1985 Johnson gt 150 troubles

[beardog1234]

Motor runs fine on muff revs fine but when drop in the water it just bogs down and won't rev over 1200 carbs have been rebuilt new power packs new plugs all new fuel lines from tank to carb s every oil and fuel line has new clamps new primer bulbs any thing I may have overlooked

 

[SigSaurP229]

Re: 1985 Johnson gt 150 troubles

What are the compression numbers on it?

 

[beardog1234]

Re: 1985 Johnson gt 150 troubles

Haven't ran them yet but whats different that if you let it idle for a bit it will eventually take off and run fine till you start it up again after cooling off

 

[SigSaurP229]

Re: 1985 Johnson gt 150 troubles

I would run a compression check on it first, I would follow immediatly with a spark test.

Also take a look and make sure that the timer advance arm is moving.

 

[SigSaurP229]

Re: 1985 Johnson gt 150 troubles

Some motors with low compression numbers will run fine until you put them in the water under a load.

 

[Watermann]

Re: 1985 Johnson gt 150 troubles

Did you replace the fuel pump too or rebuild it? Sounds like it could be starving for fuel due to broken or most likely an old stiff diaphragm and or a plugged diaphragm vacuum hole. Do you have to keep nursing it along until finally it will get up and go after embarrassing the heck out of you?

 

[emdsapmgr]

Re: 1985 Johnson gt 150 troubles

Check all 6 cyls for spark after the engine is warmed up to normal operating temps. That engine will sound just fine, running on the trailer with 4 or 5 cyls firing.

 

[beardog1234]

Re: 1985 Johnson gt 150 troubles

Did you replace the fuel pump too or rebuild it? Sounds like it could be starving for fuel due to broken or most likely an old stiff diaphragm and or a plugged diaphragm vacuum hole. Do you have to keep nursing it along until finally it will get up and go after embarrassing the heck out of you?

Yes that's exactly what its doing

 

[Watermann]

Re: 1985 Johnson gt 150 troubles

Only thing left in your fuel system not rebuilt or replaced would be the fuel pump and that is exactly what my Johnny would do before I rebuilt my fuel pump.