20 year old 50 hp yamaha

[TABS020]

Cleaned carbs ran good until got warm and then no power but idles ok but no power,please help,new gas bulb not collasped ,vent on tank good??????

[Ken]

TABS,
Need more info on your problem.
Are you saying the motor runs fine, gets up to max rpm, but then looses power after it warms up ?
What happens when you give it throttle - does it try to run up on rpm - misses - boggs down ?
If your fuel pump is at least five years old, I would replace it.
If the spark plugs are at least one year old, replace them.
Describe how you "cleaned the carbs"
Ken K [img]smile.gif[/img]

[TABS020]

i pulled the carbs off,and dimantled,cleaned bowls
took floats out and cleaned but didn't take out jets wasn't sure how and it was dark at the lake when I was doing this in the water.So basicaly a half assed job but it worked and then running it the next day warmed up rev's right up and then driving at 3/4 trottle it slowed down to a crawl but idles ok ,tried to go again and just rev's up a bit and no higher,it brought me back to shore anyway,I am going to change plugs ,and should I pull the carb again and do a better job?not 100% sure what I am doing in there,is there possibly some kind of module breakdown happening when it gets warm maybe ??????

[TABS020]

Do you think maybe it's overheating and the alarm is not working ,I sort of remeber last year the alarm when off and I stopped right away ,I didn't know what the noise was haha,started up again and away I went,remeber this motor has had maybe 20 tanks of gas gone threw it only.

[Ken]

TABS,
Check this link - item #16 - the thermoswitch for a 1986 50 hp Yammie:

http://www.boats.net/yamaha/partsyst...mponent=321929

You can disconnect the two wires going to the thermoswitch and short them together with the ignition on and the alarm should immediately sound. If not, then bad alarm/wiring, and your motor may indeed be going into rpm reduction mode.
Also, at the same link, you can find a diagram of the carbs - you need to pull all of the jets and clean them and all orifices.
Good luck [img]smile.gif[/img] ,
Ken K

[TABS020]

If it's the waterpump how can I tell I have a stream of water squirting out the side I am assuming the pump works when you see the stream???

[Ken]

TABS,
The water pump pilot hole dishcharge, aka tell-tale, pee-stream, is an indication the water pump is working, but it does not tell you how much pressure it is putting out.
The best indicator of water pump performance is a water pressure gauge. On average, a strong water pump will register about 5 psi at idle, and 20 at full throttle.
There are several things that can cause an outboard to overheat:
1)weak water pump
2)stuck or clogged thermostat
3)water pump input clogged with debris
4)water jackets clogged with mineral deposits
5)stuck (open) pressure relief valve (I don't
believe your motor has one)

Ken K [img]smile.gif[/img]