Hi everyone,
I am a little bit stumped on this one. I recently acquired a 2021 Yamaha F25 (EFI) and have had lots of head scratching ever since. The motor just will not run well in any condition and most notably will not reach full power (maxing out around 4000rpm). Below is a list of symptoms, troubleshooting/items replaced, and a photo with computer data from my motor and a friends same generation F25. I consider myself savvy with engine work but when it comes to interpreting sensor data I admit it's not my forte. If any of you can point me in the right direction I would greatly appreciate it! I know these motors are still relatively 'new' and the support for them just isnt there yet, but this just has to be more simple than I'm thinking at this point.
Symptoms:
*Rough idle. I know these engines idle rough as it is, but this is notably more than other new F25's I have operated
*Sluggish acceleration
*Motor will not reach max spec. RPM between 5k-6k. I can only get it to run around 4000rpm
*Motor will buck and stutter when letting off the throttle, occasional stutter at WOT also
Attempted remdies:
*New fuel, fuel line, separator, bulb, connectors, etc. No change
*Replaced 1st stage fuel filter under cowling, No change
*100 hour service kit with new plugs being the most important - good spark confirmed, no change.
*Injectors removed, cleaned, tested, and re-installed, no change
*New thermostat and tested thermocouple, no change
*Removed and checked LP fuel pump diapragms, all good there
*Removed VST tank and checked HP pump filter, clean. Also checked the additional pre-VST fuel filter, no issues there
Engine data was taken unloaded on a test stand. I know not ideal but hopefully one of you can interpret. After looking at the data, my gut is telling me ISC or TPS sensor issue. I have had the motor at two yamahe dealers and neither of them have taken the deep dive. I can only get "it's just a 25 what do you want me to do?"
Any and all help is appreciated. Thanks in advance.
I am a little bit stumped on this one. I recently acquired a 2021 Yamaha F25 (EFI) and have had lots of head scratching ever since. The motor just will not run well in any condition and most notably will not reach full power (maxing out around 4000rpm). Below is a list of symptoms, troubleshooting/items replaced, and a photo with computer data from my motor and a friends same generation F25. I consider myself savvy with engine work but when it comes to interpreting sensor data I admit it's not my forte. If any of you can point me in the right direction I would greatly appreciate it! I know these motors are still relatively 'new' and the support for them just isnt there yet, but this just has to be more simple than I'm thinking at this point.
Symptoms:
*Rough idle. I know these engines idle rough as it is, but this is notably more than other new F25's I have operated
*Sluggish acceleration
*Motor will not reach max spec. RPM between 5k-6k. I can only get it to run around 4000rpm
*Motor will buck and stutter when letting off the throttle, occasional stutter at WOT also
Attempted remdies:
*New fuel, fuel line, separator, bulb, connectors, etc. No change
*Replaced 1st stage fuel filter under cowling, No change
*100 hour service kit with new plugs being the most important - good spark confirmed, no change.
*Injectors removed, cleaned, tested, and re-installed, no change
*New thermostat and tested thermocouple, no change
*Removed and checked LP fuel pump diapragms, all good there
*Removed VST tank and checked HP pump filter, clean. Also checked the additional pre-VST fuel filter, no issues there
Engine data was taken unloaded on a test stand. I know not ideal but hopefully one of you can interpret. After looking at the data, my gut is telling me ISC or TPS sensor issue. I have had the motor at two yamahe dealers and neither of them have taken the deep dive. I can only get "it's just a 25 what do you want me to do?"
Any and all help is appreciated. Thanks in advance.