Rough Idle after each run

1

1marko

Active Member
On a 2016 merc command thrust...500 hours. tuned up at least once a year with fresh plugs
oil and filters...Its like a constant hiccup or miss and smooths out a bit with a little throttle
but appears to be getting worse...I also run fuel stabilizer and jet cleaner regularly .
Question is...do the jets need to be replaced..? There is a water separator i believe.
does this need to be emptied..? Runs like a champ other wise . thx
 
Carbs probably need a good clean. The new gas doesn't keep like it used to, it gums up quickly. Add in our new more efficient carbs with tiny orifices and you are likely to have problems, especially if they don't get a good winterization. I doubt you need new jets, but they probably need to be pulled and cleaned.
That's my bet anyway.
 
My Honda was acting similarly plus was fouling plugs with carbon, sometimes in one outing. I cleaned the carb and didn't see any difference. I also changed the thermostat, but was still fouling plugs. I read somewhere that most kicker motors are optimized for warmer waters than ours. I tried a plug that runs one step hotter and haven't looked back. My understanding is that this would be a bad idea if I was running the motor at high rpm, which I don't.
 
tubber said:
My Honda was acting similarly plus was fouling plugs with carbon, sometimes in one outing. I cleaned the carb and didn't see any difference. I also changed the thermostat, but was still fouling plugs. I read somewhere that most kicker motors are optimized for warmer waters than ours. I tried a plug that runs one step hotter and haven't looked back. My understanding is that this would be a bad idea if I was running the motor at high rpm, which I don't.
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often a missed step when tuning or diagnosing motors.. when racing , I would have several different heat range plugs , and even then , changed jets and or timing to suite the gas , even the weather.. but you do have to be very careful, I nuked a tower of power , when the mechanic put the wrong plugs in .. detonation and led to holed pistons ..( 2 stroke)
definitely take a look at the separator , as a precaution.. but if clogged I'd expect it to be more of a factor when running hard ..
fuel pump? low rpm may not be getting enough pressure, just an idea
 
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Sounds like a similar issue i had which turned out to be the thermostat stuck open. A small twig was sucked up and stuck in the thermostat so the motor ran cold. While at idle speed, it ran rough but at higher rpms the motor wanted the thermostat open so it ran smooth.
 
water pressure..temperature and fuel
flow..all appear to be good... Im leaning no pun intended ...if there
is a water separator that this should be
emptied. ..anyone else do this.?
 
2016 motor with 500 hours. No warranty? Sounds like dirty injectors from poor fuel quality
 
Fox said:
2016 motor with 500 hours. No warranty? Sounds like dirty injectors from poor fuel quality
Click to expand...

Yea and as scott said ...
Not a fan of the mechanic in a can type stuff , but it seems to have a following.. I 'd certainly start at the fuel lines check and or change out your filter system.. supposed to clean ... jets or injectors one or some could be clogged , shouldn't be after mechanic in a can.. if still giving problems , then perhaps a sensor has gone awol .
whichever route you go, you noted it's worsening ..so ..
question: 2 yr old motor , what warranty comes with this?
 
lease return . technically the motor
is three seasons old and warranty
is done. Not a big deal. really happy
so far. just dont want to tear into
something that isnt needed...most do
this is where ive been heading all
along...jets that is...ive run cleaner
that worked for the most part earlier
on but as stated there seams to be a bigger concern t play...and shop time
is off the charts now....thx
 
Water separator is easy, just on the starboard side of the motor is the unit which filters the fuel before its fed to the block. This unit has a drain valve where you can drain out any built up water but it’s rare unless youre running ethanol based fuel or let fuel sit for long periods and not use fuel stabilizers. Theres another smaller plastic filter unit on the port side near to top of the block, which has a small plastic bowl where water can build up or it could get clogged up. It’s a direct replacement for the entire unit cost is like $50 but thats rare as well. I had my thermostats chaged out for $150 at Bridgeview marine. Also check your in fuel filter, its under the water separate unit and a bit difficult to get at but should be checked regularly its like 10-20$.
 
im sorry...no jets.? so how is the fuel
delivered into the intake.?
 
Only air goes through a fuel injected engine's intake. On a turbo engine this air is compressed but in either scenario the fuel is directed under high pressure to each injector located on the cylinder head at the top of each cylinder. The high pressure fuel is developed by the injector pump.
 
Not just a 4 stroke an EFI...lol
So three parts is now my main focus.
what im thinking and or calling jets
should now be referred to as injectors...
there also is at least three or four sensors
for temp...air mass and so on.
still going to look at water seperator.
So by the looks of it the best advice would
probably be a quick diagnostic check
for faults and readings... that should
be under 100 bucks and could save allot of time and mullah. ..BOAT...!
 
Maybe not the right place for this question, but somewhat related.

Anyone use Yamalubes Ring Free product in their fuel? Is this snake oil or does it actually work? I have heard it can really clean out any gummed up residues causing poor performance.

Guessing this wouldn’t help with this issue above but I noticed some seafoam comments and thought I’d ask about ring free. Thx
 
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