40 HP Johnson carb problem

[cyberodie]

I have a 1968 40hp Johnson electromatic that hadn't been run for 3-4 years. I bought a carb rebuild kit and rebuilt the carb. When I put gas through it, it ran out the front of the carb. I took the bowl off and checked to see if the needle was still in the seat and if the float was even with the bottom of the carb housing. Everything looked good. I put it back together and still had the same problem. When I first rebuilt the carb, the existing parts looked real good. The boss gasket looked brand new, packing was in good condition, etc. I took it apart again and put the old needle and float in to see if that made any difference. It didn't. I had to take it to a mechanic because it wasn't turning over (bad soleniod). He is working on the carb too and can't figure it out either. He wants to order a new needle, seat and float. Does anyone have any ideas?

Thanks.

 

[BoatBuoy]

Re: 40 HP Johnson carb problem

Did you check the float to make sure it would float? Some older cork floats get their coating compromised by additives in the newer gas and get saturated.

 

[Silvertip]

Re: 40 HP Johnson carb problem

It's very easy to check the operation of the needle and seat before you reassemble the float bowl. Simply invert the carb and blow into the fuel inlet fitting. If you can blow through it you have done something wrong or have used incorrect parts. My guess is that the float is hanging up because of incorrect needle attachment.

 

[cyberodie]

Re: 40 HP Johnson carb problem

The mechanic said he tested it with the bowl off and it seems to work (stop the flow). When he puts the bowl back on is when it doesn't work. I asked if he thought the float was getting hung up in the bowl and he said he thought the same thing but didn't think so when he looks at it.

The carb acted the same with the new float as it does with the old float.

 

[F_R]

Re: 40 HP Johnson carb problem

Bowl vent plugged up? Critters build a nest in the vent?

 

[cyberodie]

Re: 40 HP Johnson carb problem

Thanks for the feedback. Turns out something did build a little nest in the bowl vent. Blew it out and the float shuts off the gas like a champ.

Thanks again.