Fuel problems - 75 Johnson

[BeFree]

Have 75 Johnson that I suspect has bad fuel pump. Will start but quickly dies, especially when throttle opened up. Will keep running if the bulb is pumped. Have original gas tank, which leaks from between the outlet assembly and the tank body. Could this have anything to do with the problem? I've had the motor for about 4 years and have never replaced the fuel pump. Any suggestions?

[BonairII]

You def need to fix the air leak. Temporarily run a piece of clear fuel line from the fuel pump to the carb. You will be able to see bubbles in the fuel if air is getting in.

If air isn't present then, yes...your fuel pump could be tired. A rebuild kit is cheap, so rebuilding it is a good idea regardless.

[5150abf]

With the engine off if you pump the bulb and gas comes out anywhere in the line it is a problem, an outboard sucks the fuel to the engine and it will draw air from any leaks before the tank so the system needs to be sealed so yes fix the leaks and if it has been more than 5 years since you put new gas line on it now would be a good time and go from the tank to the carbs.

Fix all the leaks in the line and then try it again, if will only run when you pup the bulb then the fuel pump should be replaced, might be worth your time to check it, I had one and the base cracked btu to just look at it you couldn't tell so maybe pull it off and inspect to make sure it isn't just plugged or something like that.

[BeFree]

Thanks 5150abf (despite being a fan of evil ND ) & BonairII.

Pretty sure I've isolated the problem. Bad O-ring in the fuel-line connector at the gas tank. That was the only place it was leaking along the route of the fuel. Took the connector off, put the end of the line in the gas tank, and pumped the bulb. The pumping action became more firm, which had not happened before. I replaced the line from the gas tank and one of the connectors, which had broken off, but reused the other one. Will now replace it.

The leakage between the steel tank body and the fuel housing is because of a bad gasket not able to resist the vapor pressure buildup in the tank. I just have to decide whether to replace the gasket or buy a new plastic tank.

[BeFree]

Forgot to mention, this is a 1975 25 HP Johnson