2000 Yamaha 4 stroke 40hp overheating

[cnefalcons]

G'day fellow boaters. Engine model F40TLRY manuf 08/99
Need some help please:
Engine overheat alarm comes on within 10 mins of running either idle or faster.
Replaced impellar, old one was 9 years old, have good fast water outlet from the pee hole but still the alarm sounds. Also does the same when using the garden hose as the water source. Any idea's, in a logical order of troubleshooting to resolve this issue?
Thanks

 

[99yam40]

Re: 2000 Yamaha 4 stroke 40hp overheating

If you have not replaced the impeller in 9 years the I take it you have not replaced the thermostat either. Start with that. the manual gives the recommended service for your motor, it would help if you followed it.

 

[cnefalcons]

Re: 2000 Yamaha 4 stroke 40hp overheating

Thanks 99yam40. Have been unable to find a manual that actually covers the 2000. They stop at 1999. Would the 99 work? Did they change the engine much for the 2000 model?
Thanks

 

[99yam40]

Re: 2000 Yamaha 4 stroke 40hp overheating

I could not say since mine is a 99 and I have not looked at a 2000

 

[99yam40]

Re: 2000 Yamaha 4 stroke 40hp overheating

here is a site that may help you. I have not used it because I already have a manual. I just ran across it the other day

http://imracingmanuals.com/yamahaoutboardmanuals.htm

 

[505callyourball]

Re: 2000 Yamaha 4 stroke 40hp overheating

This is purely boat ramp talk, but, recently a guy told me about that problem on his boat. He replaced the impeller and still had the alarm. Turned out to be a bad battery dropping below recommended voltage. I would do the t-stat for sure too but just passing that along...