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90 HP EFI surging?

jim_n_sc

New member
I have a 2007 90 HP EFI. Everytime I set the rpm at my crusing speed the engine surges up about 200-300 rpm. Only does it the first time then I can adjust the throttle rpm to where I want it. It has done this since new. Any ideas?
 
Yep! If your serial number is in the range of BBCJ-1000001~1006008 and you are in the USA, the ECM most likely needs to be replaced. If it is still in warranty, it should be done by a dealer at no charge. Have them refer to Service Bulletin #61. It only takes a couple minutes to do. This was a common problem with some of the 90's the first year that they came out.

Mike



I do not know if it is covered outside the USA.
 
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The ECU was replaced when I first bought the motor because it was surging at crusing speed. That fixed that problem but it has surged a little when first setting the cruising speed. I have get learned to live with it but would like to get fixed if possible.
 
I have no idea.

If you are near your Dealer, see if they will take a test ride with you. If could be just about anything from the way you operate it, the way the boat rides in the water, or something going on with the engine or controls. If they can see it first hand, there may be a quick solution.

Hopefully, someone else has had this experience and has a solution.

Mike
 
I'm not sure the 90 uses Honda's VTEC system, or not. If it does, then I have found that in certain RPM ranges, the ECM can't seem to make up its mind whether to use the high rpm setting or the low rpm setting, and will tend to hunt back and forth between the two, causing this surge, then backing off. On my BF225 that occurs between 3800 rpm and 4600 rpm - which is where a lot of crusing speeds take place. The surge moves the rpm range up about 150 to 180 rpm, then slowly backs down to where it started. See if that is your case - that the surging only takes place in a certain rpm range. I have found that the surge dampens out after about 5 to 10 minutes of constant throttle.

I'm not sure if there is a fix for this, or not. Next time I get my motor to the dealer, I plan to ask them to try a new ECM to see if that fixes the problem.
 
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