I am in the process of buying a Chrysler boat with motor, I tested compression and it is good so I decided to move forward. The motor turns on but backfires and am thinking it might be the timing or firing order. I have never worked on an outboard motor but do have good knowledge of auto engines. Does any body know the firing order for a 4 cyl Chrysler 100 HP? I would really appreciate any help. Thanks!!!!!