Remove Governor (rev limiter) on Mercruiser 4.3

[RudyD]

I recently purchased a 2012 Bayliner 215 with a Mercruiser 4.3. It runs smooth, but only revs to 3200 rpm. It was in a rental fleet before (live and learn). I suspect it might have had a speed governor so that renters didn't go too fast. Hoping someone would know how to detect (and remove or disable) a speed governor. I assume there are factory installed rev limiters on these engines (not sure), but guess this is an aftermarket thing added by the rental company. These are the speculations of a novice though (we've all been there at one time) so I'm hoping someone wiser than me in the ways of boat engines might have some insights or advice. Thanks in advance.

 

[alldodge]

might have had a speed governor so that renters didn't go too fast.

Don't think so, but not ruling it out as yet.

What is the engine serial number?
Are you in neutral when reving?
How does it do in the water?

 

[RudyD]

Thanks for the note back. Don't have (but can get) S/N.

I have revved in neutral, same condition. Revs fine to about 3200 and stops.

Same condition in water. Boat gets up to about 32mph (in 45 seconds or so) then stops. (I am also trying a lower pitch prop this weekend - going from 21 to 17 as a test). That might help in water. But given that boat tops out at 3200 rpm in neutral, I feel there is something stopping it. When I learned it was in a rental fleet, I suspected a governor, simply because they used to come on kids' mini bikes and we all learned to disable them when we were kids. Seemed like what a rental fleet might do.

 

[GA_Boater]

If you can, contact the rental company and ask them. I don't think they would use a rev limiter, you never know.

There may be another problem causing the low WOT.

 

[alldodge]

Is the motor fuel injected (MPI/TBI)?
When the key is turned ON do you hear 2 beeps?

If its MPI it may have a "in gear" switch on the shift plate. If it does and the ECM thinks its in neutral it should sound an alarm and slow the rpms.

When it does reach 3200 rpm, is there any beeps or other sounds

 

[H20Rat]

How does the engine sound when it hits 3200? Rev limiters are usually pretty obvious, and generally violent. The engine won't sound smooth at that rpm if it is a limiter.

 

[Scott Danforth]

I know disney uses rev limiters on some boats in the past. its an aftermarket unit. follow the coil wires. would be on the negative side of the coil going to a box mounted near the transom if they added one.

as H20Rat stated, if your hitting a rev limiter, it would go bap bap bap bap bap as the motor bounced against the rev setting.

however most likely there is another issue.

 

[RudyD]

Thanks for all of the input everyone. There are no beeps at WOT or any tapping noises. It's pretty smooth. I'll follow advice to trace coil wires or call former owners. It is fuel injected. Perhaps another problem but I'll continue to hope for any ideas or thoughts. Great group here, I'm very grateful.

 

[GA_Boater]

Did the low WOT show up during the test drive?

 

[RudyD]

Yes, same sitch during test drive. I took a chance, admittedly.

 

[QBhoy]

It sounds very much like it’s in one of the many guardian modes, caused by an underlying fault. There are many things which will trigger the engine into various states of protection.
Get it plugged in.

 

[Scott Danforth]

not sure the bayliners opted for the MPI motors.

correction, see in post 8 its MPI

as Qbhoy stated, you may need to plug Rinda in.