TR4/4A TR4A Won't Start

[KVH]

I'm still an amateur.

Car has been sitting for 7 months while I worked on the rear end.

Tried to start it, and it either is getting no gas or has no spark.

It seems to be getting gas.

When I disconnect a plug wire and hit the starter, I'm not seeing any spark. I put a screwdriver in there, and still no spark.

How can this be?

I'm getting hot to the + side of the coil, and negative to the other. I cleaned the pin in the Distributor Cap, and the ground inside the Distributor is in good shape.

Is my coil dead? It's one year old. Any easy way to check?

Anyway, that's my question and where I am. Thanks for any ideas.

 

[Deleted member 8987]

Points corroded?
point gap closed up?
Condenser okay?
Wire to points broken?

 

[Deleted member 8987]

You want I should walk you through it?
I can...so can others.
Not hard.

 

[TR3driver]

What he said.

Two things I'd check first is whether you have 12v across the coil with the points closed (key on of course), 0v with the points open; and whether you have spark when you test directly on top of the coil.

Ok, maybe that's 3 things

 

[KVH]

OKAY: I've got zero volts with the points open, and 11.1 volts with the points closed.

Putting the leads straight to the battery shows 12.6 volts.

I didn't check spark in the middle of the coil yet.

 

[glemon]

Check the stupid human tricks first, I have done it, maybe others too, did you forget to put the rotor back in?

Option two, I have had the pin in the distributor cap fall out or stick, that is of course the super easy stuff, which I like to check before using voltmeters and such.

Also think about any systems you may have disturbed/changed from when it ran to when not, obviously not the rear end, but anything in the electrics ignition system you touched or changed.

Sometimes things just quit on their own, but often times they are disturbed or changed inadvertently when things are taken apart/replaced/bumped while working on something nearbyy etc.

 

[ekamm]

Do your self a favor and before doing anything else see if the car will fire on another fuel source. Maybe carb cleaner or such or try a little fresh gas squirted in the carbs.

 

[TR4]

Starting fluid is a sure fire way to see if you have any spark. If no spark, you might want to check the ground lead wire inside the distributor. I fried mine once when I left the ignition turned on too long. It had turned to dust.

 

[TR3driver]

OKAY: I've got zero volts with the points open, and 11.1 volts with the points closed.

Ok, so that eliminates most problems with the low tension side of things, like an open ground wire or a shorted condenser. Could still be an open condenser, but that would give you some spark (just not enough to start the engine).

If you don't find some spark coming out of the top of the coil, my next step would be to try a substitute coil. There are other ways to test them, resistance tests and whatnot (I think there is even a video on Moss' website), but they aren't always accurate.

If you do find a good strong spark at the coil, then the problem is the cap, wires or rotor. There was a spate of bad rotors a few years back, that would fail by shorting the spark to ground, but still look absolutely perfect.

If you do find a bad rotor, I would also double-check the resistance of the wires, from the cap terminal to the plug terminal. A bad wire can sometimes lead to a rotor failure, especially if you are running a "Sports" coil.

 

[KVH]

I used the Moss Motors video to try a test on the coil. I connected a test wire to the negative and lifted it off and on a ground source with the key on.

While doing that, I held the coil wire near a metal source to watch for sparking.

I could not "see" a spark, but the coil was throwing current. It was nothing like I'm accustomed to seeing. I actually put my finger on the coil wire and just felt a tingle each time.

Does that help?


[I have a hunch I'm missing something simple]

 

[DNK]

Gotta have sparky ,air,and gas to start.
Some forget one of the three occasionally

 

[Deleted member 8987]

And compression.
Now, zero with points open and 11.1 with points closed.

Other way around.
Points closed, they ground, and you should then have zero volts on the distributor side of the coil primary.

Even with dropping resistors, with points open (no load), you should have battery voltage at the coil, unless you've got tach feed off coil.

 

[MikeP]

Make sure too that the 2 wires connecting to the points, from the distributor lead and condensor, are on the proper side of the points insulator. If they're touching the threaded post, or the insulator is completely missing, that will create a dead short.

 

[TR3driver]

I could not "see" a spark, but the coil was throwing current. It was nothing like I'm accustomed to seeing. I actually put my finger on the coil wire and just felt a tingle each time.

Does that help?

That would tend to indicate a failed coil. The problem with that test, though, is that it does not include a condenser in the circuit. Without the condenser, the spark IS very weak.

Basically, the coil only produces a certain amount of spark energy, and doesn't care whether that energy gets dissipated in the spark at the points, or at the plugs. The condenser's main purpose is to suppress the spark at the points so the voltage at the high tension terminal can rise high enough to jump the plug gap.

Anyway, at this point, I would probably try another coil. Your local auto parts store should have one that will do, if you don't want to wait for a "proper" replacement from the usual suspects. However, if you plan to run for more than a few minutes with the FLAPS coil, you'll also need a ballast resistor to go with it. Starting without the ballast is fine, but running that way for very long will overheat the points & coil.

 

[TR3driver]

Other way around.
Points closed, they ground, and you should then have zero volts on the distributor side of the coil primary.

Depends on where you measure from. If you measure across the coil primary, as I suggested above, you'll see voltage with the points closed. And a stock TR4A should have no external ballast resistance, so it should be near battery voltage.

The 1.5 volt drop reported above isn't really very good, but it shouldn't be enough to keep the engine from running either.

 

[Geo Hahn]

This is why you have 2 TR4As... start swapping parts from the runner to the non-starter until both are disabled... then you'll know.

Seriously, I can lend my 'complete ignition system in a hand' if it will help you get it sorted out.

 

[Deleted member 8987]

This is what he said:
"I'm getting hot to the + side of the coil, and negative to the other. I cleaned the pin in the Distributor Cap, and the ground inside the Distributor is in good shape."

That means one side (distributor) is grounded when he measured it.

I said:
"Other way around.
Points closed, they ground, and you should then have zero volts on the distributor side of the coil primary."

As in, zero volts (ground) on distributor side of coil.

That's how points work.

 

[TR3driver]

I didn't say you were wrong, TOC, only that it depends on what you are measuring the voltage relative to. IF you measure the voltage relative to the car body aka "ground" (which actually isn't connected to the ground you are standing on) then you are exactly right.

But measuring across the coil is better in some ways (it rules out a poor connection on the hot side that could read 12v with no load but not supply enough current to run the ignition) and produces the opposite result. That's all I meant.

 

[Deleted member 8987]

Not picking on you or throwing stones.
Just tried to direct his thoughts along the lines of what he said and had done.

 

[HerronScott]

This is why you have 2 TR4As... start swapping parts from the runner to the non-starter until both are disabled... then you'll know.

I subscribe to that theory.

Scott