75HP 4Cyl 1986 Mariner "reverse" bogging pblm

[SLMPikins]

When starting cold, 3 /4 cylinders run but not the 4TH. Depending on outside air/water temp, after 5-20 minutes the 4th kicks in and then will run fine for the rest of the day. Any insight on troubleshooting this consistent problem would be appreciated.

 

[Texasmark]

You have a thermally sensitive trigger ckt. Swap with another cylinder and if the problem goes to that cylinder you have your smoking gun. I had that happen on my 90 but it was easy to fix as the trigger/high voltage coil and all were in individual (Capacitor Discharge Ignition) modules. Was easy to swap cylinders. Faztbullet can tell you how to make the swap if you have a switchbox where everything is in one big box.

 

[SLMPikins]

TM thanks for the info. Will check in a few weeks and then update the thread with results.