Yamaha Phazer - No Spark on 1 Cylinder

Firetrail

Well-known member
Nov 29, 2007
533
124
43
Sioux Falls, South Dakota
I have a 2007 Phazer that only has spark on one cylinder. The sled did run fine but seems to have developed this problem while sitting over the summer. I am stumped. The sled starts and runs fine on one cylinder. Everything else electrical works OK .

* I have narrowed the problem down to the "trigger voltage" at the plug. Both plug connectors have 12 volts at the r/w wire then the key is on. The g/r wire on the right cylinder shows a voltage pulse of what is probably 0 to 12 vdc when the engine is cranking.. That cylinder has spark. The orange wire to the left cylinder has no "pulse" voltage and maybe 100 to 200mv. There is no spark to the orange wire cylinder.
* Both coils are good by ohmage and have been used on the good and bad side. The checking for spark has been done with a spare plug grounded to the sled chassis.
* The wires have been tested from the ECU to the plug connectors. They have continuity and do not show any shorts. If you switch the O wire for the g/r wire the spark will switch sides. I have clipped the O wire and g/r wire at the ECU and the voltages are the same at that point as at the coil connector plug
* The sled does not throw any codes. I thought at that point that the ECU was bad. I tried another ECU that I felt was OK and it does the same thing except it throws a 33 code. That ECU was out of a 2011 Phazer so it may be mapped a little different. I have read that ECU failure is rare and for 2 of them to fail in exactly the same way would be hard to believe.
* The crank sensor ohms out as OK.
* I removed all the ground wires from the "yellow" block and soldered them in bundles of 4 to heavy wire and ran them directly to the battery.

Is there something obvious that I am missing? I have spent many hours tracing wires and cleaning plugs to no avail. I think I need some fresh thoughts on this. Thanks
*
 
Last edited:

Firetrail

Well-known member
Nov 29, 2007
533
124
43
Sioux Falls, South Dakota
Repair

After a few months of trying to figure this out I finally have some resolution. There was a loose pin on the small wiring connector where it goes into the ECU. There are about 12 wires on the small block. Not positive which one it was but I redid all of them. This was only found after I started the sled on one cylinder and started "wiggling" wires until the sled started running on both cylinders. Not very professional but effective.
 
Premium Features