RPM limitation on 450R
 

Hi Guys , i have some issues with a 450r .After changing several jack plate positions and with the help of trim tabs my outboards doesn't go over 4400 rpm. and no alarms or guardian on Mercury Diagnostic.
My thottle after a certain position does not give signals of increase in power .
Now i have checked the fuel hose diameter and sender and i have noted that the hose internal diameter is 12 mm (requested by Mercury 1/2" ) and the sender on fuel tank is smaller ...only 3/8 " . Could be this the problem of rpm limitation ? Max fuel flow 230 liter/h at WOT and is not possibile in my opinion and too much rpm missed to be a bad pitch propeller .Thanks in advance

What boat is this on and what prop are you running?

Were your throttles calibrated at the time of installation? This needs to be done with the computer hooked up to the motor-there are several steps that the software walks you through. It doesn't sound like it was.

Joe

A friend of ours had a similar problem with his 400r's on his Sunsation CC. What they found on his was a inline fuel filter between the tank and motors that was left in place after it was sold new. They said it was supposed to be removed and never was, causing the motors to limit the rpms due to fuel flow. His were scanned and still showed nothing until one tech thought about the fuel line.

Fuel flow restriction will flag a critical code for fuel flow on the screen.

Joe