frozebubba
New member
Hello,
1992 Mariner 115 hp 4-cylinder with an outboard jet unit, motor Ser. # OD262304.
Have been running this 3rd hand motor about 10 years, 25-30 hours/year.
It has always been somewhat "asthmatic" and runs best at full throttle.
Maximum indicated rpm used to be 5650 (equivalent to harmonic tach reading of 5250 which is book max rpm) but recently it would not exceed 5400 indicated and after it warmed up the rpm would gradually decline to the point I was barely on step in an 18' Alumaweld Intruder, not in carb icing condiitons.
While trouble shooting the problem I removed the airbox cover to check whether one of the carbs was acting oddly.
With the airbox cover removed I got my original rpm back, it runs like a champ and fuel consumption is reduced by one-third.
Local mechanic puzzled but thinks it may be a cracked reed valve in a carb.
Considering the age of the motor, my immediate solution is to just run it and enjoy the improved fuel economy and performance with the airbox cover off.
I might eventually drill holes in front of the carbs on the airbox cover.
Anyone else have a problem like this and, if so, what was your solution?
Thanks
1992 Mariner 115 hp 4-cylinder with an outboard jet unit, motor Ser. # OD262304.
Have been running this 3rd hand motor about 10 years, 25-30 hours/year.
It has always been somewhat "asthmatic" and runs best at full throttle.
Maximum indicated rpm used to be 5650 (equivalent to harmonic tach reading of 5250 which is book max rpm) but recently it would not exceed 5400 indicated and after it warmed up the rpm would gradually decline to the point I was barely on step in an 18' Alumaweld Intruder, not in carb icing condiitons.
While trouble shooting the problem I removed the airbox cover to check whether one of the carbs was acting oddly.
With the airbox cover removed I got my original rpm back, it runs like a champ and fuel consumption is reduced by one-third.
Local mechanic puzzled but thinks it may be a cracked reed valve in a carb.
Considering the age of the motor, my immediate solution is to just run it and enjoy the improved fuel economy and performance with the airbox cover off.
I might eventually drill holes in front of the carbs on the airbox cover.
Anyone else have a problem like this and, if so, what was your solution?
Thanks