All 4 plugs fire at the same time???

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Model T Ford Forum: Forum 2018: All 4 plugs fire at the same time???
Top of pagePrevious messageNext messageBottom of page Link to this message  By John Gelfer, Milwaukee WI on Sunday, June 17, 2018 - 06:10 pm:

Just put the coil box back on the 1912 firewall after refinishing it. I'm using a True Fire ignition system which works great. It will pop, but not start. Checked the plugs while laying on the head. All 4 spark together all the time. What is going on? The timer is a magnetic button to trigger the spark, so there is no mechanical connection there. A short of some kind?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Peter Claverie, Memphis TN on Sunday, June 17, 2018 - 07:02 pm:

There is absolutely a short of some kind.

With the information you gave, my best guess is the short circuit is in the coil box. Could be a monster carbon track inside, or maybe it got wet inside, or maybe some of what you refinished it with was conductive.

I'd approach it this way: Take all four wires from the timer loose from the coil box, and lay the harness aside. Then turn on the ignition and see what happens. If any or all coils buzz, it's definitely a short to ground in the coil box.

If not, then make yourself a test wire of some sort. Ground one end of it to a convenient place. Turn on the ignition, and touch the other end to each of the top row of connections to the coil box. Each should make one coil (only) buzz.

If that works properly, your short is in the wiring harness or the timer itself. If it doesn't, the problem is in the coil box.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Miller, mostly in Dearborn on Sunday, June 17, 2018 - 07:38 pm:

I don't own a True Fire. But, I'm fairly certain there's a modern TFI module inside that box.

Plugs 2&3 and 1&4 will fire as pairs during each crank revolution because the True Fire operates on a waste spark principle.

Is the green wire going to the #4 post of the coil box also grounded to the chassis per the instructions? This may be causing the fire on all four.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Monday, June 18, 2018 - 12:21 pm:

There does't seem to be any manufacturers support on the Tru-Fire system, posted multiple attempts to contact have failed form the most part,,,, problems will go on without much success.

Maybe time to consider another ignition system form your T. ????????


Top of pagePrevious messageNext messageBottom of page Link to this message  By George n LakeOzark,Missourah on Monday, June 18, 2018 - 01:50 pm:

Research by google had statements that the timing needs to be retarded a little bit more. And the TF needs to have good solid connections. I like mine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Monday, June 18, 2018 - 08:58 pm:

This is the heart of a Truefire system, known as a waste spark system, as one spark occurs just as the exhaust finishes and if it is a little too late, the intake valve is already open and lets the cylinder to backfire through the carburetor, which sometimes causes an engine fire.

It was standard equipment on a number of 12 Volt Ford, Lincoln and Mercury engines from about 1985 to 1994.

It is actually only two coils that fire 1 and 4 or 2 and 3 every time. Two spark plugs divide the AC high voltage output, which means they have to have the same gap to divide the spark evenly and if there is any gap between the coil box terminal and the TrueFire terminals, you lose some of the spark there.

Coil


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Monday, June 18, 2018 - 09:11 pm:

I have installed a few of these for club members.

The only problem is there has to be about 5.5 volts available during cranking the engine, as measured at the starter terminal to ground to allow the built in voltage doubler circuit to produce at least about 11 volts to feed the 12 volt coil units.

Any less than that voltage level, during cranking, will make the engine difficult to start.

Then too, the engine will usually start easily by hand cranking, as the voltage level does not drop for the little amount of current required for the TrueFire operation.

There is still the associated risk of a kick back, if the spark happens too soon, due to the timing not being properly set, so that is more important than noted in the installation instructions.

Our club members are all very happy with their TrueFire performance, once they get a good set of battery cables and a good battery.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Gelfer, Milwaukee WI on Monday, June 18, 2018 - 10:05 pm:

I have loved the True Fire for many years. Always easy to start, no coils to adjust, and no timer to wear out, as there is a magnetic button to trigger the spark. After two days of trouble shooting, I put in an Anderson timer, and coils. It started and runs well on battery and even better on my newly rebuilt magneto. For now, I'm going to run the old fashioned way, and keep the True Fire as a back up that I hope will eventually get repaired.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Tuesday, June 19, 2018 - 08:21 am:

John, I have repaired several of them that only had corrosion on that small ground wire, which resulted in an open circuit.

I was curious to now if that was your only problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Tuesday, June 19, 2018 - 08:53 am:

One more thing that caused me grief for about 10 years was that I painted my coil box wood with black paint.

I did not know that carbon was used to make the paint black.

I did know that carbon conducted electricity.

The engine would run about normal, at an idle, on battery.

When I switched to magneto and reved the engine up, I would get all kinds of bangs and pops.

What a wise old gent told me was, that when I check each coil for spark production, I should also ensure only one spark plug is getting that spark at any given time.

The magneto produced just enough higher voltage to let all the sparks be shared on magneto.

New coil box wood with about 12 coats of polyurethane, sanding every third coat slightly, cured my problem.

I first used liquid black shoe polish to dye the wood black.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 19, 2018 - 11:15 am:

Just a note that Ford did NOT color the wood at all in the coil boxes but soaked the wood in various concoctions of Paraffin or linseed oil all in attempts to ward off dampness. They did NOT paint the wood parts with any sort of black paint or other attempt to make the wood look black. Most of the coatings they used did turn the wood dark eventually but when brand new the coil box wood soaked in paraffin probably just looked like raw wood color. Of course dirt and oil on the wood would soak in too most likely.


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