power loss, noises from 4 hp Johnson '93

I have two symptoms/problems but they may be related.<br />My 4 hp johnson I bought new in '93. it has run (saltwater) great since with only plugs replaced. <br />This year I have noticed a significant loss of power. Previously it could get my 11 ' inflatable up on a plane with myself and my 70 lb boy. Now I can't get it on plane with just myself. It starts well. It has electronic ignition. Sould I do some sort of tune up or is ther something else i should do? I have used several tanks of gas it hasn't changed. except for the problem below it runs smoothly at all rpms.<br /><br /><br />Question two: <br /><br />I have just started feeling a series of sharp "taps" occasionally when running at 1/2 or greater throttle. It doesn't feel like a vibration but more like the drive train has been tapped with a hammer. or that suddenly there is a disconnect within the drive train and then the tap occurs when the connection is made. <br />This noise/tap is intermittent. <br /><br />Any ideas about what to look for would be great.<br /><br />thanks,<br /><br />Mike.

Re: power loss, noises from 4 hp Johnson '93

Hi, Mike.<br /><br />First. After 11 years you are sure to need a new impeller in the water pump.<br /><br />I suspect that the tap you hear is an engine misfire. It could be carb mixture related.<br /><br />I think it is time to decarb; then overhaul your carb and do a fresh link 'n' synch.<br /><br />Good luck, and let us know the outcome.

Re: power loss, noises from 4 hp Johnson '93

"I think it is time to decarb; then overhaul your carb and do a fresh link 'n' synch."<br /><br />to translate I think you said :<br />1. de carbon the engine <br />2. rebuild the carbourator <br /><br />3 Fresh link'n synch ???????<br /><br />thanks,<br />m

Re: power loss, noises from 4 hp Johnson '93

Linkage and synchronization adjustment, Mike.<br /><br />Adjusts throttle linkage and synchronizes it with the ignition timing.<br /><br />Sorry for the jargon.

Re: power loss, noises from 4 hp Johnson '93

Another idea is that it may be over-heating.<br />Was the motor winterized and flushed(fresh water) prior to storage?Like JB said,maybe suspect a water pump failure.The noise you hear could also be piston slap if its over-heating enough.Make sure its pumping sufficent water and the gas/oil mix is 50:1.