Can you Troubleshoot a Fuel pump?

[Overdraw]

Just bought an 86 Johnson 25hp. 1st time out fired up, warmed it up for a couple minutes, and then got up on plane. Everything was right in the world. It started to loose power, and I backed off the throttle and it died. After that, it wouldn't take any throttle. We had to limp back to the launch

Engine would start and idle every time, but if you gave it any gas after it was in gear it would stall. Either I sucked something up into the carb from the old cruise tank, or the fuel pump gave way. (Boat has been sitting for 3 yrs.)

How do you troubleshoot this scenario. Can you test a fuel pump, or do you just "Replace and Pray"? Thanks for the advice in advance. --Overdraw

 

[kenmyfam]

Re: Can you Troubleshoot a Fuel pump?

Welcome to iboats.
Is it electric start ????

 

[wilde1j]

Re: Can you Troubleshoot a Fuel pump?

When the motor sags, either pump the primer ball or actuate the choke. If either improves the running, fuel starvation is taking place. The pump can be checked by removing the outlet hose, then pull or actuate the electric starter (if you have one). VERY IMPORTANT: if you have a kill switch, actuate it prior to testing the starter. I would also recommend pulling the spark plug boots off as well. A good pump will shoot strong spurts of fuel. Anything less is a bad pump. An alternate method is to rig a test gauge in the pump outlet line. Your shop manual will give the pressure to expect (normally ~ 3 to 5 psig).

 

[kenmyfam]

Re: Can you Troubleshoot a Fuel pump?

When the motor sags, either pump the primer ball or actuate the choke. If either improves the running, fuel starvation is taking place. The pump can be checked by removing the outlet hose, then pull or actuate the electric starter (if you have one). VERY IMPORTANT: if you have a kill switch, actuate it prior to testing the starter. I would also recommend pulling the spark plug boots off as well. A good pump will shoot strong spurts of fuel. Anything less is a bad pump. An alternate method is to rig a test gauge in the pump outlet line. Your shop manual will give the pressure to expect (normally ~ 3 to 5 psig).

And do it in the water or on the muffs with the hose running to save the impeller.
Strong consistent spurts of fuel = pump O.K.
Strong to begin and tapering off = pump beginning to fail
Trickle to dribble or nothing = failed pump.

 

[Solittle]

Re: Can you Troubleshoot a Fuel pump?

If it has been sitting for 3 yrs. I would rebuild the carb. Your symptoms point to crud in the carb.

 

[kenmyfam]

Re: Can you Troubleshoot a Fuel pump?

If it has been sitting for 3 yrs. I would rebuild the carb. Your symptoms point to crud in the carb.

Can't disagree with that.

 

[Overdraw]

Re: Can you Troubleshoot a Fuel pump?

Thanks for the info guys. I'll test the fuel pump today, and I'm dropping the old girl off to my buddy to rebuild the carb if that doesn't work.