Re: 1991 Yamaha Vx 250
Re: 1991 Yamaha Vx 250
get the winky blinky.
test spark and compression at cranking speed.
if it passes place hull in the water and install the diagnostic test lamp.
make sure the engine can warm up and changes from code 33 to code 1.
if not dont even take it off the trailer.
what we have to do is seperate a fuel system issue and an ign one and they can intertwine on this engine if the ECU sees a cold engine(code 33).
we did have a few running issues with the stators back then.
you will need a peak reading multi-meter or a DVM with a DVA adapter.
what this particular failure is going to look like is a falling peak CDI output voltage over time.
its also why I have 4 of above said meters because that particular engine can have a bank stator charge coil fail and not affect the other bank of cylinders so monitor both at the same time.
running you should see a peak CDI output of about 150V, what will happen is as the stator heats the winding resistance changes and you will see CDI output fall. once it hits about 60V the engine suffers.
now if a Thermostat sticks on the stbd side the ECU will only see it as a cold engine, it will try to fix timing and increase fuel delivery by as much as 20% via the 6 fuel enrichment solinoids and can run #6 fuel bowl dry and create issues./
thats why the diagnostic test lamp is critical for testing on this engine.
if you get a code 9 dont call anyone as its not used but I know what it means now
you can order the test lamp from any yamaha dealer, be aware with the test lamp installed there will be NO automatic oil transfer but all alarms will operate as will the manual transfer switch.
