Misfire with my Suzuki dt140.

[philtheskipper]

1989 Suzuki DT140<br /><br />I have a misfire at about 1500 rpms. Runs great at any other rpm range. What should I check to fix the misfire? What are the most common causes of a misfire at only a certain rpm range? Will running the engine with the misfire hurt it at all? I try to not run at that rpm, but sometimes it's hard to avoid in the harbor. Any help would greatly be appreciated!

 

[jim dozier]

Re: Misfire with my Suzuki dt140.

Although I suppose its possible to have an ignition problem there I would think its your carbs. 1500 rpms is just above idle so the fuel/air mixture from the carburetor is transferring from the idle circuit to the main jet circuit. Perhaps your idle mixture is a tad on the lean side which makes for a difficult transition to the main circuit. Try enrichening (you are metering air so screw the idle mixture screw in on the Mikuni carbs) your idle mixture 1/8 turn on all carbs and see if it helps.

 

[philtheskipper]

Re: Misfire with my Suzuki dt140.

OK, I'll try that the next time I take the boat out. I forgot to mention that the misfire only happens while in gear, underway.

 

[jim dozier]

Re: Misfire with my Suzuki dt140.

That's probably because the engine is under load. Never evaluate an outboard's performance in neutral. Idle adjustments should be done with the engine warmed up, in the water, and in forward gear. Check your manual but I thinkn the engine should idle at about 700-800 rpms in forward gear.