1978 80 HP Merc Cylinder cuts out

[hh810]

When I first start out cold it seems to run and start fine but when you go to take off is when you notice you are low on power. At first it was like running on 2 or 3 cylinders until you go wide open for about 300 yards then like flipping a switch, FULL Power kicked in. it was like this for about 6 tanks of gas. Now you can drive all around the lake on 2 or 3 cylinders then stop the motor for 3 to 5 minutes restart and will run good the rest of the day. Only once just recently did it cut out for about 5 seconds while driving after warm up.

 

[jeff_smith_0423]

Re: 1978 80 HP Merc Cylinder cuts out

I'm assuming you've run a compression test and that your fuel system is clean and in good working order.


I've had this problem on two motors and it's always been ignition related. As you've probably read and seen on here, do all of the ignition diagnostics in your service manual, as well as the DVA tests from CDI. I have a guess as to what it is, but the diagnostics will tell you for sure.