trouble shooting help!

[final flight]

i run a 50 hp. 4 stroke. to feed the beast (ha,ha) a have a 12 gal. remote tank.... start out by pumping the ball till it's hard start the motor run out and fish.3-6 hours later i go to come in and the ball is full of air, motor skips and knocks to let me know it's full of air. pump the ball and it runs fine. how do i solve this problem or is it common with the four strokes??? thanks --rollie

[Fishstix]

A good guess would be the fuel tank vent plugged..

Or it could be sucking air around a fitting.

Ive never had that problem with a four stroke.

[Fishstix]

After thinking about this awhile,you may need a Check Valve in the fuel line.

They keep the gas from draining back into the tank.

They are usually installed on the suction end of the fuel line.

Some have a filter or screen built into them.

Always try the easiest stuff first. Its probably something simple.

[LongLine]

You might just need a new bulb. The one I have has a check valve in it. Agree with Stix. "Try the easy stuff first."

The only way it can siphon back into the tank is if some air gets into the line on the engine side of the bulb. Are all your connections tight? An easy way to check for looseness or leaks on the engine side is to look at connections/hoses as you pump the bulb.

Tom B.

(LongLine)