Logo

2010 Mercury 9.9 4-stroke No Start

BDT

New member
The engine ran fine for at least 30 minutes one evening. The following morning when attempting to run the engine again it would not start. The carburetor had just been cleaned for the start of the season prior to the evening run. The carburetor has been cleaned in previous years as dried fuel remnants have blocked the main jet. After removing the spark plugs, I noted one plug appeared white in color which indicates a lean condition and the plug gap was approximately .040 and should be .035. A spark plug was left connected to one plug wire/grounded to the engine. When cranked, there was no spark. Tested the other cylinder, no spark. The spark plugs were tested on another engine as good. Ignition coil is Mercury # 803559A02. On the primary side of the ignition coil(orange wire/ground), the resistance reading is 1.2 ohms. On the secondary side of the coil(plug wire/orange wire), the resistance reading shows open circuit on both plug wires. Removed the plug wires from the coil to test independently. Put one probe directly into the end of the plug wire connected to the coil and the other probe inside the spark plug boot and discovered a high resistance on one plug wire and an open circuit on the other plug wire. As the spark plug boot does not appear to be threaded for the plug wire to connect to it, I put the probe through the rubber insulation of the plug wire just before it goes into the boot and that returned a high resistance reading also. But did show a connection. From this I determine there must be a break in the connection just inside the spark plug boot. Testing between the secondary side of the coil(directly to both of the threaded connectors for the plug wire) and the primary side of the coil(orange wire) reads open circuit. Both kill switch circuits were test and function properly. The crank sensor wire(Mercury #16066004) was tested and shows a connected circuit with a low output when the engine is cranked. The ignition coil(Mercury # 803844T01) under the flywheel test as open circuit with no resistance reading but does show a small DC voltage reading when cranked.

1) Does this indicate Ignition coil Mercury # 803559A02 is no longer functioning properly ?

2) Could the faulty spark plug wire have caused a lean condition on the one cylinder and eventually lead to the Ignition coil Mercury # 803559A02 no longer functioning ?

3) Should the ignition coil(Mercury # 803844T01) under the flywheel read a low resistance ohm reading ?

Thanks in advance and happy boating !

.....BDt
 
Back
Top