Yamaha 150 1988

by Mark Renaud
(Naples florida )

Engine will start fine idle fine accelerate fine some days it will run great all day and then like a light switch it won't accelerate above 2500 rpm but still idle fine not skipping . Have gone thru fuel system and even ran it with an external fuel tank and have had the same results some days it key only take about 20 minutes of being on plane before it loses power. I've also changed out the power pack with a new one the stator , the pulser coils , and the rectifier with know good ones . The engines compression is 70 psi on all cylinders. I'm thinking it's going into a fail safe mode but don't know how or why oh yeah and it never loses spark while your checking it.

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Jan 08, 2022
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starstarstarstarstar 		150 v6 2stroke
by: Dieter

Hi all.
Same problem, runs perfect up to 3200 to 3400rpm after that starts to bog, but only after a couple of minutes.
Stripped carbs,checked fuel lines replaced 2x fuel pumps.
It's seems as if the motor wants to cut out electrically, but no alarm buzzer etc.
No heat or oil issues as far as I can find.
What happens electrically when the timing advance activates with second stage carburettor opening, some connection?
Apr 23, 2021
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starstarstarstarstar 		C85TLRQ
by: Karl

My C85TLRQ has the same problem. I also checked the pulse coils, spark plug coils and tried an external tank, no luck. I checked the resistance on the stator, following the Yamaha service manual procedures and found them all to be no where near what the book said they should be. I checked a known good stator from a like engine, the parts are the same, and, the readings were the same as the one on my engine. Not sure what to look at next but going to keep plugging away.
Mar 30, 2021
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starstarstarstarstar 		Same issue
by: Nicholas92

Mine is having the exact same issue. Have you ever solved yours?

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