03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

RODBOLT
sounds like you are the man when it comes to troubleshooting these outboards...I have done some reading mostly your older post but I have not came up with a definate solution...
1. clean freshwater motor
2. fuel system fine, just clesned the carbs a few outings back and the ran beautifully...I was so proud...and then!
3. first this prob was intermittant as it did it once while I was cruising around at around 3000 to 3500 rpms. power went down and I limped back home. I noticed while power down that the tach had dropped to 0.
4. before I got all the way back she come to life, power back, tach back!
5. soon after she lost power and tach again.
6. loaded up headed home. next day on muffs, all power and tach. put new plugs in and hoped for miracle unfortunitely no miracle....
7. checked spark , identified that there is 0 spark on # 2 and # 5 plus no signal to tach.
8. the yellow limp enabling wire in the rear is connected well it makes no difference if it is plugged or unplugged she runs the same.
9. checked connections on the cps wires and same no difference if it is plugged or unplugged. so I do not know at this point, I was hoping 2 5 and the tach situation would make it stand out...I am leaning toward the cps but i feel like its in slow mode????would slow mode disable the tach?

awaiting feedback at this time....

Thanks in advance for any suggestions available

J

Re: 03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

No RPM reduction will not disable tach. If you have lost spark on 2 cylinders I would suspect the pulser coils. But the only way to determine this is to test there output or less likened resistance. If you have a DVA here are the specs if you have one if not I would measure the resistance of:
W/R-W/G record resistance
W/B-W/L (blue) record resistance
W/Y-W/Br (brown) record resistance
compare reading and see if they are within reasonable ohms spec say 30-75 ohms

Re: 03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

here are the test results:

Note: my model 2003 150 txrb has only White Red White Green & White Yellow White Brown (4 pin plug)

White Red to White Green 33 ohms
White Yellow to White Brown also 33 ohms

2 Green wires coming from Crank Position Sensor 22 Ohms

What are your thoughts??

Re: 03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

Possibly good chance of crankshaft position sensor being problem. Is your full model number 150txrb? That is the service manual I have opened up. Is their anything in front of the 150? Here is the color codes for the pulser coils, see how it lists the cylinder number by the pulser coil and the fact that this is a V6 and does not have #2 and #5 pulser number would lead me to the CKP. But unfortuneately it only gives output voltage of minimum of 3 volts at cranking speed.

Re: 03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

Never mind on model number found it in the same manual. It covered that model number too. See how #4 is the pulser coil, their are only 2. Each charge coil can only power up to 2 cylinders. Being you have 2 charge coils means that your pulser coils controlling 4 cylinders so the CKP has to be telling the ECU when to fire the others. This is all speculation though, the only way to confirm is with a DVA. (direct voltage adapter)

Re: 03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

Thanks for all the info. heres what I found, The CU had 0 signal going in from ignition, so it was simply running the four cylinders from the pulsar coils? The problem I traced back to a dirty pin connector under the helm? once cleaned and reconnected she came back to life! running great.....Gotta love it! anyway seems to have an emergency type set up that will almost always allow you back to the shore. The tach got me thinking and then the fact that the cu did not seem to cahange no matter what was plugged or unplugged except for the 4 wires from the pulsars. with the main connection to the cu unplugged i could not kill the engine with the key..so anyway thanks for all your help, I learned alot...

Re: 03 yamaha 150 txrb, no fire on 2 & 5 no tach signal

lose a pulser coil on that engine and you lose 4 cylinders.
lose a CPS and you lose 5 and 2.
lose a charge coil and you drop all 6.
poorly trained techs irritate me .