'83 Johnson 70 hp runs great with remote primer engaged!

[bautrey]

I'm suddenly having a very strange problem with an otherwise reliable old 1983 Johnson 70 hp outboard. It starts and runs great. Problem is, when I go full throtle it won't produce it's normal power. Very little power in fact. However, if I push in on the ignition key engaging the remote primer - it runs great! In fact, it runs better than ever! Most of the time, if I let off the key, the problem returns and the engine boggs down again. But, sometimes if I hold the key in for awhile, or push it in repeatedly - the problem temporarly goes away. At least for the leg. If I idle down and try to go again the same problem recurs. Anybody have any ideas what my problem could be?<br /><br />Thanks,<br />Bob<br /><br />BTW... This problem started suddenly. It didn't creap up to bad.

 

[Hooty]

Re: '83 Johnson 70 hp runs great with remote primer engaged!

Hey Bob,<br />Welcome to iboats forum.<br />You're down there in ob's part of the country. He'll probably be along in a momento. Your problem is obviously fuel related and could be several things. Could be fuel pump, leaking pulse line to fuel pump, air leak in fuel line, carburator, etc. You can start off by squeezing the priming bulb and see if that has any effect and go from there. Do you have a shop manual for that engine? It'll be a big help.<br /><br />c/6<br /><br />Hooty

 

[Joe Reeves]

Re: '83 Johnson 70 hp runs great with remote primer engaged!

Bob.... When you push in the key, what is actually happening is that fuel is being forced through the primer lines straight to the leaf valves (reed plates) via a passageway in back of the carburetor throttle butterflies.<br /><br />What you are describing would lead me into cleaning and rebuilding the carburetors.

 

[bautrey]

Re: '83 Johnson 70 hp runs great with remote primer engaged!

Hey Guys,<br />Thanks for the quick replys. I had decided that I had a fuel problem, but I never think of the simple things that I could check. I'm always thinking about something more complicated.<br /><br />Joe... I just had the carbs rebuilt late last summer. I think it was in August? Something sticking maybe? Fuel filter maybe?<br /><br />Bob

 

[ob]

Re: '83 Johnson 70 hp runs great with remote primer engaged!

Bob,Hey homeboy, If your motor has sat idle(out of use) for a spell during the winter months it is possible that you have aquired a restriction in one or more of your fixed orifices or ports on carbs.Gummy deposits are quite common .Removal of carbs and clearing of this may be what you'll need to do again.You can help in avoiding this occuring ,if fouled carbs is your problem again,by running your engine on the hose for a few minutes at least once a month or so during the off season.Also adding some Stabil to the fuel tank and running through carbs before storage has helped reduce carb fouling for me.