Some gas in exhaust, an intermittant miss

[nburford]

'95 Johnson 200hp Ocean Runner running not quite right, feels like 5 3/4 cyls. Good compression, recent de-carb, fresh fuel, good OMC oil. Any ideas? <br />Thanks,<br />-Nick

 

[bouner]

Re: Some gas in exhaust, an intermittant miss

running not quite right. Humm<br />Imagine going to the doctor and saying him I'm not feeling quite right. Maybe he will start checking your prostate before knowing you only have a fever. Tell us a bit more. Does it idle fine, what RPM you get at WOT, good spark?

 

[nburford]

Re: Some gas in exhaust, an intermittant miss

OK, it seems to miss a little all the way through the range, from idle to WOT, which currently hits about 5400 rpm. The occaisional faint "pop.......pop..pop" sound can be heard, NOT accompanied by sneezing or any other tell-tales. Starting is a little harder, though it always starts. Spark checked well at mechanics shop, had a coil replaced some time ago. <br />Thanks,<br />-Nick

 

[marinegrh]

Re: Some gas in exhaust, an intermittant miss

maybe start with checking and cleaning the grounds, even though they might look fine, its very problematic when they are corroded, cols,paower pack, etc, look for any loose connections, you carbs .maybe a little piece of trash is floating around, and getting stuck in the jetting or venturi, you didnt mention anything about filter changes, hoses tend to break down with different fuels being run through them, i have also seen high speed nozzles broken or gone causing a hesitation due to to much fuek entering the chambers, pop the air box and look into each carb, like 5 minute check<br />its a start good luck, keep us informed

 

[bouner]

Re: Some gas in exhaust, an intermittant miss

Nick, once upon a time a had a problem similar to yours. In my case i had several things going on wrong in my engine. The first was air leaking in the fuel hoses, this decreased the fuel pressure going into the carbs and made the engine bump at wot. If you have an external in-line crystal fuel filter, do you see air trap there? I also had a couple of rusted grounds and a rusted coil. Since you are getting 5400 RPMs out of your engine, I believe your problem maybe quite simple to solve. You din't mention if you had this problem since you bought your boat, or did it came later.

 

[nburford]

Re: Some gas in exhaust, an intermittant miss

Thanks, guys, a few more details: The problem surfaced around mid season this year, I have had good service for 5 years prior with only routine maintenance. I have a Racor water-seperating filter that I change annually and changed it again when it was acting up without any results. There is no water visible in the fuel, nor any accumulations in the filter. I will look at the grounds and carbs, etc. Thanks again. I need a shop manual, the link in this site seems to only list Clymers, any ideas?<br />-Nick

 

[marinegrh]

Re: Some gas in exhaust, an intermittant miss

Seloc makes a great manual too, your local marine store should have it, if not barnes and nobel or any fine book store<br /><br />good luck, keep us infoed

 

[jim dozier]

Re: Some gas in exhaust, an intermittant miss

Pull the plugs and see if any one looks different than the others. Then pull them 1 at a time (best to ground the loose plug wire) and see if 1 cylinder is the cause of the problem.