Rough idle / miss 150hp

[25whaler]

Hello everyone. I have a miss at idle. I have since rebuilt the carbs, the coils are also fairly new and i have decarbed a few times. I still have the miss?? Power pack is only 1 year old. Could it be that a ring is stuck and not allowing fuel to be pulled into the cylinder? all plugs look very similiar. (I just changed pluges tonight as a last resort. I am running champions in it. ALso any recomendations on a diff champion plug these do not have the gap. any suggestions would be greatly appreciated. Thanks

 

[DHPMARINE]

Re: Rough idle / miss 150hp

25whaler,If it runs OK on the new plugs,then goes bad after awhile,switch to gappable ones.If it runs the same when you first start up,I don't think plugs are the problem.<br />Next post tell us more,as to year,model,hours,etc. Fairly new coils can go bad,year old powerpacks go bad quicker.<br />Could even be a loose ground connection.<br />Does your engine have seperate carbs and valve throttle bodies?If so,the idle jets may be in the bodies,and be causing a lean idle.(what it sounds like).<br /><br />DHP

 

[DHPMARINE]

Re: Rough idle / miss 150hp

test

 

[ob]

Re: Rough idle / miss 150hp

Never used a propane torch to locate a lean carb but you could spray some premix into each carb throat with the silencer cover removed and see if the rough idle clears up.Also a compression test would be advisable to determine the health of each cylinder.If that checks out good it's down to ignition or fuel issue.

 

[25whaler]

Re: Rough idle / miss 150hp

DHPMARINE, Thanks for the response. A little more detail. I have a 1986 150 johnson crossflow. New plugs (same result so I dont think the plugs are the problem) Coils are 1 week. Jets were cleaned but not replaced as the oem omc kit only came with float, gaskets and needle valve and seat. Should i rejet? Is there a way to test if which carb is lean? (I have read somewhere on using a propane torch turned on but unlit to find the lean carb) Has anyone used this method?

 

[Dhadley]

Re: Rough idle / miss 150hp

Did you soak the carbs to clean them or just install kits?

 

[25whaler]

Re: Rough idle / miss 150hp

I did not soak completely just in a shallow pan and sprayed with carb cleaner. I let it sit for a few hours and recleaned. The insides showed no sign of dirt or varnish. I did decarb after the rebuild and noticed a pickup in rpm when bottom carb was being sprayed. Does this mean that that carb is running lean?? I was going to take that carb off this morning and go back thru it.