1970 60hp Johnson won't run over 2000rpm

OK, bit of a long story but here goes. My 1971 60hp gearbox self destructed last week and I found a 1970 60hp for sale at a reasonable price because it was a non-runner due to the ignition amplifyer being dead. As that part was OK on my engine I bought it and swapped the amplifyer over. The guy I bought it off had done an engine rebuild (new rings, gaskets, etc) and then the amplifyer went and he got chance of another engine cheap so he just put this one at the back of the garage until selling it to me. I was told it had been stood for about 3 years, and it was upright clamped to the end of a bench.

After swapping the amplifyer over and a few odds and ends that were needed I swapped the engine for the one on my boat. I was very pleased when it started up after only a few cranks over. It seemed to run well, so I took it out for a test. Here's where it all went wrong. I pulled away from the jetty fine, just on tickover, but wehen I pushed the throttle forward there was nothing. Then a sudden burts of power (that nearly had me crashing into the jetty!) and I quickly throttled back. But after that nothing on the throttle. It started and idles great, and I can get the revs up to about 2000 on the start throttle, but as soon as I push the throttle forward it just dies.

I'm thinking the idle jets are working fine, but the main jets are stuck/blocked from being stood for so long. Or the floats are stuck and the only fuel getting through is on the idle jet. I'm not very familier with these carbs, as you can probably tell. So my question to the experts is does this sound like what may be happening, and if so what is the easiest solution? If this is load of rubbish, could you tell me what the problem might be?

Thanks
Kevin

Re: 1970 60hp Johnson won't run over 2000rpm

Main jets dirty, you need to piull and phsically clean them wiht a stranded copper wire, just pull back strands till it just fits, run it throught the jet a coupe times and use some Sea Foam.

They are in the bottom of the float bowl behind the drain screw and you will need a long skinny screw driver to get them, use one that just fits in the hole or you may break off the ears on the jet.

There should be 2 more jets also, idle top front and mid back top of carb, clean the also with a wire and Sea Foam and use compressed air to blow out the passages, the air in a can works well if you don't have a compressor.

Do one carb at a time and keep the jets with the cover screws so you don't mix them up and if your gas line is more than 5 years old change it also from the tank to the carbs, it starts to flake off inside and will plug the carb again right away, alos an inline filter is highly reccomended.

Re: 1970 60hp Johnson won't run over 2000rpm

Thanks, sounds like I'm on the right track. I've just looked at the pictures in a manual, looks like I can get to the main jet without taking the carb off the engine. I presume if I take the drain screw out and no fuel drains out then I need to take the carb off and clean the inlet valve as well. Clogged jets sounds likely as the engine stood for a few years, probably with old fuel in it.

Re: 1970 60hp Johnson won't run over 2000rpm

Pull the carbs do em right once not 1/2 way then again cause they are yet problematic.

Re: 1970 60hp Johnson won't run over 2000rpm

OK, so I've just finished srtipping and cleaning all three carbs which should be good, but I'm a little concerned. I didn't find any real problems, none of the jets seemed blocked and it was all fairly clean. It may be that stripping it all down and cleaning with carb cleaner has knocked something out that was causing the problem I won't know until I can try it in water. The only problem was the jet in the centre carb, which was stuck and would not come out -but I cleaned it with carb cleaner and it squirted through Ok, so I think it's alright -just stuck in. If the carbs were alright is there anything else that could cause this problem? Fuel starvation from the fuel pump not getting enough there? I did check the fuel filter which was clean, and all three carbs were full of fuel when I took them off.

Re: 1970 60hp Johnson won't run over 2000rpm

I'm a bit more optimistic now I've run it on muffs, as it revved to nearly 3,000 on the start throttle, which is higher than I got on the water at the weekend on the main throttle. I need to get it in the water and see how it runs, I might ask the local marine shop if I can use their tank -or just go to the boat ramp and run it tied to the jetty.