1979 johnson 70 hp seahorse

[toneinvic]

can anyone suggest why my outboard boggs-down when I throttle up? If I try to punch it, it just dies. If I give it 1/2 to 2/3 throttle it will chugg along slowly for a while then speed up all by itself. At this point I can give it full throttle and recieve full response. I have cleaned all three carbs and set the float levels. the linkage seems to be OK and the plugs are new. I'm thinking that I may have a fuel delivery problem, possibly a low idle mixture or a plugged fuel filter. additonally, the idle seems to be a little low, it won't idle without giving it a bit of throttle, even when warm.<br />Does anyone have any other suggestions?

 

[Dennis4b]

Re: 1979 johnson 70 hp seahorse

Kinked fuel hose, or bad fuel (i.e. stale, or water in the fuel). If the carbs are fine, that's your best bet (it was for my same vintage Johnson)

 

[toneinvic]

Re: 1979 johnson 70 hp seahorse

Thanks for the reply, but the fuel is new and the fuel line isn't kinked

 

[Joe Reeves]

Re: 1979 johnson 70 hp seahorse

Tone.... I'm assuming that you have good compression, ignition (spark), and that you have not overlooked anything pertaining to the carburetors.<br /><br />That leaves a possible sticking timer base under the flywheel. With the engine off, spin the prop (to line up the dog & gear lobes) and put the engine in forward gear.<br /><br />Now, while watching that timer base, slowly move the throttle to full throttle. That timer base should move smoothly from the idle (retarded) position to the full spark advance position, up against the rubber stop on the end of the full spark advance screw. If that timer base sticks at any point, the engine would be running with the throttles open, but at a retarded timing. Let us know what you find.

 

[toneinvic]

Re: 1979 johnson 70 hp seahorse

Thanks for the new direction Joe, I'll check it this morning and get back to you.

 

[toneinvic]

Re: 1979 johnson 70 hp seahorse

No luck with the timer advance, it's moving smoothly.<br />I haven't checked it yet but would a small tear in the fuel pump diaphram produce the same symptoms?

 

[almost retired again]

Re: 1979 johnson 70 hp seahorse

Hi Tone,<br />I know that you said that you cleaned the carbs, but it sounds to me as though you may have overlooked the low speed and intermediat circuits.Those are the openings behind the throttle plates and the ones just in front of the throttle plates in the throat of the carburator. If these are blocked ,or partionaly blocked it will cause the same problems that you are talking about. Also check the sync and link.<br />More food for thought

 

[Frank Martin]

Re: 1979 johnson 70 hp seahorse

sounds like you need to go over the sink and link adjustments as outlined in the FACTORY sevice manual this sincronizes all three carbs with the ignition system so everything hapens a the rite time critical on all the three cylinder johny/rudes and nesesary every time the carbs are removed

 

[toneinvic]

Re: 1979 johnson 70 hp seahorse

Thank you for all your help, the problem seems to be mostly with the gas tank fitting. The main tank is acting as though there is an air leak. When hooked to my auxillary tank the problem all but dissappears. ****, I thought I checked that earlier! I'm now going to replace all tank and gas line fittings.