass to the tank.

[D-17_Dave]

It's obvious that the fuel pump diaphram came apart. Common on these older pumps. Only 30+ years on these things and the take a dump. Go figure... If you didn't do a complete cleaning of the fuel system, carb inlet, elbows, bypass orific,etc. some of the debris from the old pump can collect and stop up the float needle and keep it from seating or worse, from getting any fuel. It can also stop up the return and overpressurise the carb. Yes, you'll need a fuel shut off. I find anything over 2/3rds of a tank and it will syphon into the engine.

[Scott Salmons]

I got it running. I drained the old contaminated oil (gas), changed the plugs and installed a shut off valve. I think the crankcase was so full of oil and gas that it was leaking into the combustion chamber. Thanks for all the input.