frustrated 78 Merc 1150

[Davem1754]

After troubleshooting my entire ignition system having no spark( a new switchbox was the problem). The motor now starts and runs on fast idle, but back fires and will not idle. Im not sure to chase a timing issue or carburation.
The motor ran great before I lost spark. I installed new wires,plugs, distributer brush an spring, ignition coil, ignition switch,then a used switchbox.
Spark plug#1 and#6 after running like that was black carboned.The rest ok.
Im not sure how to check the timing, can it be adjusted while motor is running?
I sprayed carb cleaner in each carb(all 3)and the motor wants to kill right away in the center carb, not as much on the top, and doesnt really phase the bottom one much.
Any advise would be appreciated,
Thanks in advance.

 

[Laddies]

Re: frustrated 78 Merc 1150

If the engine ran well before the switch box took a dump, then there is a goog chance the problem with the way it's rinning now was caused by the pearson who repaired it. If at this point the timing screws and belt have not been fiddled with then then firing order and the cap are good places to check.

 

[jimg984]

Re: frustrated 78 Merc 1150

you are not saying what the spark plugs look like,,,,,,carbon deposits?

 

[Davem1754]

Re: frustrated 78 Merc 1150

the #1 and #6 are coated with black residue, thanks.