Johnson works on full choke only

[Alberta1]

My old 40 hp johnson (40R 70A) starts and runs nice for a short while only if the choke is kept on full. If the choke is removes, the RPMs drop and the motor dies. Any suggestions would be greatly appreciated.

 

[ob]

Re: Johnson works on full choke only

Look for fuel delivery problem.carb float valves,fuel filters,carb orifices restriction,fuel pump

 

[cannonfodder]

Re: Johnson works on full choke only

Maybe crank seals?

 

[BassMan283]

Re: Johnson works on full choke only

I don't know how comparable they are, but when my '76 6 hp was doing the same thing, a carb rebuild fixed it.

 

[Dank]

Re: Johnson works on full choke only

Had a dirt bike do that once. The carb idle jet was clogged. I had to leave it choked to keep it running at idle 'til I cleaned it out. Could be worth a shot...

 

[Capt. Bob]

Re: Johnson works on full choke only

Probably a blocked passage or jet...carb rebuild.