1970 johnson 20hp only runs for 5 sec.

[Lk40hp]

I recently bought a duck boat motor. It had no spark, so replaced coils plug wires, condensers, etc. Also head where spark plugs go in was cross threaded, was able to thread back onto original threads. NOW only runs for about 5 seconds and quits, just replaced fuel pump, and cleaned carb. It also spits out gas out top side of carb when pullwd over, and ideas?

 

[Daviet]

Re: 1970 johnson 20hp only runs for 5 sec.

If you have gas coming out of the carb, sounds like you still have a carb problem, needle/seat might have a small piece of trash in it holding it open.

 

[Lk40hp]

Re: 1970 johnson 20hp only runs for 5 sec.

That would make sense, had tons of sawdust in carb, even a few small dead bugs, and cloth. Got the motor cheap, but I think it sat for half its life. Seems like right before I bought it someone pulled out a huge mouse nest. I will reclean carb, hopefully that'll help, thanks for the help.

 

[Daviet]

Re: 1970 johnson 20hp only runs for 5 sec.

Make sure and remove the core plug on top of the carb and clean the passages in there if you did not do it the last time you had the carb apart.

 

[Lk40hp]

Re: 1970 johnson 20hp only runs for 5 sec.

Will do, will reply tomorrow and let you know what happened

 

[Lk40hp]

Re: 1970 johnson 20hp only runs for 5 sec.

Cleaned everything, still nothing so took a carb of our one parts motor, now it runs great

 

[Daviet]

Re: 1970 johnson 20hp only runs for 5 sec.

Sounds like there is still an internal problem with the old carb.