Dead Cylinder Mystery

[Jess Willhite]

I have a 98 Vmax with the #4 cylinder not firing. I have fuel, air, spark and good compression. I live in Commifornia so the gas goes bad in like 2 weeks but in this case it sat for 3 months so I replaced the gas and shotgunned the system 3 times now. Can't sync the carbs due to the cylinder not firing. I replaced the plugs and no change. I checked to make sure the air/fuel screw was out the correct turns to make sure I didn't skip that step in the shotgun steps and it is good. I can pull the boot off the plug with no change in rpm on that cylinder and can hear the spark pulse when I pull off the boot. I pull off a boot on any other cylinder and the rpm drops creating a miss. I am at my witts end because it has everything it needs to fire but does not. Please help. Thank You.

 

[Fire-medic]

Try swapping the ignition coil for the bad cyl to another location and see if the miss follows the change. The right front is the #4 cyl. so that makes a plug swap more difficult. You do know that the coil for the #2 (LF) cyl is actually the coil on the RF? And the LF coil fires the RF cylinder?

 

[gentsvmax]

I have a 98 Vmax with the #4 cylinder not firing. I have fuel, air, spark and good compression. I live in Commifornia so the gas goes bad in like 2 weeks but in this case it sat for 3 months so I replaced the gas and shotgunned the system 3 times now. Can't sync the carbs due to the cylinder not firing. I replaced the plugs and no change. I checked to make sure the air/fuel screw was out the correct turns to make sure I didn't skip that step in the shotgun steps and it is good. I can pull the boot off the plug with no change in rpm on that cylinder and can hear the spark pulse when I pull off the boot. I pull off a boot on any other cylinder and the rpm drops creating a miss. I am at my witts end because it has everything it needs to fire but does not. Please help. Thank You.

At minimum I would split the rack, get the #4 carb off and apart for a soak in the carb cleaner. The Ultra-bath is best, ultrasonic with a new kit! Git-er done

 

[Fire-medic]

Our pilot jets don't like sitting idle for months with ethanol fuel. gentsvmax suggestion is a good one, especially about the ultrasonic cleaning. It works.

 

[MaxMidnight]

If it was just a plugged idle jet then I'd expect the cylinder to cut in as the revs are increased.

 

[Jess Willhite]

Try swapping the ignition coil for the bad cyl to another location and see if the miss follows the change. The right front is the #4 cyl. so that makes a plug swap more difficult. You do know that the coil for the #2 (LF) cyl is actually the coil on the RF? And the LF coil fires the RF cylinder?

I will try the swap. I followed the plug wire to the coil to make sure the connection was good on the plug wire also and saw the coils do face opposite ways. I will try swapping wires to see if the problem changes cylinders when I get home. Appreciate the help.