S.L.O.W. 99 Johnson 25

[MCB]

I have experienced loss of power & rough idle. Can't get up to full RPM. Plugs wet (swapped with extra set, same results), Compression good, fuel OK, Fire to both cylinders. Temp sensor not grounded (closed circuit). Water pump is pissing a good stream. Never had a problem before. What next?

 

[Joe Reeves]

Re: S.L.O.W. 99 Johnson 25

Conrad.... If you have proper compression and spark as you say, I would suspect a clogged/fouled carburetor, especially if the engine's been sitting awhile.<br /><br />However, another cause could be that the fuel pump (if it's equipped with a standard pump) has a ruptured diaphram which would allow excess fuel into the cylinders. Worth looking into.

 

[Offshore Fishing]

Re: S.L.O.W. 99 Johnson 25

I Have had this happen to me on several o.b.s I have owned especially when the engine has not been used for a while..........<br /><br />the easy fix would be replacing the plug wires they get weak, and definitly check ALL your connections coil, and harnesses......<br /><br />If that does not do it, It is probably and most likely the carb(s) (from my past experiences)<br />the carbs needed cleaned (inside), carb kits are cheap, and not that hard to do, pay close attention to the float, valve, needle, and spring.<br /><br />Good luck

 

[Beaux]

Re: S.L.O.W. 99 Johnson 25

My .02 would be toward the carbs.Either need adjustment or most likely clean. Good luck<br /><br />of course, make sure you are using fresh fuel, check you fuel bulb/tank vent/fuel line/pickup tube for restrictions/clogs/ or air leaks as those all can cause rough idleing/loss of power. They are also easy and free to check before getting into rebuilding carbs. Chicken before the egg kind of thing.