1984 Johnson 30HP dies after 10 minutes

[sdreffs]

I finally got my boat on the water today and while running WOT for about 10 minutes the motor bogs and dies like it is running out of gas. After it sits for about 5 minutes it will run good again for 10-15 minutes then die again. The water pump is working good and the motor is warm but not hot (can touch with hand). The gas is a little old but not much more than 6 months.
Could this possibly be the carburetor?
Thanks!

 

[Mas]

Re: 1984 Johnson 30HP dies after 10 minutes

Start with fresh gas!

Seems like possibly some dirt is clogging the fuel passages...then settling when it dies...then repeats. Check the fuel pump screen.

Also, as the motor begins to die, pump the fuel line bulb and see if the motor picks up.

Finally, if none of these help, pull the plugs and examine...look for very wet plugs...or even possibly small beads of water.

Have you checked compression? Quality of spark?

Mas

 

[sdreffs]

Re: 1984 Johnson 30HP dies after 10 minutes

I will put new gas in this weekend. I did check compression when I bought the boat and it was good on both cylinders and within 2 psi from each other.

How do I check quality of spark?

 

[jonesg]

Re: 1984 Johnson 30HP dies after 10 minutes

Open the tank vent.