bloatedboatone
Recruit
- Joined
- Apr 5, 2009
- Messages
- 2
I bought a 1987 Johnson 28 this past winter. It was in nice shape and belonged to an older gentleman who had obviously taken good care of it. He used it at a cabin on a remote lake and said it would run fine for awhile, then die, refuse to run at open throttle, and then suddenly run fine again. His family was distressed by the repeated problem so he swapped it out for a new 4-stroke. He had done the following in an attempt to fix the problem:
Replaced the fuel pump, filter, all the hoses, rebuilt the carburetor. Replaced the electronic ignition control, both coils, wires, plugs. The shop where the motor was taken reportedly could not reproduce the problem - I assume it ran well for them.
I converted it to a short shaft, replaced the water pump, and ran it for the first time this spring on a 14' Duroboat. All new wiring, by the way. It wouldn't respond to open throttle - would only idle. I tried pumping the bulb, changing the lever on the solenoid, etc. with no improvement.
I pulled the carburetor and installed a rebuild kit, including new float (carb looked clean). I installed new plugs (old plugs both black - one with clean white spot at end of electrode, other black - swapped plugs - didn't make a difference.Tried .030, then .040) Compression measured 115 each cylinder. Checked the synch - okay.
It starts immediately, as before. Runs smoothly until the throttle is opened, then revs well at first before backfiring and missing. Misses and runs rough at idle afterward. Tries to die when given any throttle.
Reed valve problem? Any suggestions are welcome.
Replaced the fuel pump, filter, all the hoses, rebuilt the carburetor. Replaced the electronic ignition control, both coils, wires, plugs. The shop where the motor was taken reportedly could not reproduce the problem - I assume it ran well for them.
I converted it to a short shaft, replaced the water pump, and ran it for the first time this spring on a 14' Duroboat. All new wiring, by the way. It wouldn't respond to open throttle - would only idle. I tried pumping the bulb, changing the lever on the solenoid, etc. with no improvement.
I pulled the carburetor and installed a rebuild kit, including new float (carb looked clean). I installed new plugs (old plugs both black - one with clean white spot at end of electrode, other black - swapped plugs - didn't make a difference.Tried .030, then .040) Compression measured 115 each cylinder. Checked the synch - okay.
It starts immediately, as before. Runs smoothly until the throttle is opened, then revs well at first before backfiring and missing. Misses and runs rough at idle afterward. Tries to die when given any throttle.
Reed valve problem? Any suggestions are welcome.
