1976 850 no fire 1and2 help

[roadlooker]

have a 1976 mercury 85 hp comp 140 all cyl no spark 1 and 2 changed the switch put in new trigger ran the checks that came with the trigger still the same problem check the grounds every thing is grounded to the power head where do i go next please help if any one can

 

[Chris1956]

Re: 1976 850 no fire 1and2 help

That is the four coil motor right? If so unplug the orange wire at the switchbox and see if spark returns. If spark returns, that wire is grounded somewhere between the switchbox adn the ign key, it the ign key is not working properly.

 

[Chris1956]

Re: 1976 850 no fire 1and2 help

Sorry, reread your title. If no fire on just 1+2, go on the CDIElectronics.com website and find the troubleshooting test for your ADI ignition. That should isolate it to a particular part that is not working correctly.

 

[hotrod53]

Re: 1976 850 no fire 1and2 help

When you say no fire in 1 and 2, do you mean that you pulled the plugs and layed them on the block and saw no spark, or you know it's only running on 3 and 4 but did not check the spark? I ask as I try to determine if you have no fire in holes 1 and 2 because you may be running on 1 carb and not 2. If you just pulled the plug wire when the motor was running and it made no change, that doesn't mean that you have no spark, it could mean that you have no fuel. I experienced this in my '77 Merc 500, I found it common that a needle valve in the carb can swell from the Ethanol and stick closed causing you to run on 1 carb/2 cylinders. You can check your coils too, pull your plug wires and measure from the plug wire to ground and then from the input wire to ground, be sure they are all the same. If I remember correctly, mine measured about 950 ohms on the primary to ground. If you have ever run with a bad or disconnected plug wire, your coil will self destruct. (guess how I know that)