1984 johnson 90Hp

[lostfisherman]

I have a "84" 90Hp Johnson that fouls one of the bottom plugs and will not clean out.
VRO is unhooked, gas is mixed 50:1 (well mixed)
carbs have been gone thru
Coil on the cyl. has been replaced
Plugs and wires replaced (Twice)
Comp. is good 125,125,125,130
Still it fouls that one cyl. and runs as a 3 cyl, All the time.
I'm lost !
Any ideas???

 

[tashasdaddy]

Re: 1984 johnson 90Hp

are you using Champion QL77JC4 or QL82C plugs, gapped at .030?

 

[kenmyfam]

Re: 1984 johnson 90Hp

Correct plugs vital. Carbs been rebuilt recently ???

 

[lostfisherman]

Re: 1984 johnson 90Hp

Yep QL28C plugs, But dealer told me to gap them at 32

 

[crxess]

Re: 1984 johnson 90Hp

Check the carb on that cylinder for a loose/damaged/missing orifice plug on that side of the carb. Might be introducing to much fuel.

If possible, swap carb positions and see if the fouling moves to the other cylinder on that side of the carb.

Carb could have an internal crack on orifice passage drawing excess fuel into the cylinder.

 

[kenmyfam]

Re: 1984 johnson 90Hp

Yep QL28C plugs, But dealer told me to gap them at 32

How about the carb's ??

 

[lostfisherman]

Re: 1984 johnson 90Hp

Yep .. Both carbs rebuilt at dealer...

 

[crxess]

Re: 1984 johnson 90Hp

Yep .. Both carbs rebuilt at dealer...

Did this exact condition exist before the rebuilds? If not, there you go.

 

[chubcobear]

Re: 1984 johnson 90Hp

Is it possible the #4 cylinder plug wire is grounding to the hood latch bolt on the port rear side? That happened to me (J90TLCUR). It left the plug clear and wet, not firing.