83 Mercury 90 HP (tower of power) fuel pump question

Hi everyone. My 83 TOP seems to be running really well, however when i stop and fish for a while, when I go to start it I find that the fuel has drained out of the line back into the tank and I have to pump the bulb again.

I have purchased a 5.oo one way valve to put in line but someone told me it is likely the fuel diaphragm leaking. I hunted down a kit but I also noticed a check valve listed among the parts on the exploded fuel pump view.

Does anyone know which of these I need? the diaphragm or the one way valve?

need to post your model number or serial to be sure. But if your going to rebuild the pump get the check valve assembly, which usually includes the diaphragms in the kit.

the serial number is 6247291

If it is draining back to the tank there is a problem with your primer bulb also, it should act as a one way valve also.

I thought the same thing and replaced the bulb. Didn't fix it. I am talking after an hour or more in one spot this happens.

Are you tilting the motor forward when you stop to fish? If so the carbs will drain themselves out because the floats and float bowl is no longer sitting level.

Anti siphon valve?

No, I do not do this.

The fuel pumps are simple and the diaphragms are hard to come by for a tower of power. Great motors and they last a long time on the older ones.

I have had new primer bulbs that were bad a couple times, also some of them only have 1 valve to keep fuel from returning to the tank, the better ones have 2 and work better and last longer.

Any slight fuel hose leak between the bulb and the carbs will allow the bleed down. I first eliminate the quick connector for the fuel hose.