constantly varying RPMs

[PNW Islander]

I’ve got a 2018 Honda 250 with 300 hours on my 22’ Bullfrog Ranger. The RPMs constantly surge and decrease up and down by approximately 75-150 RPM. Sometimes the difference is greater and the RPMs will vary by about 350- 500 RPM - enough that passengers will need to gain their balance when the boat slows. It happens at all speeds but seems to be most prevalent in the midrange between 3500 - 5000 RPMs. On two occasions when the motor was freshly started it was varying by 300-500 and actually caused the motor to stall and alarm. Unfortunately I did not notice at the time what light came on with the alarm and I could not get the boat to service center with computer to check the alarm code before the computer reset.

I’ve gone though motor and had local service center look at it and they could not find the issue but filters, oil, compression, etc. seemed fine.

I would seriously appreciate any advice out there as this is frustrating at best.

thank you!

 

[racerone]

Test run with a 5 gallon tank and new hose.

 

[PNW Islander]

Test run with a 5 gallon tank and new hose.

thank you! Can you give me a little more detail? Five gallon tank? Which hose? Thanks!

 

[racerone]

Sorry----Best take it to a shop.----Most would have gas tanks that they run small motors on.

 

[PNW Islander]

Yes, this is a 250HP outboard.

 

[racerone]

Yes post #1 mentioned a 250 !----Most shops can help you with hooking up a small tank.

 

[chawk_man]

At what intervals are these slowdowns happening? Are you getting any alarms? When is the last time that the high pressure fuel filter was changed?