One of my F-150's is idling ruff

[TopShot25]

Does anyone have a similar situation that they have overcome and maybe some insight? I?m trying to find out if this is not a big deal or possibly the beginning of a larger problem. I?m hoping somebody can point me in the right direction, with all the new technology I don?t know where to start.

My starboard engine is idling ruff. Does not seem to lack any power and I can?t see any difference at cruise speeds. I pulled the spark plugs and the bottom two, although clean in the middle have a little black around the bottom ring of the plug on the metal threaded part. This is the only difference I can see anywhere as it has always burned cleaner in the past. Actually I?ve been impressed with how clean these engines burn.

Also the engine kind of pops a little now if I raise the idle when I?m flushing it.

I only run Chevron gas in the boat and I have never used any additives.

 

[rodbolt]

Re: One of my F-150's is idling ruff

that pop sounds like a lean out, its a backfire typically in the intake.
its dirt old technology though.
its a simple open loop speed density EFI setup that uses waste spark transistor controled ign system.
time for a leakdown test a good tuneup and cleaning of the fuel system.

 

[TopShot25]

Re: One of my F-150's is idling ruff

Thanks Rodbolt, I've just had such great luck with chevron gas in my cars I guess the injectors are smaller in these outboards and they need more cleaning agents. My engines have ran so great that I guess I got spoiled

This may be old to you as you deal with this stuff all the time. I still like the old days when I could sit on my fender inside the engine compartment of my 76 blazer to adjust the valves.