Rough at idle speed

[Woyer]

I have a 1988 23' Sea Ray w/ twin 135 hp.the cowl<br />covers have sea ray(light color) on them but I am told they are mercury's in disguise.<br />I'm having a problem with idle on both,but it is an ittermitten problem and does not happen to both at the same time. <br />They can be idling o.k. one minute,and then it's as if not all cylinder are firing or there is one cylinder that is fowling,then all of a sudden it will rev up like all cylinders are firing again(or the throttle was pushed) and blow out a puff of white smoke,then go back to the bogged effect,this is repeditive, then other times it will idle fine. <br />This seems to be getting worse and more often. <br />If you give it throttle and go back to idle it will run o.k. for a while and then start up again.<br />No problem with missing if motors are taching above 1500rpm But does still happen when idle in gear(slow troll) <br />Have replaced plugs,gas filters,water seperators,and checked for lose or kinked lines.Both motors were gone over by mercury mechanic a couple of season ago and checked out<br />Any Suggestions ??

 

[JB]

Re: Rough at idle speed

Moving to Merc Troubles

 

[KCLOST]

Re: Rough at idle speed

This could be several things....<br /><br />First, does the fuel bulb(s) go flat? Try squeezing the bulb when it misses and see if the motor(s) smooth out.<br /><br />If not, check the firing of the cylinders... This is interesting that it would happen on both motors. So if it's not a fuel issue could be electrical.<br /><br />Try the bulb thing first, keep us informed.

 

[96force 75hp]

Re: Rough at idle speed

Easy G fuel pump needs new diaphram kit!

 

[sprinkler]

Re: Rough at idle speed

I have an 1988 100 hp Mercury. It is designed so that only two cylinders fire during idle. I know that isn't much help, but just wanted to mention it since it may apply to your engine as well. I believe 1988 was the first year for this feature.

 

[Woyer]

Re: Rough at idle speed

Finally got around to starting the motors (88' - 135 merc's )on my Sea Ray.<br />As you suggested, checked to see if the bulbs in the gas lines were staying tight.<br />Sure enough,they are not staying tight with gas .<br />At start up they did sputter and as I would squeeze the ball they would begin to run with a smoother idle ....<br />One of the motors was suppose to have been over hauled before I got the boat.One had a gas leak that was fixed,problem started after first winter I had the boat, about mid summer season.<br />Could a vent Problem have any effect ?<br />Float sticking from bad gas ?<br />Any other suggestions on fix ?

 

[schaiss]

Re: Rough at idle speed

Depending on how your fuel was treated and how well the engine was layed up for winter, pulling the carbs and doing a thorough cleaning always pays for itself in performance. A can of Chem-Dip can be bought at any auto parts store for about $12. Soak metal parts ONLY. If you are careful pulling them from the engine, the gaskets can be reused replacements come in sets and will run about $20. Break down one carb at a time (easier to reassemble a carb when you have one to go by. Idle mix screws should be turned in until seated and then backed out 1 to 1-1/8 turns.