1988 Mercury 100 CD ignition backfire through exaust.

dunebug

Cadet
Joined
Jul 26, 2006
Messages
27
I installed new plugs, the wires are as received and seem to be as on a pic I found, no distributer, would it work to start with one plug out at a time to isolate the cylinder.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
You do have the spark plug wires on the correct spark plugs, right? The coils should line up with the cylinders and spark plugs.

Have you tested the idle pickup timing and max timing settings? That would be first. If those are correct, I would think only an ADI component failure would cause backfires. There is a troubleshooting test on the CDIElectronics web page.
 

dunebug

Cadet
Joined
Jul 26, 2006
Messages
27
The troubleshooting test does not mention backfire however I plan to do the ones I can. I found through removing one plug at a time and starting the number 2 has the issue. the ceramic is brown so I presume water contamination is out. The plug was firing while it was out I guess randomly not at the correct time.
 
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