1995 Yamaha 70HP TLRT will not advance.

[cclemens]

The symptom:


Cold engine throttles up and runs under load for a good while. Can and will power down and power backup with no stalling, sputtering, or otherwise noticeable problem. Once hot the unit will lose power even while on plane. When throttle is advanced “bogging down” symptoms get worse. Engine will stall unless put into idle then can be advanced again but only carefully. Whether or no it will get back on plane seems arbitrary. It did this for the better part of a year until finally now it will not advance at all under load. Now it sputters and stalls It will run continuously slightly above idle.

Things I have done:

1. New fuel line and squeeze bulb
2. New water separator
3. New Fuel pump
4. Cleaned fuel filter
5. Rebuilt Carbs
   1. Fuel was pooling around intakes and poured out when tilted.
      1. All new gaskets.
      2. New needles
      3. Adjusted floats
   2. Ran under load with top open to see fuel spray which looks good.
6. Tested compression
   1. Plugs Fouled brown/black greasey
      1. Service Manual says bad spark.
7. Tested Ignition coils.
8. Reseated Caps
9. New Plugs
   1. Properly Gapped.
10. Tested Crank Position Sensor
11. Testing CDI

I am mostly convinced something is CAPUT in the CDI. I think this because of the progressive dying, temperature factor to failure, and exhausting fuel issues.

Any Thoughts?

 

[racerone]

What condition is the water pump in ?---What are the results of a compression test ?

 

[cclemens]

I have no idea about the water pump but it never over heats unless I suck up a bunch of pluff mudd which I did once. As far as compression goes I have a shop manual and they were within specs but I do not remember the exact numbers.

But now that you mention it the motor does act like there is an alert. Either low Oil in the reservoir or that is overheating but no heating alarm. Maybe one of those sensors went bad and is tripping some safety thing...... Hmmm I will try testing those sensors when I get home.