1978 115 johnson Fuel issues.

[lancelotlink]

I have a 78 jonny that drips fuel while it's running, but after i shut it down it just pours out of the butterfly valve.
Seems to run rich at idle, lots of smoke. I have adjusted the floats to try and compensate to little effect.
Almost seems like there's too much fuel pressure. I will do a pressure test this weekend.
Anyone heard of this problem before? I have rebuilt the carbs, I have an original FSM.
Thanks in advance.
I found a prior poster with the same problem, there was no resolution posted.

 

[emdsapmgr]

Re: 1978 115 johnson Fuel issues.

You have not mentioned a carb overhaul with new carb kits. The new kits come with replacement needle and seats. If you've got a leak, could be the needle and seats need replacing. You can purchase the needle and seat individually: current part number 396521

 

[lancelotlink]

Re: 1978 115 johnson Fuel issues.

You have not mentioned a carb overhaul with new carb kits. The new kits come with replacement needle and seats. If you've got a leak, could be the needle and seats need replacing. You can purchase the needle and seat individually: current part number 396521

Thanks for responding. I have rebuilt both carbs with new floats. I think the rebuild was good because the 17 ft runabout was topping out at 46 mph, (GPS).

 

[boobie]

Re: 1978 115 johnson Fuel issues.

You could have a small piece of crap under one of the float needles stuck in the seat.

 

[lancelotlink]

Re: 1978 115 johnson Fuel issues.

You could have a small piece of crap under one of the float needles stuck in the seat.

Yea, thanks. I have already ordered two new rebuild kits. I'm going to start over.

 

[emdsapmgr]

Re: 1978 115 johnson Fuel issues.

A side note: If you are running original fuel hoses from 1978, they are not rated for today's ethanol fuels. Today's fuels will dissolve the hose from the inside. Black bits of fuel hose can migrate down into the needle/seat and the jets. When you have the bowls apart again, looks for any sign of fuel hose deterioration. Those black bits of hose can cram into the wrong places, causing problems.