97' Johnson 9.9 acting strange

Hello everyone, I just bought a 97' Johnson 9.9 that was used as a backup motor in saltwater. Took it out today on my 10' Avon Inflatable and it ran perfect for about 10-20 minutes, then stopped. Tried to restart it and would only start with the choke pulled out, then if I pushed it back in and gave it throttle, it died. If I left it with the choke out it would run up to about 10% power. Turned it off for about 30 minutes and it started running like new again for about 20 minutes, and then the same problem. Could it be that the thermostat closes the fuel flow into the engine if it's overheating? Didn't seem too hot to me. I'll order a new water pump kit and try that. Is there anything that indicates if water pump is working fine in these engines? By the way, in all this time, the motor always started on 1st pull.<br />Thanks in advance for any help!

Re: 97' Johnson 9.9 acting strange

What it sounds like is you need a carb cleaning....right off. Is the fuel tank venting? If the fuel tank is not venting, you can draw a vacuum on the tank and fuel will not flow to the fuel pump. Crack the gas cap and see if that makes a difference. <br /><br />Next see if squeezing the primer bulb keeps it running. If not, take some premix fuel in a spray bottle and when the engine starts to die, shoot some premix into the carb throat. If it keeps running, likely the carb is gunked up inside and needs cleaning.<br /><br />If squeezing the primer bulb keeps it running, might be the fuel pump has gone south.<br /><br />Is the fuel line to the tank in good shape?

Re: 97' Johnson 9.9 acting strange

The fuel tank is venting, it has the little vent over the gas cap and I had it open. The fuel line to the tank is in perfect shape. I don't know if it might be the fuel pump because I ran it in idle with the choke pulled out for like an hour and it didn't turn off. And the carb seemed very clean when it was running fine. I guess what I'm also trying to ask is if there's like a fuel cutoff swith that doesn't let you run the engine at high RPM when it gets overheated?

Re: 97' Johnson 9.9 acting strange

First off is it a 2 stroke or 4? <br /><br />Have you checked the spark plugs to see if one is fouled more than the other? You would be amazed at how well these motors run on one cylinder until a load is put on it. <br /><br />Another thing if you are convinced the fuel supply is OK, there may be a loose electical connection, OR a coil or power pack getting weak & after it warms up it will cut out. Let it cool & it will run again until it warms up.

Re: 97' Johnson 9.9 acting strange

Thanks for the replies guys, the engine is a 2-stroke, both spark plugs look good and there seems to be no loose electrical connections on the engine. I don't think it's running on 1 cylinder because at first it get the boat to ~20 mph with 3 people on it (about 170# each), and then when it acted up, it would not push it past 5 mph with only me one it, and the choke full out. Another thing was that if push and pulled the choke continuosly when running, it would accelerate a little more. I guess it could be the power pack warming up and cutting out or something of the like, how would I test it?

Re: 97' Johnson 9.9 acting strange

Just out of curiosity, if the water pump isn't pumping too well, and the engine gets a little warmer than it should, could that cause the powerpack to overheat and weaken until it cools down again?

Re: 97' Johnson 9.9 acting strange

Don't think it's the power pack Passat. From your post's, it does sound like something in the carb float bowl. Idling or running with the choke out should kill the engine because of too much fuel. If it idles with the choke out and picks up when the choke is pulled out and then in, really points to the carb being fouled. I think, and this only thinking, I would pull the carb and give it a good cleaning out.

Re: 97' Johnson 9.9 acting strange

Thanks for all the advice, I'll clean out the carb in a few days and see if that does it. I'll post the result of it when I do so. Any extra input is welcome. <br />Thanks again!