Older johnson 50 hp outboard?

Question

runs bad, idles high then boggs down to almost dead then back high, when you put it in gear then back to idle it revvs up really high for about 30 sec. any ideas?

Answer 1

You need your carbs rebuilt properly then synchronized.

Answer 2

Sounds like a fuel issue. Try fresh fuel & plugs. Check filter(s) Probably going to be a carburator issue

Answer 3

need to know how old is "older"...does it have electronic ignition or points/condenser/distributor?

What's the compression?

problem with running carb cleaner through a two-stroke is, any solvent strong enough to clean the varnish off a carb will clean the lubricating oil right off the cylinder walls.

If you wouldn't run your engine without oil, don't run it on carb cleaner.

Only one way to properly clean a carburetor: remove, disassemble, soak overnight in carb cleaner (I use B-12), blow through passages with compressed air (or aerosol carb cleaner), reassemble with new kits, reinstall, link & sync, adjust slow speed mixture screws (if equipped).

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"electronic ignition late 80s cant check compression no checker"

In that case, do check the timer base, make sure the linkage is in good shape, and that it moves smoothly when you advance the throttle.

Also make sure the throttle plates are parallel throughout their range of motion.

Spark test, get an inline tester (couple bucks at autozone), set the gap for 7/16", clip it to the engine block, attach the plug leads (one at a time), and look for a sharp blue spark while somebody turns the engine over with the key.

If you have good spark on both, and want to skip the compression test (comp. gauge, $25 or so -- no point wasting time & money on a motor with bad compression), then you most likely have an air leak in a gasket...could be a carb mounting gasket, could be intake manifold.

could be something else, but that's most likely.  especially if the fuel line is holding pressure and your fuel is fresh, and no water in the tank.

And assuming compression is good.

In the old days we used to spray WD40 around the intake gasket -- if it leaked RPM's would increase.  But WD40 isn't combustible anymore.  Maybe some gasoline in a spray bottle?

Anyway, were it mine, I'd jump right in to the carb rebuild.  She always seems happier with fresh carbs.  Save the intake for later.

Answer 4

Check and see that the advance under the fly wheel isn't sticking and not closing> It should move free and close when in idle>Run some carb cleaner threw also>