1974 7.5hp Running on one cylinder

[fshnrod]

Pull trusty 1974 7.5 out of winter storage to fishing, and only runs on one cylinder. Ran perfectly last fall, and winterized properly. Put motor on boat, pumped fuel bulb till hard, choked, 3 pulls and fires right up. Ran a bit rough, didnt think much of it, since it was fogged pretty heavily. Never seemed to "clean out". Took cowl off, top cylinder is cold, bottom is normal temp. Have spark at both plugs, chenged plugs, still no difference. Put a little gas in top hole, and started, no change. Cleaned fuel filter at carb, still no change. Any thoughts? <br /><br />-Fshnrod

 

[Chinewalker]

Re: 1974 7.5hp Running on one cylinder

Hi Fshnrod,<br /> Spark in the open air doesn't mean spark under compression. If you have access to a timing light, see if you've got fire under compression... Could be a coil breaking down. Has the non-firing cylinder popped at all? Has the motor seemed to "kick in" for a second or two? You can try swapping the coils if you determine the plug isn't firing under compression - see if the problem follows the coil...<br />- Scott