One of my F-150's is idling ruff, anyone have any ideas?

[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.

 

[Megabyte]

Do you use any fuel amendments such as RingFree or Star*Tron?
If not, I would start there as it sounds like you have some gunk in your fuel circuit.

FWIW - I use RingFree, Star*Tron, and Stabil at every fill-up (at the maintenance dose).
Motor runs like a Swiss watch.

 

[TopShot25]

No, I have never added anything. I know it’s recommended and that may be the way I have to go, but I have had such great luck with Chevron gas that it’s hard for me to believe I need too. I have never ran anything but Chevron in the boat. The engines have 775 hours on them and I only changed the fuel filter at 500 because I thought I may be pushing my luck and I was upgrading to Racor’s. I just remembered that the engine kind of pops a little now if I raise the idle when I’m flushing it. (I’ll add that to the first post) I really hope it’s just a matter of adding ringfree, I’ve been thinking of that anyway. Does anyone know if there is much difference between injectors of car engines and these outboards? I would guess with the high pressure they are quite a bit smaller, so maybe I really need the ringfree.

I had a GMC mini-van that I put 311,000 miles on before I gave it away, (still running fine) and I never even had to clean the injectors.

 

[Bryan 2530]

Pop sounds like a timing issue, does the 150 have a belt?

I know my 200's have a timing belt and I'm about due for one but they run so nice I am a little hesitant.

 

[FISHON]

John,I have had my single F-150 run a little rough when being returned to 600-700 rpm's just before going into neutral once in neutral it idles fine.It will do it and almost sound like its stumbling and ready to fall on its face,but never stalls and no indication on the tach of fluctuating rpm's,kick it up alittle to 800 and it stops or drop it into neutral and it stops and runs great.. This only happens every now and then,very inconsistently.Had a yamaha mechanic look at it and said it runs fine.Ran perfect all summer untill two days ago when looking for a sculpin spot as slow as possible in gear (600-700) it did it again.I always run chevron 92 and ring free every time and all maint. done stricty on time,the engine only has 275 hours.This all started last year,maybe I should change the 10 micron filter more often,every 50 hours instead of a 100.Plugs are all good ,and runs great at all other rpm ranges , no problems other than this the yami has been great.I'll let you know if I find something that works.I plan on changing the 10 micron and dumping it in to a glass jar to see if there is any water. Sorry if I rambled but this bugs me.I know you want this handled before bug season.

 

[TopShot25]

Thanks guys for the info. It sounds like I need to clean the injectors and see if that helps. If that helps I guess I will need to start using ringfree. Time will tell.

 

[Luv2fish]

Fishon,
I also have the F150 and noticed the running rough about 600-800 RPM when coming of plane. If I go directly to neutral and then back in gear it seems to disappear. I think it might be the back pressure on the prop (if possible) when the boat is going faster than the prop. If I wait for the boat to slow down it stops.

I've also seen others mention this problem but never a solution.

Steve

 

[tara11]

I use that Chevron fuel additive, it is cheapest at Pep Boys, my mechanic friends swear by it !

 

[Laura Lee]

Spoke to a mechanic the other day and he said the yamaha 150 as you get to idle rpm's will electronically run on 4 cylinders instead of 6. He said that they will often run alittle rough at idle. I have twin 150's and have not noticed this as of yet. What you discribe sounds like what he may have been suggesting.