90 hp evinrude running rough/stalling

[jerb_54729]

My 1988 90 hp evinrude vro will start fine, but will spit and sputter and stall if I try to give it gas. If I push the choke in it helps a little, but still runs rough. When I finally coax it up to planing speed, it will run great. If I run at WOT for 10 minutes or so, I can pull the throttle back to neutral and get it back on plane with no problems/pull water skiiers, etc.<br />However, if I shut it off for 10 minutes and restart it does the same thing.<br />I have replaced the spark plugs, fuel line/primer bulb, cleaned pickup, checked fuel tank vent.<br />Where do I go from here?

 

[jimdi@localnet.com]

Re: 90 hp evinrude running rough/stalling

It sounds like a idle mixture problem to me. When you push in the choke - you are riching up the mixture - when leads me to believe that you are running lean. When an engine comes off WOT it will run for a while a little lean.<br /><br />Get this checked - get a manual on your engine. I could give you the procedure for a force and for an old Johnson - but it might be different for yours - <br /><br />A too lean mixture will cause overheating - and wear.<br /><br />(the procedure for mixture for mine is - at idle (start with screws 1.5 turns out from seated) with water running through - turn mixture screw in - until rpms drop (too lean) - then slowly turn out until rpms drop (too rich) set at midway point between 2. Do same for multiple carbs - and average setting between carbs - set all carbs to this "average" setting.

 

[jerb_54729]

Re: 90 hp evinrude running rough/stalling

I have run SeaFoam thru the gas several times a year since I've owned it, but do you think my carb could be gunked up and causing it to run lean?

 

[Greg Lawrence]

Re: 90 hp evinrude running rough/stalling

thats a good possibility, mine was bogging and i could push the choke and it would fly, took apart my carbs, found a bunch of broke loose gum floating in there. will get to run it tommorrow.

 

[jerb_54729]

Re: 90 hp evinrude running rough/stalling

Problem finally gone!! I replaced the entire fuel line, removed the anti-siphon check valve on the fuel tank, and de-gunked with OMC Motor Tuneup. Motor spit smoke and oozed black stuff out through the exhaust. I let it sit for 6 hours, then ran at high speed for 1/2 hour. Motor runs great now!