No spark (!@#$%!) and how to bench test switch box?

[rgsauger]

So my rebuilt Carb 2.4 200 has been running great - about done with 10 hrs of break-in. always been 100% reliable.

So last night I was going to set my max timing just spinning the motor over. I yanked the plugs and had the key off. Hooked up my remote start button on the solenoid. Was planning to hook up ground wires to all of the plugs and then timing it with timing light. I was checking my connections on my remote button and inadvertently spun the motor for about 1 second with the plugs NOT grounded. Now, I have no spark anywhere.

I checked the trigger and stator and they ohm'ed perfectly. I checked each coil and same. I can't get spark from any plugs. It's like the key is OFF, but it's not.

Sure would suck if I burned up my switchboxes with one damn bump of the starter. Any ideas on where to look or how to bench test the boxes?

Thanks guys

[WaterZebra]

So my rebuilt Carb 2.4 200 has been running great - about done with 10 hrs of break-in. always been 100% reliable.

So last night I was going to set my max timing just spinning the motor over. I yanked the plugs and had the key off. Hooked up my remote start button on the solenoid. Was planning to hook up ground wires to all of the plugs and then timing it with timing light. I was checking my connections on my remote button and inadvertently spun the motor for about 1 second with the plugs NOT grounded. Now, I have no spark anywhere.

I checked the trigger and stator and they ohm'ed perfectly. I checked each coil and same. I can't get spark from any plugs. It's like the key is OFF, but it's not.

Sure would suck if I burned up my switchboxes with one damn bump of the starter. Any ideas on where to look or how to bench test the boxes?

Thanks guys

Do some continuity checks on your ignition switch? If OK then you probably cooked your switch boxes. Key OFF means no DC power to the switch boxes. The remote starter just jumps power to the starter solenoid. You may have accidentally grounded your ignition circuit which would kill all spark points. Merc OFF switch positions do 2 things. 1 ground ignition circuit for no spark and 2 - sever DC power from the battery. Check your ignition harness connections especially at the + battery connections. Check black/yellow wire connection on ignition harness connections at engine. It should go to ground in the key OFF position. If it is still grounded with key ON then you have a short somewhere in your key switch.

[rgsauger]

Thanks, I'll check that. So black/yellow wires at boxes should be grounded with key off and not grounded with key on?

I hooked my one lead to the input trigger on the solenoid and got 12V+ from the main red wire one the top lug of it. Should not have seen anything else. Key was OFF when I spun it I'm 99% certain.

If key was on and no spark plugs attached to the coils, would a 1 second burst/spin be enough to kill the boxes?

[powerabout]

get a dva adapter for your multi meter, life becomes so easy after that

[WaterZebra]

Thanks, I'll check that. So black/yellow wires at boxes should be grounded with key off and not grounded with key on?

I hooked my one lead to the input trigger on the solenoid and got 12V+ from the main red wire one the top lug of it. Should not have seen anything else. Key was OFF when I spun it I'm 99% certain.

If key was on and no spark plugs attached to the coils, would a 1 second burst/spin be enough to kill the boxes?

1st question Yes
2nd question Never use any 12VDC power supply with your remote starter switch other than the hot side of starter solenoid. I don't know if there was any
back feed into your ignition circuits.
3rd question I don't think so.

[rgsauger]

2. That's where I got my hot for the trigger on the solenoid. I have done that before without incident.

[WaterZebra]

2. That's where I got my hot for the trigger on the solenoid. I have done that before without incident.

Make sure your CD packs and switch boxes have firm connections and are grounded, Just a little corrosion will cause a ground fault. A lot going on with grounding on an engine. I'm beginning to think this problem was brewing before you attempted to time it. Check all of your post and nut connections and for corroded / broken wires. Salt and condensate corrosion can be in a wire even though the insulation is pristine.

[kingsbiship]

Kill switch?

[rgsauger]

Kill switch?

first thing I checked.

[rgsauger]

So I got poking around and the starboard bank of cylinders are all dead. Port is ok. Swapped in an old switchbox of unknown origin and still dead. Going to swap the boxes tomorrow and see if it follows the box. I ohmed the stator last night per the manual and it checked ok. Probably just a bad switchbox that's 30 years old.

Will report back.

[WaterZebra]

So I got poking around and the starboard bank of cylinders are all dead. Port is ok. Swapped in an old switchbox of unknown origin and still dead. Going to swap the boxes tomorrow and see if it follows the box. I ohmed the stator last night per the manual and it checked ok. Probably just a bad switchbox that's 30 years old.

Will report back.

30 year old switch boxes?! You got your $$$$$ worth!

[Tom Foley]

I say stator will be the culprit .

[rgsauger]

I say stator will be the culprit .

Even though they ohmed out ok per the manual?

[Tom Foley]

It's possible . The DVA test is the better of the tests .

[rgsauger]

I'll swap the "known good" box and see if the problem follows the box.