I have a weird problem I have never encountered, my timing light stopped working on plug #1.

I was setting up my points, went to check the timing and the light acted like the switch was bad then stopped working altogether. Got a new one from Autozone, that did not work either! Switched to #4, lamp now works (of course timing marks can not be seen now).

The only thing I noticed beforehand was that when I had the points set to around 18% dwell, the voltage from the (-) side of the coil shot up to 12+/- volts. I think it has an internal resistor circuit because it normally stays around 8-9 volts on the (-) side with 12+ coming into it. The coil is new.

I now have it set at 25% dwell. It is steady and only climbs a bit around 2000 rpms.

New cap
new rotor
new set of points and condensor the other day.

test the plug wire, about 12.5 ohms (also used an old wire - same results)
tested for spark - more than 20kv

removed spark plug, it is fine, except its very black. I know the engine needs more tuning...

wires are in the correct order, tight on cap and plugs. separated with wire looms to decrease any chance of cross-fire.

Rotor points to were #1 should be at 15% TDC and rests evenly on the lobe on the dist. cam.

I have the truck running, though not the best it can be. I just can not time it and I can not figure out why the lamp is not blinking. Both lamps are induction types.

What went wrong?

 

John, try setting your timing on #6 plug wire (directly opposite #1). The crank turns twice for every turn of the cam so the timing there should be the same. If your timing lights don't flash on a plug wire, that is trying to tell you something. Could be either the wire is bad and juice isn't getting through or the plug is fouled/shorted out and there isn't enough voltage on the wire to fire the light. Good luck, I hope this helps.
Greg

'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
huct on foniks wurkt fer mi

 

Thank you, it helped. The plug was fouled so I cleaned it. It still would not fire the timing light. Remembering what you said about the voltage I decided to replace it, even though it was brand new. The plug went bad in the middle of running the truck I guess!

I tested it and got about 5.# ohms from tip to electrode and tested the outside for voltage leakage or short, none. Ceramic looked fine too. Reinstalled, it would only fire the light/work at 1800+ rpms. New plug solved the problem.

I can't even guess how a plug could go suddenly bad. So, I replaced that whole side with new Bosch plugs and will see what will happen next.

I had never thought about using a timing lamp as a test tool, I guess I have a new use for one ;-D

 

What kind of plug went bad. I used to sell bosch but I won't use them. I prefer NGK in the truck and autolites in the stock crown vic. Not trying to start a plug war.

 

Try running the truck at night, in the dark. Raise the hood and look for a leaking plug wire, a blue spark. I suspect that your wire is leaking. The spark is not making it to the plug. Oh, and try moving the timing light pick-up up the wire to see if it will 'find' the place where the spark is leaking.

 

[updated:LAST EDITED ON 06-Jan-03 AT 12:38 PM (EST)]Side note.

If you have a broken plug wire there's a quick way to tell (though it hurts a little).

Start her up and take a wrench in hand. Hold it about a half inch from the rotor cap plugin for each cylinder wire. It'll zap you if the wire is broken.



John

 

> moving the timing light pick-up up the wire to see if it
> will 'find' the place

Yea, I tried that and it did not work. I replaced the wire too and it did not help. I had tested it with a meter and it still tested like it was new. I have ditched the original (new) plug and (new) wire.

The plugs were Autolite 45.

The reason I decided to ditch them was not based just on this freak occurance which has wasted my time and money. On most of the Autolite 45 plugs the anode (-) was not centered correctly over the electrode (+) and I had to twist some of them, left or right, to get them to line up correctly. It just seemed like poor quality work and control and I was not happy with them.

 

 

A battery with a internal short will start your truck but will not fire a timing light. If it was a later model truck that has a ecu it wouldn't start it for lack of internal grounding in the battery. seen it multiple times.