still same old prob fump conversion

[vwluv32]

Im working on a '57 18hp rude. I finally got the thing to pump, but it will not keep up with demand of the motor. I have to pump the primer to keep it running, but it will run aprrox. 45s before having to pump it again. This varies a little with the motor speed.
The things that have been done:
new 7350 pump
the stand off pump mount
routed fuel line straight from the tank to the pump
new gaskets for fuel pump mount and fuel pump
new ethanol safe hoses
Im not sure what else could be done. Any input would be great!
vwluv32

 

[oldcatamount]

Re: still same old prob fump conversion

The fuel pump is operated by the pressure created in the crankcase. You may have a crancase seal that is leaking. Check by using a small paint brush with soapy water on the gasket joints. You'll see bubbles if there is a leak. The problem with that test is that the motor needs to be running. You could also try tightening all crankcase bolts to.

 

[F_R]

Re: still same old prob fump conversion

My belief is that if it is running on both cylinders, it has enough crankcase pressure/vacuum to operate the fuel pump.

I think you have an air leak somewhere in the hose between the fuel pump and the level of the gas in the tank. Just a small leak will admit enough air bubbles to kill the pump's suction. A common, but sneaky leak location is around the pins that are pushed in when you connect the hose to the tank.

Another thing is the pump won't work right if installed upside down. You didn't---did you?

 

[vwluv32]

Re: still same old prob fump conversion

I dont have the connector, I eliminated it by going straight from the tank to the fuel pump. As far as the pump being upside down, ill have to get back to you. But since I put it on, probably.
chris

 

[vwluv32]

Re: still same old prob fump conversion

pump didn't work when I turned it. I found a beautiful 1955 15hp w/ the pressure tank and 2 fittings that works great for $200. Bought it. But if any one would know where to get a better cap, I would appreciate them letting me know. I think Ill keep playing with the 18 till I find out what the problem is.
Chris

 

[vwluv32]

Re: still same old prob fump conversion

2 days after I bought the 15, I got the 18 pumping fuel. I went from a 3/8 primer and hose to a 5/16. probably has more to do with new primer bulb
chris