Re: 2000 Johnson Motor 70HP - Fuel Pump Issue?
I have a 2000 60 hp Johnson and never had any problems with it till lately. It problem turned out to be the original fuel pump with VRO. Let me say I am in favor of the VRO and it has been working fine for 11 years but nothing last forever.
The oiler side of the pump never quit oiling, but something went wrong on the fuel pump side. Most of us don't have the tools and test equipment to put these pumps to the test so I did as you did and did all the other stuff first thinking it would be needed anyway cuz I feel I should keep up with my maintenance. The motor started surging at high speed then over time began loosing RPMs until I couldn't get it run fast at all, just act up like crazy. If I pumped the bulb at high speed (when it would run high speed) the motor would slow down more. (found out the pump was leaking inside from the gas side into the vacuum side of the pump, down the pulse tube and flood the bottom crankcase. Same thing would happen when idling, pump the bulb and the motor would stumble and act like it wanted to die. With motor off and pump the bulb it would get tight then while holding the bulb tight it would act like gas was going somewhere, only to find out I was flooding the lower crank case with fuel and later the motor would act like it was locked when I would try to crank it again. (fuel was being pushed into the motor) I would get it to spin and start and eventually clear and the bottom cyl would come alive. My first reaction when I started to trouble shoot was the fuel pump, but the forums and other sites steered me away from the pump and I went looking at other things.
Just replaced the pump with a gas only mechanical pump #438557 (went to premix) and issue solved, all crazy acting symptoms went away. (had to fabricate a mounting plate below the starter) Bulb is tight, pump is pumping, no more flooding. I replaced all hoses, bulb, rebuilt carbs, new plugs, even a power pack ( guess thats OK cuz I will get my use out of it). I was about to pull my hair out on this one. Idle is a little higher now, but I will take care of that next time out.
My advice? If your VRO has some years on it and some of these symptoms start, think about replacing your fuel pump anyway. Do all the other maintaince as well and save yourselves some aggravation. VRO or premix is up to you, the VRO is not something most of us can trouble shoot or rebuild so don't bother, just replace it and don't look back.
I have owned an OMC motor since the middle 60's, done all my own work, and usually solved my problems pretty quick. This one just about got me. Also didn't find anything on the web describing what I went thru.
