Sputtering Motor

[bsnyder]

Hi all, I have a 2000 15hp Tohatsu outboard that has developed a sputtering problem. During the first 5-10 min, the motor seems to be running on one cylinder and won't accelerate beyond 2000 rpm or so in gear (some backfiring at idle too). After running at WOT for the 5-10 minutes, the motor gradually stops sputtering and runs normally. I've checked the plugs and they appear fine...gap ok too. I'm guessing this is a timing issue?? Any suggestions? Thanks in advance

 

[JB]

Re: Sputtering Motor

Hi, BSnyder. One carb or two??<br /><br />Standing by,<br />JB

 

[bsnyder]

Re: Sputtering Motor

Hi JB, the motor has one carb and has about 35-40 hours on it...bought it new last year. The symptoms are now occuring somewhat even when the motor has been running 20 minutes. It also backfires through the exhaust when cold and at idle. I'm surprised with this problem since the motor is new and I've always used good gas and Quicksilver 2-cycle oil. Well, I can't think of any other symptoms to tell you so thanks for your help.

 

[Liam]

Re: Sputtering Motor

Sounds like a flooding problem. How's the choke?<br /><br />Liam

 

[bsnyder]

Re: Sputtering Motor

Hi Liam, the choke seems to be functioning properly and has never been tampered with so it should still be set properly. As I mentioned in my first post, I'm wondering if the timing could have drifted in the 40 hours of use...based primarily on the backfiring through exhaust at idle. I'm experienced with auto engine repair but new to 2-cycle outboards. Thanks for your reply.

 

[bsnyder]

Re: Sputtering Motor

Hey JB, and others - any more thoughts on my sputtering problem

 

[JB]

Re: Sputtering Motor

Howdy, BSnyder. While I was rereading the thread just now I was trying to turn your terminology into sounds I am familiar with and I come up with what we used to call "four cycling" for your "sputtering", and "coughing" for your "backfire".<br /><br />Coughing usually occurs during start and warmup when the engine is very lean for its needs. It goes POOOF!! and jerks. Choking stops that.<br /><br />Four cycling is the engine running so rich at medium and higher speeds that it only fires on alternate compression strokes. The result is a pretty large power loss and extra smoke. I haven't heard an outboard four cycling in years. It is possible, if your carb has the float too high it could be flooding the engine just enough to cause trouble at first, then the engine catches up with the fuel pump and there is no longer a surplus of fuel. That of course, doesn't explain the symptoms of running lean at idle and during warm-up.<br /><br />I'm pretty sure your problem is fuel related.<br /><br />If both your low and hi speed jets are adjustable, back the low out about 1/4 turn and turn the hi in about 1/4 turn. Recheck your float setting.<br /><br />Red sky at night. . .<br />JB

 

[bsnyder]

Re: Sputtering Motor

Thanks JB...your description matches what I'm seeing exactly. I'll give your suggestions a try. Thanks again.