Primer Bulb not Pumping Fuel

[Snowfish]

96 Merc 60hp 3 cylinder. Primer bulb not pumping, so I replaced it. Still the same. It's not filling the carbs with fuel. Pulled the carb plugs to check....nothing. Engine will start, but sometimes pretty difficult. Even after it starts, and runs good, it will bog out, die on occasion, or just pick up and run great. When it dies, I play with the primer, choke, fast idle, etc and it will start. Let idle, and feather the throttle and we're back in business. Then it will run like a champ for a long time. Maybe even the rest of the outting.

Impulse line appears OK. New fuel filter last season.

Is there a check valve in the fuel pump? Or is the pump just ready to be replaced? Open for ideas.

Past seasons I've only had to use the primer bulb at the start of the season. Then just choke a little, and we're good to go after that.

 

[schematic]

Re: Primer Bulb not Pumping Fuel

if your primer bulb doesn't pump fuel, look to lines and fittings going to the tank. There may also be a anti-syphon valve between the bulb and tank that will restrict fuel when clogged. The pickup in the tank may also be sucking air.

The primer bulb is telling you that the problem is between the bulb and tank.

 

[Snowfish]

Re: Primer Bulb not Pumping Fuel

Both tanks react the same. Twin tanks with manual selector valve. Still questioning the fuel pump, but not sure. Thanks for the reply.

 

[Snowfish]

Re: Primer Bulb not Pumping Fuel

Fuel pump was shot. I'll post pics in the morning.

 

[Snowfish]

Re: Primer Bulb not Pumping Fuel

Excellent tip on checking the tank lines first. However, if the lines are not corrupt, the fuel pump could very well be the problem.

Here's what was found.....................



Not a pretty sight.

Pump diaphragm was deteriorating rapidly.



Impulse side didn't look to bad.



Check valves were completely toast.



Replacements are plastic, not rubber.

This looks to be the original pump. Age and alcohol poisoning is the prime suspect of the pumps demise.

Amazing that this even ran at all! Runs great now, aside from an upper mid to high range stutter. Full carb cleaning, is in order now, due to ultafine black rubber particles making it past the fuel filter. Jets are more than likely partially clogged.

Primer bulb becomes firm when needed. Which traditionally is only at the start of the season. A little more tweaking and we should be back to normal.