RPMs on starboard motor unstable

[Daniel Rogers]

I have a 2018 AR210 which recently had some work done on the starboard bearings and pump, both were replaced due to water getting into the bering. First outing on the water after the repairs I had to jump the boat to get it to start, no further battery issues, voltage showing just under 12v. After getting it started the starboard engine RPMs started fluctuating at idle almost like it was going to die but didn’t. Then under power it will pause for a Split second at 4K RPMs then jump to 6k RPMs. Any ideas or suggestions on what could cause this? Could there be a battery issue affecting just 1 motor?

uploaded a video of the RPMs while at idle

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[Ronnie]

I’d start by replacing the spark plugs. If that doesn’t fix it, move coils form the smooth running engine to the other engine. Lastly switch out the eCms. It’s all process of elimination with the low dollar items being first. Spark plugs under $10 each, coils $250 each, Ecms run about $1,200.

 

[Daniel Rogers]

I’d start by replacing the spark plugs. If that doesn’t fix it, move coils form the smooth running engine to the other engine. Lastly switch out the eCms. It’s all process of elimination with the low dollar items being first. Spark plugs under $10 each, coils $250 each, Ecms run about $1,200.

Thanks Ronnie, its still under warranty, got the extended one. I may end up taking it back to Yamaha for them to diagnose and fix.

 

[Ronnie]

I would call them first. If they say it will be two to four weeks before they can check it out, you may want to do the trouble shooting yourself rather than lose a chunk of the season to a shop.

 

[zipper]

I have a 2018 AR210 which recently had some work done on the starboard bearings and pump, both were replaced due to water getting into the bering. First outing on the water after the repairs I had to jump the boat to get it to start, no further battery issues, voltage showing just under 12v. After getting it started the starboard engine RPMs started fluctuating at idle almost like it was going to die but didn’t. Then under power it will pause for a Split second at 4K RPMs then jump to 6k RPMs. Any ideas or suggestions on what could cause this? Could there be a battery issue affecting just 1 motor?

uploaded a video of the RPMs while at idle

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Less than 12vdc is a weak battery. Here is a typical battery state of charge chart.
I would check the battery and spark plugs and make sure who ever did the work, reconnected all the battery wiring correctly, if it was disconnected.



Edit: Was your reading of less than 12v at rest, or after starting? Did you monitor the voltage after starting while the “fluctuation” was happening?

 

[FSH 210 Sport]

I have a 2018 AR210 which recently had some work done on the starboard bearings and pump, both were replaced due to water getting into the bering. First outing on the water after the repairs I had to jump the boat to get it to start, no further battery issues, voltage showing just under 12v. After getting it started the starboard engine RPMs started fluctuating at idle almost like it was going to die but didn’t. Then under power it will pause for a Split second at 4K RPMs then jump to 6k RPMs. Any ideas or suggestions on what could cause this? Could there be a battery issue affecting just 1 motor?

uploaded a video of the RPMs while at idle

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When you say that you had to jump it to get it started, was there enough battery to at least turn the motor over slowly a few times? or was it like it was dead and all you got was a click? Did you use a jump pack, or an emergency paralleling switch?

You’ll need to charge the battery(ies) up properly after that depth of discharge using a proper charger, the boats charging system won’t do it properly.

Ive read several threads where a bad battery was causing the engine to run peculiarly if not bad, not sure if that’s limited to the E series boats or not.

Was the port engine running normally? How long did you run the boat on the first time out? did the starboard engine improve or did it run that way the whole time you were on the water?

 

[Daniel Rogers]

Less than 12vdc is a weak battery. Here is a typical battery state of charge chart.
I would check the battery and spark plugs and make sure who ever did the work, reconnected all the battery wiring correctly, if it was disconnected.

View attachment 179364

Edit: Was your reading of less than 12v at rest, or after starting? Did you monitor the voltage after starting while the “fluctuation” was happening?

I ran it for about 20 mins after jumping with a small jump box, then had it on a trickle charger overnight. At rest I’m reading just under 12v, when I’m in running mode I can’t get voltage readings on the dash. This is the original battery for the boat so I think my first step is new battery, never know if that could cause it.

 

[Daniel Rogers]

When you say that you had to jump it to get it started, was there enough battery to at least turn the motor over slowly a few times? or was it like it was dead and all you got was a click? Did you use a jump pack, or an emergency paralleling switch?

You’ll need to charge the battery(ies) up properly after that depth of discharge using a proper charger, the boats charging system won’t do it properly.

Ive read several threads where a bad battery was causing the engine to run peculiarly if not bad, not sure if that’s limited to the E series boats or not.

Was the port engine running normally? How long did you run the boat on the first time out? did the starboard engine improve or did it run that way the whole time you were on the water?

it was kind of odd, got the motors started, then they died and I couldn’t restart. I used a small jump box the marina had to get it started back up. After that only the starboard engine was fluctuating, the port engine is fine. Starboard engine seemed to run like that only at idle/in neutral. I’m thinking I’ll just replace this battery and check all the cables.

I did put the battery on a trickle charger overnight but still showing under 12v on the dash before startup.

 

[FSH 210 Sport]

it was kind of odd, got the motors started, then they died and I couldn’t restart. I used a small jump box the marina had to get it started back up. After that only the starboard engine was fluctuating, the port engine is fine. Starboard engine seemed to run like that only at idle/in neutral. I’m thinking I’ll just replace this battery and check all the cables.

I did put the battery on a trickle charger overnight but still showing under 12v on the dash before startup.

Replacing the battery sounds like a solid plan….be sure and check all the grounds and connections from the engines as well. If you are still running the batteries that came with the boat there’s a good chance they need replacing, especially if you do not have an onboard charger that is used after each outing and while the boat is being stored.

Trickle chargers do not have the ability to properly charge a battery after it has been heavily discharged, you need a quality smart charger like a NOCO or MinnKota 10A charger. The charger needs to have a manual equalizing charge function that can be run once a month. When running flooded lead acid batteries a hydrometer should be used to check the specific gravity to make sure all the cells are balanced.

There is no reason the shop that did the repairs should have messed with the batteries while completing the work you stated above.

 

[Daniel Rogers]

Battery replaced this weekend, no change in starboard engine behavior at idle. I’m not losing power when on the water got it up to 47mph and sounded great. Going to swap spark plugs out next weekend.

anyone have recommendations on what plugs to use for a 2018 AR210 with the TR-1 motors?

 

[FSH 210 Sport]

Battery replaced this weekend, no change in starboard engine behavior at idle. I’m not losing power when on the water got it up to 47mph and sounded great. Going to swap spark plugs out next weekend.

anyone have recommendations on what plugs to use for a 2018 AR210 with the TR-1 motors?

The stock ones.

 

[Daniel Rogers]

I forgot I took a video of the engine itself at idle last weekend.

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[212s]

I forgot I took a video of the engine itself at idle last weekend.

If it still has the stock plugs, it could be missing causing the rough idle. How many hours are on the plugs/engines?

 

[FSH 210 Sport]

After watching that video it makes me think there is a sensor problem. I’d check the hose that goes to the MAP sensor to make sure there is not a crack or leak and or that the line is not contaminated with a substance. Also check the wiring to that sensor. Also check the wiring / connections on the cam / crankshaft position sensor as well as the intake air temperature sensor.

Did you change the spark plugs? What did the ones look like that came out of the affected engine?

 

[Daniel Rogers]

Final update: I changed the original spark plugs out today (180 hours on them) and she is running like a dream! From now on that’s an annual maintenance item for me, so easy!

Pic of the old plugs.

Thanks everyone!!!

 

[FSH 210 Sport]

I’m stoked to see it was a simple plug change that solved your rough running engine problem!

The old plugs despite not working good at idle all look consistent with roughly 5 threads of heat on them.

Thanks for following up and closing the loop!