More speed from 9.9 merc

Tommyj11

Recruit
Joined
Jul 28, 2025
Messages
1
I HAVE A 16 FOOT BASS TRACKER 1000LBS. A NEW MERC 9.9 EFI IT RUNS ONLY ABOUT 7MPH. I'M TRYING TO GET MORE SPEED FROM IT. IT ONLY REVS TO ABOUT 3000
I HAVE CHANGED THE PROP FROM A 10X7 TO A 9.25X9
ADJUSTED THE LINKAGE TO OPEN THE THROTTLE FULLY
REMOVED THE AIR RESTRICTOR IN FRONT OF THE BUTTERFLY
RESULTS ARE
MUCH MORE RPMS, CLOSER TO 4000 INITIALLY THE BOAT SPED UP TO 13MPH BUT THE ECU TRIPS AND INITIATES WHAT I ASSUME IS A FAILSAFE, BEEPING AND ROUGH RUNNING CONDITION. I RAN IT LONGER TODAY AND IT WOULD GO INTO THAT CONDITION AFTER ONLY HITTING 8 MPH. THERE IS ALOT MORE RANGE FOR THE THROTTLE TO GO BUT THE MOTOR WONT LET IT. ANY SUGGESTIONS? serial #1A10452BK
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,014
Go down in pitch

That boat is probably rated at 50-60hp. So less than 40hp will be under performing
 
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