115 4 strokes Yamaha missing one cylinder

[Sylva-Ranger]

2001 115 Yamaha 4 strokes, Model F115TLRZ EFI

​Missing cylinder no 2 most of the time. shake, not running well

​Compression 160-165-145-145 PSI

​This engine is in line 4 cylinders, 2x ignition coils ( 1 per 2 cylinders)

I switched the upper and lower ignition coils, and the problem stay on no 2, (and the other cylinder on the same coil seems to run fine).

​i switched fuel injector whit another and problem stay on no 2

is not the spark-plug

checked whith noid light, there is power on no 2 fuel injector.

​Any ideas ?

​the next thing i whil check is the valves clearance but not sure that help (shim adjutment )

 

[charleso]

Did you move the plug wires? Seems pretty much like you have covered all the bases, just wanted to eliminate another simple one that often gets over looked. The only other thing I could think of is the supply to that fuel injector is blocked/restricted somehow.

 

[Sylva-Ranger]

I whill continue to work on today.just receive a new spark-plug set and whant to try before do aniting ..........., before that i just swiched them and problem stay on no 2.

​i whant to check valve adjustment because its good to be done anyways.

 

[99yam40]

valve adjustment might get a little loose after running because of wear, but I do not see it causing a problem you speak of.

I would think if too tight the compression whould show that.

if you have good compression, good spark, and spark at the correct time(timing),
you are left with fuel to air ratio is not what it should be.
too lean or too rich

 

[Sylva-Ranger]

Finaly i put 4 new spatk-plug , adjust the valves, clean/check coil primary conector and some others...........And it run fine now.........i admit i dont know whats hapen exacly because i dont, find anyting that i can see ........

​Put in the lake and make many miles and it run fine again..........

​I suspect a primary wire that was loose a little bit in is conector, but realy not sure.......Timing bealt and timing was ok to .......

 

[charleso]

Glad to hear that the patient is all better. Enjoy.