1989 115 6cyl mercury firing only on 1, 3 and 5

[dawwgman]

Thanks jimmbo. I checked the bias on the switch boxes and one was defective. I ran it in the tank with bias wire disconnected and it had fire at all rpms. I installed new (3rd set) switch boxes without idle stabilizer ran for and hr. or more and it ran fine in the tank. I took it to the lake ran fine at idle but would die if you gradually advanced the throttle. I could go from idle to wide open throttle and it would blast off like a rocket, but it did not have the wide open power as before. Before it would go 50 mph now only 40 mph. Haven't checked but I'm thinking timing not functioning properly. The new trigger wires are much to long and have a stiff casing on them causing the advance system to bind and going from idle to wide open instantly over comes most of the restriction. At least its. firing on all cyl. I'm getting there

 

[dawwgman]

This motor is killing me. Did the 464 timing it is correct. Set the timing 6 degree advance. Ran engine in tank anything of idle it would die. Go instantly from idle to wide open throttle it would open on up. Disconnected the bias wire it run as it should. Question why a bias connection. I have disconnected the idle stablizer. I can see the use of a bias wire for the idle stablizer to regulate both switch boxes. This is an idle stablizer not the one that regulates high and low rpm timing. As the trigger determines the timing when the firing occurs why would you need them connected. An engine with 3 cyl. has no bias connection. The 6 cyl. is just a 2 three cyl. engine. This is all new trigger switch boxes and stator never been connected to the idle stablizer.

 

[Faztbullet]

You have to have wire to connect them as this keeps both boxs in time as you only have 3 trigger coils. Below is from AMTECH ignition school

If more than one cylinder is not firing – replace BOTH switch boxes unless you can pin the problem down to the trigger.
Always check the bias circuit: Disconnect the White/Black jumper between the switch boxes and check the resistance from the White/Black terminal on each switch box to engine ground. You should read 14-15,000 ohms on stock switch boxes and 9,200-9,800 ohms on racing switch boxes. MAKE SURE THE READING IS THE SAME ON BOTH SWITCH BOXES! Any problem on the bias circuit and BOTH switch boxes must be replaced as a set.
No Fire on 1, 3, 5 or 2, 4, 6: Swap the stator leads from one switch box to the other. If the problem moves, replace the stator. If the problem remains on the same cylinders, replace the switch boxes. If the stator is replaced and the problem is still there, try another flywheel.
No Fire on One Cylinder: Since this can be caused by a bad blocking diode in the other switch box, disconnect the White/Black jumper between the switch boxes and retest. If all the cylinders are now firing, replace the switch box that was firing all three cylinders originally. To verify this condition, swap the trigger leads around of the switch box that was firing all three cylinders originally. If the misfire moves to another cylinder, the switch box is bad.
Page

 

[dawwgman]

Fastbullet here is history. engine only firing on 1,3 and 5. installed new switch boxes no fire at all yes they were wired correctly ohmed them and one was bad. installed new switch boxes, stator and trigger. fire on 1,3 and 5 again. removed idle stablizer. had fire on all cyl. but would not rev past about 3000 rpm. ohmed switch box one was bad. Installed new switch boxes ran good in tank. Took it to lake idle good even in gear. gradual increase throttle it would die. Go from idle to wide open throttle takes of like a rocket, low on power at top end. Ohm the switch boxes good, checked and set timing 464 method. set timing 6 degree with timing light. Still bogging down at gradual throttle. Will open up going from idle to wide open. Now DISCONNECTED bias wire. Engine runs perfect and smooth. For curiosity while it was running I touch the bias wire to make contact the engines rpm decreased did it several times after 3 times the engine would not change rpms. Disconnected rectifier no difference. Reconnected the bias wire now engine is running as it should. HAHA maybe I reset the switch boxes like unplugging a computer makes it reset. I have no clue. Going to install a new rectifier and all electronic will be new.