Yamaha 40 (1995)

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clubchuck

Cadet
Joined
Apr 23, 2005
Messages
16
I have a 40HP Yamaha 3 cyl and it seems to run fine at WOT but when trying to start from an idle, it hesitates then suddenly accelerates. This hesitation lasts for approximately 30 seconds. It seems to idle smoothly, but will load up and cut off sometimes if you idle for long periods. Basically , idling does not seem to be the problem but failure to accelerate is definately bad. I am thinking carb problems but was looking for some guidance. Any ideas?
 
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robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Yamaha 40 (1995)

Check fuel system from tank pick-up, primer bulb, quick disconnect on front of motor, fuel filter, fuel pump, bad fuel pump diaphragm, air leaks into fuel system at lines or fittings. If all that is O.K., then carbs may have to be removed and cleaned.
 
9

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,877
Re: Yamaha 40 (1995)

check the timing with a timing light to make sure it is doing what it is suppose to and is at specs and advances properly

Go through carbs and make sure you do the link and sync procedure. Make sure you clean the supply system also otherwise the carbs will catch the trash and need cleaning again.

You can look in the frequently asked questions part of this forum and test the fuel delivery system if you want to make sure there is no problem there.
 
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