1977 Johnson 4HP hard starting

[Hank007]

I have a 1977 Johnson 4HP that has good compression, fires on both cylinders. When I try to start it, it is very stubborn. Will occasionally run for a bit, then stalls. Any suggestions what I might try. I followed the service manual as far as carb adjustment. It did not help. The carb was recently rebuilt as was the fuel pump. ANY suggestions would be appreciated.

 

[tx1961whaler]

Re: 1977 Johnson 4HP hard starting

When it runs for a bit, is that idle, medium or higher speed? Any difference between the speeds?
Does choking the engine affect the running?
Also, if the 1977 has points and condensers and coils, were those replaced any time recently?
Describe how the carb was rebuilt. Was it disassembled, soaked in solvent and all of the jet and passages blown clear.? These tiny engines have equally tiny carb passages that are easily plugged..
Was the ignition spark tested with a spark tester, or a spark plug? Occasionally a weak spark is good enough to jump the small gap of a spark plug outside of the engine, but is not good enough when the engine is under compression....

 

[Hank007]

Re: 1977 Johnson 4HP hard starting

Hello tx1961whaler. It is at idle speed. Choking the engine doesn't seem to affect much. The carb was completely disassembled and soaked. All the nooks and crannies were cleaned and cleared, then reassembled according to the manual. The spark was tested with a plug as no spark tester was available. Do you think I may have a spark issue? None of the coils were replaced. All the electronics were the originals. Thanks for your help.

 

[tx1961whaler]

Re: 1977 Johnson 4HP hard starting

I would confirm the spark with a spark tester first, mainly because most (OK, all) of the coils fail after awhile on these motors (it has been 30 years, after all), and it's the cheapest test you can do, since the tester can be found cheap at an auto parts store.
Once you get the spark confirmed, and since the compression has already been tested, then all that's really left if the fuel system, which is somewhat operational since it will start and run sometimes.
Also, I have a 3/4" socket chucked up in my drill, to keep my arms from falling off pulling on the starter rope.
I have a "new" 1970 6 hp johnny in the same state as yours right now, and I'm planning on redoing the ignition (coils, wires, plugs, points, condensers) and carb as soon as I land a new job and have the play money to do it. I have a 3 hp that I just got done rebuilding from the ground up that runs like a watch, so I have a good kicker already.

 

[Hank007]

Re: 1977 Johnson 4HP hard starting

Wow. Thanks for the advise about the drill. Works like a champ to save my arms.