Problematic Johnson 120hp

[Pokertrampp]

I have a 1988 Johnson 120hp (J120TLCC), it has been giving me trouble for some time. it has a signifigant mis and it seems to come and go and go from one cylinder to another. This is what has been so far:

1) Rebuilt Carbs 3 Times
2) Replaced Coils
3) Checked Stator and Timer Base (both check out ok)
4) Changed Spark plugs and plug wires
5) Checked Compression (100+ on all cylinders)
6) The motor is NOT charging the battery, I have orderd a new rectifier, should be here any day. when The battery is low I can turn the motor but do not get any spark on any cylinder, if I charge the battery I get spark on all cylinders, is this normal? I thought you were supposed to be able to pull start it with a rope even if the battery is dead. could this be the cause of the mis, the mis is there even if the batter is fully charged.

 

[Pokertrampp]

Re: Problematic Johnson 120hp

???

 

[nymack66]

Re: Problematic Johnson 120hp

My take is fix what you know is broken then re-post the results, obviously the number 6 issue can be a factor..

 

[Pokertrampp]

Re: Problematic Johnson 120hp

Thanks for the input.

 

[ezeke]

Re: Problematic Johnson 120hp

The ignition will not fire until the flywheel reaches a minimum cranking speed, usually considered to be 250 to 300 RPM. That requires a fully charged, powerful battery with clean connections and good cables.

After your annual de-carbon treatment the recirculation check valves are almost always fouled and should be serviced.

 

[Pokertrampp]

Re: Problematic Johnson 120hp

What are

recirculation check valves.

and where do I find them. My manual does not mention those, is that the same as Reed Valve?

 

[ezeke]

Re: Problematic Johnson 120hp

What are and where do I find them. My manual does not mention those, is that the same as Reed Valve?

Page 2-30 in your factory service manual.