thunderbolt v problems

[netting one]

Well after many tests and parts i bought the icm!!! This is a 1995 5.7 merc 4 barrel carb, 260 hp bravo lx module. When i got the module the new one is totally different, you have to rewire the main harness and add a bracket to hold the new module and knock sensor. All went good there and started right up. ( nice ) after spending 500.00 so im out all day and things are good untill coming back in. Cruising at 3 grand and 22mph it studdered then the boat slowed down and went off plane. It never shut down but that was really odd. After awhile i thought ok its not going stall out so i gave it more gas and seemed to go back to normal? This also happened the next day same thing? My guess would be the knock sensor but really didnt change anything. I use the valtech 90 fuel also. Im trying to get some info on it before i call the parts guys back. thanks dan

 

[John_S]

Re: thunderbolt v problems

Was your original issue the same or similiar?

There is a troubleshooting procedure for knock module in the service manual.

From memory, the output of the knock module feeds an icm input. It is voltage controlled, and believe it on the same wire as purple/white wire that you ground for base mode timing. You should be able to attach a VOM to that connector and monitor.

 

[netting one]

Re: thunderbolt v problems

Not the original problem. I was heading out after about 70 trips this year and just shut off and nothing. I replaced the dist, pickup,cap,rotor,wires,coil and then came the icm.