on to the next problem with my 1965 johnson 40hp

I've finaly figured out the spark problem and have strong spark at both cylinders now. Tested everything in my driveway before I took it to the lake, staetrted perfect and reved up just like it should. Got around to taking it to the lake a couple days ago and for the first 30 seconds everything was going great. Started fine at the dock pulled out and started to open her up half throttle( engine was purring like a kitten) then got out a little ways and it started to sputter and eventually died. Got it to start again but would only run at quarter throttle and barley move maybe 2mph max. Checked it out again in the driveway and same thing even with no load it wont rev past quarter throttle. Still starts fine and idles ok but does this thing where it has a backfire hiccup every couple seconds. Does this sound like a bad float adjustment or more of an electrical issue. I also talked to a guy at my work and he says it could be an air leak??

Re: on to the next problem with my 1965 johnson 40hp

Sounds like you dropped a cylinder again. Recheck your spark.

Re: on to the next problem with my 1965 johnson 40hp

I have checked spark with both plugs out and it is seems to have strong spark on both(I do have to brand new coils waiting to install if needed). Does a hiccup mean that it is running lean?

Re: on to the next problem with my 1965 johnson 40hp

When is the last time you cleaned/rebuilt your carbs. Sounds like it is time You may have a high speed jet clogged, stuck float, old gas goo etc... They are pretty simple to do and it will probably solve your problem. Make sure that you soak them in a good carb cleaner, preferably overnight, and blow every hole out with compressed air.

Re: on to the next problem with my 1965 johnson 40hp

yea when i bought the boat i had to get a float and did a little cleaning with the aircompresser while it was on the boat. Can i run a fuel filter on any of these lines before or after fuel pump?

Re: on to the next problem with my 1965 johnson 40hp

clean carbs a lot better than compressed air just like fireman57 soak it really well then poke a wire or something that will fit in the jets and loosen the crud that way then soak it and then use compressed air. it does sound like the high speed jet is still clogged

Re: on to the next problem with my 1965 johnson 40hp

got around to cleanin the carb called my local johnson shop and he told me there was a high speed jet behind the drain screw. Took it out and what do ya know, completely cloged! Blew it out with some compressed air and bamm runs like a champ... for a bit. Now it keeps stalling out, but if i keep pumping the hand bulb it stays running. I did take the fuel pump apart at a earlyer time to make sure that was clean and im may have put it together wrong? Does anybody know where i can maybe get a new one or how they are supposed to go back together? From looking on the internet at stock ones it deffently looks different (it is square in shape).