2001 , mercury outboard motor 40hp will only operate at half throttle not wide open

SOURCE: beeping sound from console when at wide open throttle

temp sensor or oil sensor, on that motor, thats gonna be the only 2 options for an alarm. You might need a new water pump impeller or clean the intake out. You get grass and sand etc in there and it will restrict water flow

SOURCE: 40hp 1987 yamaha outboard motor will run for 30-60

Sound like the fuel pump is not keeping up with the engine's demand. Check it out. Good luck. Hope this helps.

SOURCE: replace impellor in yamaha 2 cylinder 40hp

take all bolts out on foot were the two mate drop lower unit down pull impellar cover will be plastic some what roun with a short molded inlet on top when u remove impellar be sure not to lose the key way and when u put the cap on the impellar be sure to rotate it so blades will ben\d in place make sure u dont pintch them when u bolt the cover down MAKE SURE WHEN YOU PUT THE FOOT BACK ON TAT YOU LINE UP THE IMPELLAR INLET WITH THE ONE COMMING DOWN FROM THE ENGINE LINE UP YOUR SHIFTER LINKAGE (TOWARD THE TRANSOM IS WERE IT IS LOCATED bolt it up test with a hose should be good

SOURCE: how to install a throttle cable on a 40hp mercury

Depending on the year you will have to open either an access panel on the control box or the complete control box. The rest is just a matter of fishing the cable from the motor to the console. Connecting the ends is relativaly easy, once you open the control box and remove the engine hood the rest will be easy.

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SOURCE: Need a operation manual for a 1975 Mercury 9.8hp

put it in a water barrel and start ck compression ck for bent prop shaft and water in gear case b/4 u buy