40 hp Johnson starts, but won't stay running

woodieturner

Recruit
Joined
Jan 6, 2012
Messages
4
My 40 hp Johnson was running when i got it, but i didn't run it for a while. I tried to start it but it would not even crank. I tried new gas, 93 oct, no ethanol. I tried to take off carbs and clean them (I really don't know what I'm doing there, but I think i put all the parts back). I finally got the engine to crank with every turn of the key, but it will not run. It starts and it may run for a few seconds, then it dies. Fuel filter cleaned.
Very frustrating. Possibly could have messed something up when I removed the carbs and cleaned them, but it does start and run well...for a few seconds. I can get 20-30 seconds at best.
Any suggestions?
 

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: 40 hp Johnson starts, but won't stay running

What year is the motor?
Will the motor pick up and run if you pump the primer bulb before it dies?
 

Beek14

Petty Officer 1st Class
Joined
Jul 5, 2008
Messages
218
Re: 40 hp Johnson starts, but won't stay running

When you have it running, is it just sitting at idle? Are you trying to give it gas?
 

woodieturner

Recruit
Joined
Jan 6, 2012
Messages
4
Re: 40 hp Johnson starts, but won't stay running

sorry i haven't responded in a quite a while.
I finally took it to a mechanic and he thoroughly cleaned the carbs and put new fuel lines on it. He said that my fuel was bad! Well, the boat ran awesome, but then I couldn't get it started.
Long story short, I finally figure out that to start it I had to measure the fast idle lever. I was just pulling it all the way up. Finally i figured out that I had to find the sweet spot on the fast idle and it cranked right up. Wow, it took me almost a year to figure out how to crank this boat, and I'll probably have to buy a new starter before long with all the superfluous cranking I've been doing.
 
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