Stalling Evinrude 120 at idle when warm

[rustyscrew]

Problem:
Evinrude 120 hp (4cyl) 1994 outboard.
Starts up great.
Runs a bit rough at idle, coughs, but manages when cold.
Runs great at high RPM. Very smooth.
But after its warm, like running for 10-15 minutes at high RPM it won't idle. It starts runs a few seconds, then stalls.

Sounds like a mixture problem to me- confused though because I cleaned all carbs twice, at the beggining of the summer and used it only once since.

History:
It was running rough six months ago, a classic carb job I thought.
I cleaned the carbs, still no improvement, in fact worse.
I discovered no spark on port cylinders. and through this forum figured out the POWERPACK was bad.
I replaced it (from Iboats!) and it worked again.
This was the first run on the new powerpack.
I am guessing this is a different problem related to the carbs.....?

What part of the carb controls low end fuel mixture? I am wondering if it could need an adjustment of the jets. How do I know what position to put them at? (top left screw on each carb- maybe they are out of whack). I don't have the manual for the right year of my engine. The guy that sold it to me told me the wrong year so I have a manual for older evinrudes.

any thoughts- greatly appreciated. Thanks in advance!

 

[tashasdaddy]

Re: Stalling Evinrude 120 at idle when warm

you have no adjustments on those carbs. all fixed jets. suggest spark and compression test when warm. also the "fast start" feature kits out after the engine is warm. you just may need an idle speed adjustment, which must be set after the engine is warm, and in the water.

suggest linc n sinc, and correct manual if you are doing the work.

 

[ezeke]

Re: Stalling Evinrude 120 at idle when warm

Synchronizing the carburetors on the V4 loopers is probably the single most critical step in the tune-up and always needs to be done after servicing the carburetors.

 

[fishcrazy101]

Re: Stalling Evinrude 120 at idle when warm

I have a similar problem with my 150 Johnson. I replaced all the fuel lines and added a fuel filter/water seperatpr and this helped but still have a rough idle at times. Have not found the ultimate cure though yet for the idle. Been told that these motors are sensitive to the type of oil you use so I am experimenting with a change of oil and going to try a seafoam shock soon also. Before I go into the carbs I want to try the easy stuff. I have seen too many other posts that say they rebuilt the carbs and it didnt fix the problem. And the Johnson dealer wants $850 to rebuild them. I will do them myself but still you got 6kits at $20+ and maybe some other stuff once you get in there that isnt in the kit? Do needles come with the kit?

You also may want to check your antisiphon valve at the tank. They can be a source of restriction. I replaced mine with a straight barb as I could not find an antisiphon barb but was advised that I didnt need one if all my fuel line from the tank to the motor was above the fiting.

 

[rustyscrew]

Re: Stalling Evinrude 120 at idle when warm

Do needles come with the kit?

Needles come with the kits. I am guessing it is a link and sync issue. That makes sense since I have cleaned the carbs at least a half dozen times before but I always replaced the same needles and gaskets because they looked good. That always worked really well. This time, one of the gaskets broke, so I was forced to use new kits. This has probably thrown off the synchronization. Makes sense anyway. The carb problem was disguised by the bad powerpack. So maybe a good ole link and sync should do it.

 

[archcycle]

Re: Stalling Evinrude 120 at idle when warm

I had the exact same problem and after half a sync job (waiting on a bolt to unfreeze right now) the problem is almost completely gone. I have a thread out there right now where someone pointed out that my cam follower roller was missing it's opaque rubber sleeve (apparently they crack and fall off) and said it would never sync right without it. Check this too and if it's not there the new roller was only about $10 and has the sleeve on it. Don't forget to buy the rubber retaining ring if you do this