Hi, I am working on a 1976 Mercury 200(20hp) long shaft, I replaced the coils recently, pulled the recoil and only had my right(facing back of motor) spark plug firing, the left spark plug was dead. I pulled out the ignition wires from the coils, re-inserted, pulled recoil, nothing still. What would not allow that side to fire besides maybe a bad coil? Can someone show me a wiring diagram for this motor and the ignition box, I saw the box had some wires that are not attached to anything. Any help, Thanks a bunch, spring is coming and I would like to go for a nice boat ride!
Do you mean right and left coil? The plugs are top and bottom. I've seen new coils that were bad. Try swapping the coils. If the problem follows the coils, the problem is the coil. If the "bad" coil fires after you swap them, the problem is the switch box or the wire. Laddies is right, all the wires should be connected. If you will post your serial number and the number on the switchbox, we may be of more help. Also, be sure the pigtails on the coils are properly grounded, you may need to sand the paint off of the area where the coil mounts to get a good ground.
Thanks for all your advice, I tried all that was mentioned, I still am only getting the right coil to fire the spark plug. The left coil is not firing the coil, I reversed them and the right only fired. I cleaned the grounds, etc. When I say right, that is me working behind the motor. The model # is 7068821, the grey electrical box p/n is 332-4911A2. I have the green/white wire to the right side coil, the solid green to the left coil. I replaced the wires and new plugs and still nothing. Can anyone direct me where to look next as I am spending alot of time and the wife is already talking about going boating. This motor has not run in two years, I also noted that when I hooked up the fuel and pressured the ball, fuel went into the carb but when I was trying to fire the motor, no fuel was present on the spark plugs but was dripping out of the motor. What also is the compression for this motor?
Not to highjack this thread, but quick question somehwat related to this users issue. Since this may be the switchbox that is keeping the one coil from firing at all, could the switchbox occasionally keep a coil from firing?
I have an 1985 Merc 20hp tiller and it runs great at WOT, but at idle it runs good some of the time and then starts missing on one cylinder part of the time. I hear a ticking sounds when it does this like the sounds of a spark, but cannot find any melted cables on the ignition side of things. The only worn cable I found is on side of the on/off switch is worn through.
311Hemi,
That ticking you're hearing is probably the coil or plug wire arcing to the block. Run it at night and take a look. The spark's origin should be obvious...
- Scott
I would agree it's probably the switch box but heres the test for the system
i see the specs you have here for testing the stator & dva. my question is // does the engine have to be pulled to get this reading???????? im using an ohm meter but not sure im testing right this engine has set up for two years , it ran fine when stored but now it has no fire . i has replaced the switch box so i guess i need stator and coils. if any one has them i would like to buy. serial # is 4292599 any help is appreciated.
1976 Mercury 200(20hp) Ignition Problems!
Linear Mode
