1977 JOHNSON Boat motor?

Question

HI. can anyone tell me what a temp, sender is used for on the motor?is it for saftey? so i wont over heat? should i replace impeller and over heat horn? haveing trouble getting up speed at Y.O.T. THANKS IN ADVANCE. PS.RUNS FAST FOR A FEW MIN, THEN SLOWS DOWN.

Answer 1

The temp sender sends a temperature signal from the motor to a temperature gauge and hot horn.  It is very important because overheating the motor evenrually will cause it to blow up.

The impeller should be replaced every 2 years.  The horn is only replaced if it goes bad.

Take it to a dealer to get checked.  There are hundreds of things that can cause the symptoms your motor has.