Hi everyone. Seeking some help with my 1985 Johnson 40 HP outboard, electric start tiller steer (J40TELCO). I had it out for the first time this year - a multi-day trip. It ran great. Started right up, idled perfectly. Throttled up through the full RPM range and ran at wide open throttle like it was brand new. This continued throughout the next 3 days - full, long days, with lots of idling lots of WOT. Lots of starts and stops. Never missed a beat. On the 4th day, the motor ran perfectly out to the spot. Then, a couple hours later on the way back for lunch, it suddenly would not throttle up. It also had a “cough” or “sneeze” that seemed to happen at low speed or high speed - except I couldn’t get to “high speed” any more. I don’t have a tach but it was easy to tell the RPMs were greatly reduced.
Since then, I have rebuilt both carbs, replaced all fuel/vacuum lines from the carbs back to the primer solenoid. I’ve checked the fuel tank, fuel line, and bulb, that holds pressure perfectly.
I’ve traced for leaks and see no fuel coming out anywhere. I’ve triple checked all fuel/vacuum line connections.
No change. The motor starts right up, every time (so to me that means not an electrical issue). It idles great but then will not throttle up properly when I advance the throttle. Too much throttle will cause it to die. I took the air box off and ran it. There is fuel spitting out of from the front of the carbs (both). So it seems like it’s choking out from not enough air. Does that seem right to you all? If so, please help me understand what my next steps are.
If not, please help point me in the right direction!
Thank you!
Frustrated
Since then, I have rebuilt both carbs, replaced all fuel/vacuum lines from the carbs back to the primer solenoid. I’ve checked the fuel tank, fuel line, and bulb, that holds pressure perfectly.
I’ve traced for leaks and see no fuel coming out anywhere. I’ve triple checked all fuel/vacuum line connections.
No change. The motor starts right up, every time (so to me that means not an electrical issue). It idles great but then will not throttle up properly when I advance the throttle. Too much throttle will cause it to die. I took the air box off and ran it. There is fuel spitting out of from the front of the carbs (both). So it seems like it’s choking out from not enough air. Does that seem right to you all? If so, please help me understand what my next steps are.
If not, please help point me in the right direction!
Thank you!
Frustrated
