1995 90HP Yamaha - Bypass Mode

[90HPYam1995]

Robert

Thanks - sure have learned alot in this process and will be sure to keep checking back - but will post something up Mid July once I get it back from shop.

If car dealers had this long a wait they would be out of business.

[rodbolt17]

car dealers dont have so much seasonal work.
have you actually tested spark? maybe use a Kv tester on it while running.
the old pull the plug wire off trick wont work.
when the engine is started cold does it rev up then idle back down?

[90HPYam1995]

Rod

With everything hooked up correctly, the motor will fire for less then 1/2 second, and just cut off. It will run fire and run on 2 cylinders when the yellow wires (bypass) are disconnected on the CDI.
I can get the motor to run at 2000 rpm - all hooked up normally - but have only tried this once - obviously since not good practice.

Just frustrating - but patiently waiting on the dealer.

[robert graham]

Read very carefully any responses from Rodbolt, since he has a real in-depth understanding of the mechanical and electrical functions of these motors. Hopefully he may provide some ideas or answers for you. Good Luck!

[rodbolt17]

you have replaced the entire spark producing spark con*****ing devices on that engine.
use the dealer locator function and find a dealership with a master tech.
unlike in the past with various other brands, you cannot buy or wing through the yamaha master tech test.
the failure rate is about 80%.
so those that make it know what they are doing and then there is a matter of pride.
and ego .
not that I have one.
conciet is a fault and I have no faults .

[robert graham]

Bypass is different then safe mode - safe mode is oil or high temp which it is not, I have traced that until blue in the face.

As for Bypass - the book says a timing issue - and all of that has been replaced, recommended by the dealers I have had to use to this point.

Please let us know what you find out about this, especially since I run the same motor and very curious what might cause this problem? Good Luck!