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1994 Yamaha 2strk 90hp TLRS no ignition when crank position is plugged in

the macheen

New member
1) with all components hooked up and spark checker in place 1&3 will fire about 2 revolutions and quit. engine starts and cuts off
a. disconnect boat harness from engine using jumper wire at solenoid to crank engine with same results.
2) disconnect Crank Position at CDI box and engine has continuous fire on 1 & 3. With boat harness reconnected starts on key and
shuts off properly.
a. connect crank position while running and shuts off engine completely
3) thinking crank position was bad i replaced it and still have same problems
4) i have performed DVA test per Yamaha and CDI manual
a. pulser coil - calls for 7V unloaded i got 12v -----loaded calls for 5v i got 8.7
1) ohm check calls for 220-270 i got 294 i believe to be within 10% and feel it's ok knowing temp and other factors can effect
readings
b. Charge coil -
1) brown to red unloaded calls for 90v i got 93 -----loaded calls for 60V i got 107 with CP disconnected and 83 with it connected
a. ohm check - book says 191-288 i got 84:confused:
2) blue to red unloaded calls for 90V i got 150v --- loaded calls for 100 i got 156 with CP disconnected and 124 with it
connected
a. ohm check calls for 70-90 i got 235:confused:
the ohm readings seem to be backwards and i wonder if this is a misprint in both the yamaha and cdi manuals - i know CDI will reprint Yamaha specs from their manuals

Crank position calls for 5.5v unloaded i got 5.5 ---they call for 5.5v loaded i got 5.7v

I know the CP sensor triggers the #2 cylinder and it should be on by 1500 rpm and you won't see any spark on #2 when cranking with spark checker. but my issue is with CP connected i have momentary fire on 1&3 and that's all

Has anyone experienced this problem - I found an old thread but where it ended there wasn't a solution. any help would be greatly appreciated.

Michael
 
Tps sensor in ECM is bad. Try to find a loaner to verify. Thank's Martin

Thanks Martin,

I wasn't able to find a loaner but have found and ordered a used one (fingers crossed). I will post the end result after i get the CDI and try it.

As a side note the ohm readings i was getting are correct according to the Yamaha tune up spec guide. The ohm readings given in the CDI and Yamaha manual are reversed.

I'm curious as to how you have pinpointed the cause to be the TPS in the CDI box? If you care to, please elaborate.

thanks again,
Michael
 
First the unit is not running yet. You have done your homework as for diagnostics. So using the SWAG method, the next place is the ECM, or maybe not!! Good job!!! Thank's Martin
 
Hi Michael, did the CDi unit resolve the issue ?

I have been working through exactly the same issue so was very pleased to find your thread confirming my thoughts which is good news considering the price of a CDi unit with #2 cylinder not firing at all.

Also agree the documentation is wrong for the resistance measurements - they are the wrong way round !!
 
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