Evinrude 150 runs rough at low speed

[ncsouthpaw]

I have a 94 150 that will crank and run good for a minute or so then will start to act like it is missing and the longer it runs the worst it gets till it won't run at idle or even low speed. It was doing this the last time I had it out and once I get past the no wake zone and I open it up it seems to run fine. Anybody got any ideas, all help is welcome. I have had this motor about a year and it has always ran like a top. I am not aware of any work being done to it in the past.
Model # E150ELERA
Ser. # G 03522291




Modified by ncsouthpaw at 10:24 PM 5/22/2011

[lamar]

have you changed plugs may have a bad one

[JER-1 BIG BASS]

Plug Gap
BIG BASS

[clm6741]

yea I agree sounds like plugs. good cheap place to start anyway.

[ncsouthpaw]

I haven't changed them, I did pull them out and checked for fouling and did a compression test. They were all burning clean and looked good. The compression was high 100 and lowest 92.

[ChampioNman]

Have you tried hitting the choke and see if it helps? If it does you have a fuel delivery issue if not then it is electrical. Have you checked your head temps?

[ncsouthpaw]

I have dried hitting the choke and sometimes it seems to help but not sure it always does. It smokes a lot at low speeds and seems to be using an excess of oil, I cleaned the fuel filter and disconnected the oil pump and mixed the oil in the fuel tank so that I could elimenate that problem. I have not checked my head temps.

[ncsouthpaw]

Thanks for the help everyone, I changed the plugs this afternoon and while running on the hose here in the yard it seems to be running good. Thanks again.

[ChampioNman]

Champion QL78yc's correct?

[ncsouthpaw]

Auh No, Champion QL77JC4. Thats what was in it, did I do wrong?

[ChampioNman]

Those used to be the original plugs but the chart has been revised to show the preferred plug to be QL78yc. Have you tried adjusting your idle speed jets?

[ncsouthpaw]

No, should I?

[ChampioNman]

If you feel confident in your skills then yes give them a tweak. Need to give them a 1/4-1/2 turn CCW with the motor up to temp and in the water with it running. Wait at least 30 seconds between adjustment.