I'm hoping someone can help me troubleshoot the issue with my 1986 Johnson 4 HP Model No. J4BRHCDE. This is the issue:
starts and idles fine. If throttle is increased while not in gear
, sounds like the motor
revs up fine, but donít know actual RPMs so canít know for sure if it is really at max RPM
. When in gear
, and throttle is increased (it is a slide on the front of the motor housing, not a twist on the tiller) the motor rpm
comes up, but does not increase as much as it should for where the throttle is. For example, when it is full throttle it is only about half the rpm used to run. Motor seems to run fine and I donít notice any unusual vibration, it just runs at a lower rpm than it should. Then, from time to time, while I am running along at full throttle/half rpm, the motor will suddenly go to full rpm. It sounds to me like there is a ďclunkĒ in the motor at the same time (and every time) it goes to full rpm. The motor will then run fine at full rpm until next time you throttle down. Then, you are back to full throttle/half rpm situation.
I suspected it was a throttle linkage problem. It has a cam/roller wheel
assembly, and when I pulled the cover and inspected it the roller wheel
is a little wobbly but it looks like it is always bringing the carb to full throttle, so now Iím wondering if it is a carb problem (something stuck in there is obstructing fuel
flow almost all of the time) or an ignition problem (only running on one cylinder most of the time, but occasionally the cylinder fires).
Anybody ever had this happen?