Low RPMs

[Fausto Trujillo]

Hello
Please help.
I recently bought a used 2011 Yamaha AR210 , both engines with around 240 hours .
The starboard engine is running at 7000 RPMs at full throttle while the port one runs at 8500 up to 8800 RPMs at full throttle. I want to get the stb engine up to at least 8500 RPMs.
Things I have done so far:
1- I swapped fuel pumps: I connected the port one to the starboard engine and stb to port, that did not make any difference on RPMs
2- compression test: all cylinders around 140 PSI no mayor differences amongst them. I will get back with precise numbers.
3- I bought 4 not OEM coils and installed them, that did not make any difference on RPMs.
4- Bought and mounted 4 refurbished OEM injectors and that made a difference of about 500 rpms, the engine went to 7500 rpms.
5- I did put new air filters just in case.
6- New engine oil and filter, made sure it is not overfilled.
7- I swapped ECMs: port to starboard and stb to port. That did make a difference but not the one I was looking for. I Gained around 300 RPMs on the port motor and lost 200 on the stb one, this is how now my port engine goes up to 8800 from 8500 before and the stb one went from 7500 to around 7300.
8- I have checked my throttle cables and made sure that they are pulling the accelerator position sensor (APS) is going all the way to the stopper at full throttle
-9 New spark plugs, did not make any difference. I noticed that the sparkplugs from both engines were black in color like if the engines were getting too much fuel or fuel rich.
I don’t know what else to do , please any help will be greatly appreciated.

 

[anmut]

How old is your gas?

 

[Acard7]

Pull your starboard pump and make sure there’s nothing hindering the impeller and shaft. Inspect the impeller for damage. Not that this should make for lost RPM issues…

Inspect all connections to the coil packs. If you have YDS software you can do some more diagnostic testing, unless you’ve already tried that?

Definitely a puzzling issue you’re having.

 

[Fausto Trujillo]

How old is your gas?

90% a week old the rest a month may be

 

[Fausto Trujillo]

Pull your starboard pump and make sure there’s nothing hindering the impeller and shaft. Inspect the impeller for damage. Not that this should make for lost RPM issues…

Inspect all connections to the coil packs. If you have YDS software you can do some more diagnostic testing, unless you’ve already tried that?

Definitely a puzzling issue you’re having.

I forgot to mention that I also swapped the jet pumps, port to stb and viceversa. I inspected them too, all was clean, wear ring, impellers, all good. Yes I have YDS software but have not done any tests yet. What do you recommend please?

 

[Acard7]

I forgot to mention that I also swapped the jet pumps, port to stb and viceversa. I inspected them too, all was clean, wear ring, impellers, all good. Yes I have YDS software but have not done any tests yet. What do you recommend please?

I honestly haven't had to run the tests myself, hopefully others have chimed in here. But you should be able to test each coil pack for spark and injectors as well in the diagnostic portion of the software if you look around in it.

Below is a link to a manual that's not confirmed but seems to be a good resource:
YDS manual

 

[Neutron]

Hello
Please help.
I recently bought a used 2011 Yamaha AR210 , both engines with around 240 hours .
The starboard engine is running at 7000 RPMs at full throttle while the port one runs at 8500 up to 8800 RPMs at full throttle. I want to get the stb engine up to at least 8500 RPMs.
Things I have done so far:
1- I swapped fuel pumps: I connected the port one to the starboard engine and stb to port, that did not make any difference on RPMs
2- compression test: all cylinders around 140 PSI no mayor differences amongst them. I will get back with precise numbers.
3- I bought 4 not OEM coils and installed them, that did not make any difference on RPMs.
4- Bought and mounted 4 refurbished OEM injectors and that made a difference of about 500 rpms, the engine went to 7500 rpms.
5- I did put new air filters just in case.
6- New engine oil and filter, made sure it is not overfilled.
7- I swapped ECMs: port to starboard and stb to port. That did make a difference but not the one I was looking for. I Gained around 300 RPMs on the port motor and lost 200 on the stb one, this is how now my port engine goes up to 8800 from 8500 before and the stb one went from 7500 to around 7300.
8- I have checked my throttle cables and made sure that they are pulling the accelerator position sensor (APS) is going all the way to the stopper at full throttle
-9 New spark plugs, did not make any difference. I noticed that the sparkplugs from both engines were black in color like if the engines were getting too much fuel or fuel rich.
I don’t know what else to do , please any help will be greatly appreciated.

Are you getting 140psi compression reading from both engines or did you just test the low rpm engine. 140psi on a non supercharged or turbo 4 stroke is very low from my experience. Should be 170+

 

[anmut]

Are you getting 140psi compression reading from both engines or did you just test the low rpm engine. 140psi on a non supercharged or turbo 4 stroke is very low from my experience. Should be 170+

Cold or hot compression should be 170?

 

[Neutron]

Cold or hot compression should be 170?

Cold with throttles open. Most heathy NA 4 strokes are closer to 190psi
2 strokes are 125 to 150 psi