20 hp Johnson

[jonmac]

Went fishing today and my motor ran good going to the fishing area also idled around the area good. But on the way back to the ramp it ran like it was not getting enough fuel and it would not get on plane even after I squeezed the primer bulb. The primer bulb was not hard and I squeezed it twice . When I got it on the trailer I unhooked the fuel line like always to run the fuel out of the Carb and it died instantly.

After thinking about this I am wondering if the fuel pump has gone bad. When I pulled the hood off all around the fuel pump was wet and smelled of fuel.
I have never replaced the fuel pump and have owned this motor for about 3 to 4 years. I felt the plug wires and did not notice any obvious nicks or cuts so don't think it is a firing issue.

My question is does a fuel pump work a little bit or does it just go bad and doesn't run at all?
And what else should I look at?
The hose from the tank to the motor is black if that makes a difference.

Thanks for any help.

Jon

 

[DaleH]

When running though, your primer bulb should not be pulled flat and you should feel it pressurized. The arrow on the primer bulb (in reality, it is a check valve) needs to be pointed towards the OB and for best results, the fuel line or end towards the OB should be higher than the rest of the line feeding it. FWIW the OMC bulb is arguably the BEST in the industry, where even the Merc pros on the Scream & Fly forums (i.e., hot rodding OB motors) use them. I'd never run a Moeller or Tempo brand primer bulb myself ...

Bulb - You can diagnose if the bulb is shot or if the tank vent has an issues, but running with the fuel cap open. If the bulb stays firm and pressurized there, then the tank vent could be clogged, i.e., the tank can't provide fuel to the OB if the tank can't replace the fuel it is delivering with air to take up the volume in the fuel tank. Be aware you are leaning out your motor here, if this is happening ...

Pump - If your primer bulb and tank are OK - to diagnose a fuel pump, take it for a good run and if squeezing the bulb keeps the motor running, then chances are there's a pinhole leak in the diaphragm of the pump.

 

[Pappy]

The primer bulb will NOT be pressurized while the engine is running. The primer bulb is on the suction side of the pump!
When hand priming, the bulb WILL be pressurized once the float in the carb rises and closes off the float needle.

The clue here is that you see fuel around the fuel pump.
A very simple test for you.
Remove the fuel pump from the side of the engine. Leave all fuel hoses attached.
Squeeze the primer bulb.
Is there fuel coming out of the hole in the pump that lines up with the hole in the gasket the pump mounts to?
If so you have a ruptured diaphragm in the fuel pump and by squeezing the primer bulb while the engine was running you were forcing even more fuel into the engine and somewhat flooding it.
Let us know.

 

[jonmac]

Thank you for the help I will try the fuel pump test.