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Need some 640 ignition help

M

Matt in TN

Member
I know we've been through this before. This makes the third time. The thing shuts off on me while running. I'm getting fuel. When I unplug the wire going from the coil to the distributor and set it on the hole where it plugs into, the tractor runs. When I plug it in correctly, the tractor runs for a few seconds and shuts off.

Plug numbers one and four are sooty, two and three are tan. I changes the plugs to new Autolite 437's and the tractor symptoms didn't change. I checked the points gap and made sure it was set to .025. Symptoms didn't change.

I'm now out of ideas.
 
"When I unplug the wire going from the coil to the distributor and set it on the hole where it plugs into, the tractor runs. When I plug it in correctly, the tractor runs for a few seconds and shuts off. " Classic symptoms of a weak spark. What does spark look like? Blue-white, yellow, crack with authority? Several possibilities, depending on what spark looks like.
 
If I have said it once I have said it a million times. Spark needs to be checked. Blue/white and has to jump a 1/4 inch gap or more at All 4 plug wires. From the sounds of it you have weak spark and by pulling the coil wire out you make the spark hotter so it fires. Point may be dirty or need adjusted 0.025 is the correct gap. Distributor car and or rotor maybe going bad
 
Ive found many coil to distributor cap wires open on cars and trucks.Fiberglass wire with carbon will give you much fun.Fake wire measures 10,000 per foot.
 
I put a tune up kit on about 50 hours ago. That included a new rotor and cap from New Holland, and a new coil from NAPA. The tune up came from NAPA as well. Since I've had this issue twice before, I think the problem is somewhere else. Also, the keyed ignition switch is new (50 hours) from nnalert's. It's a CNH product made in India, though.

I've got a busy day today, but I will try to post back here with some spark color info. I'll be out of town this weekend, so I doubt I'll get anything accomplished with the tractor, but I'm interested in hearing your thoughts.
 
Also, I think I'm running old plug wires. There's something special about these wires. I can't remember what the innards are supposed to be made out of. Anybody know? Or know where I can get the right ones? Preferably local as don't want to fool with shipping.
 
when you increase that spark gap you are increasing jump potential voltage at the arc.

i'd say weak sparks and/or fouled plugs.
 
ps. in addition tot hat. doublecheck the key. I've had a bad/loose ignition switch that would jiggle and vibrate and kill ignition. could be source of your weak spark even..
 
Yeah, I need to put a test light on the ignition switch.

I tested the spark from the coil wire against the block. I can get a yellow spark 3/8 of an inch away and no more. When I run the tractor with the coil wire resting on the distributor, the tractor dies after about a minute.

Also, the spark has enough oomph to make me cuss when I get careless. hehe
 
Sounds like you may have found the issue. Yellow spark is weak spark.
This picture is one that UltraDog posted. Shows a nice white spark.
The kind that makes you pick yourself up before you can even cuss!
Wires should be copper core. You can buy it by the foot at NAPA or other
good parts stores. You can also get it in "universal" sets.
You have to put the ends on yourself either way, but it's not hard to do.

17257.jpg
 

Could you define "getting fuel"? I had one that was "getting fuel" turn out to be running out of fuel.
 
Getting fuel = not running out of fuel,; fuel is flowing as Henry Ford intended

So I have weak spark. Am I looking at a new condenser or new plug wires or what?
 

I jus put a brand new NAPA FA66 condenser on and the symptoms haven't changed. Coil wire not entirely installed on distributor and the things runs like a top. Put the coil wire on as intended and the thing dies immediately.
 
(quoted from post at 13:55:44 05/15/13)
I jus put a brand new NAPA FA66 condenser on and the symptoms haven't changed. Coil wire not entirely installed on distributor and the things runs like a top. Put the coil wire on as intended and the thing dies immediately.
Click to expand...
ow can you be sure that you have the correct coil. For example, a 12v coil on a 6v system will have a weak spark. Perhaps try your old coil again? Or if you have an ammeter capable of measuring 5 amps, insert it in the primary wiring & close points & take a reading....ought to be ~4amps.
 
(quoted from post at 11:05:13 05/15/13)
(quoted from post at 13:55:44 05/15/13)
I jus put a brand new NAPA FA66 condenser on and the symptoms haven't changed. Coil wire not entirely installed on distributor and the things runs like a top. Put the coil wire on as intended and the thing dies immediately.
Click to expand...
ow can you be sure that you have the correct coil. For example, a 12v coil on a 6v system will have a weak spark. Perhaps try your old coil again? Or if you have an ammeter capable of measuring 5 amps, insert it in the primary wiring & close points & take a reading....ought to be ~4amps.
Click to expand...

It's been converted to 12 volt and has the right coil. I got it from NAPA.
 
OK, I think I have listed just about all there is to the 'spark' system & a few more. I marked (checked) by those you have said you have checked & cleared. Check the others & then if you still have problems, I expect something was marked checked & verified when it wasn't & needs re-checking, or it is an intermittent connection that you haven't found or bypassed. my 2 cents.

0 coil (for use on 12v w/o resistor) (checked)
0 condenser (checked)
0 rotor (checked)
0 cap (checked)
0 fuel 'through' carb (checked)
0 HV plug/coil wires
0 good elect path from battery to coil (no resistor?) OR temporary bypass path via jumper wire
0 good electrical path from coil all the way to points
0 spark plugs
0 gas tank vented (no sign of vacuum at stall)

P.S. temporarily you can bend coat hangers, baling wire or whatever, so that wires are away from anything & each other & try to run without buying new plug/coil wires, as a test. No need for insulation or copper.
 
(quoted from post at 13:14:22 05/15/13) OK, I think I have listed just about all there is to the 'spark' system & a few more. I marked (checked) by those you have said you have checked & cleared. Check the others & then if you still have problems, I expect something was marked checked & verified when it wasn't & needs re-checking, or it is an intermittent connection that you haven't found or bypassed. my 2 cents.

0 coil (for use on 12v w/o resistor) (checked)
0 condenser (checked)
0 rotor (checked)
0 cap (checked)
0 fuel 'through' carb (checked)
0 HV plug/coil wires
0 good elect path from battery to coil (no resistor?) OR temporary bypass path via jumper wire
0 good electrical path from coil all the way to points
0 spark plugs
0 gas tank vented (no sign of vacuum at stall)

P.S. temporarily you can bend coat hangers, baling wire or whatever, so that wires are away from anything & each other & try to run without buying new plug/coil wires, as a test. No need for insulation or copper.
Click to expand...

Battery to coil voltage is good
Voltage across open points is 12.36
Spark plugs are brand new Autolite 437s
Gas tank vent is fine. No reason to believe it's a fueling issue.
Coil has .004 ohms resistance between the contacts. I don't have the stuff to test the coil tower.

I believe it's either the coil or the plug wires. The coil has less than 50 hours on it, but it's the second coil I've put on in recent times. I may have too much current going to the coil causing it to break down prematurely.
 
0.004 Ohms is waaayyy too low for any ignition coil. Maybe read meter a few decimal points off? If it is IC14 or like coil, designed for 12 without external ballast resistor, it ought to be around 3.25 Ohms across primary terminals.

If it were really 0.004, the current would be 12/0.004 = 3,000 amps, which battery couldn't provide & if it could, the wiring would vaporize!
 
(quoted from post at 13:54:02 05/15/13) 0.004 Ohms is waaayyy too low for any ignition coil. Maybe read meter a few decimal points off? If it is IC14 or like coil, designed for 12 without external ballast resistor, it ought to be around 3.25 Ohms across primary terminals.

If it were really 0.004, the current would be 12/0.004 = 3,000 amps, which battery couldn't provide & if it could, the wiring would vaporize!
Click to expand...

Decimal place was off. It reads 4 ohms.
 
(quoted from post at 16:55:59 05/15/13)
(quoted from post at 13:54:02 05/15/13) 0.004 Ohms is waaayyy too low for any ignition coil. Maybe read meter a few decimal points off? If it is IC14 or like coil, designed for 12 without external ballast resistor, it ought to be around 3.25 Ohms across primary terminals.

If it were really 0.004, the current would be 12/0.004 = 3,000 amps, which battery couldn't provide & if it could, the wiring would vaporize!
Click to expand...

Decimal place was off. It reads 4 ohms.
Click to expand...
reasonable number.
 
Earlier, I listed " good electrical path from coil all the way to points ". You might verify the distributor wall electrical feed-thru bushing & attached copper strip up to points. They get old/brittle & can break or short. Wiggle while checking continuity .........could be intermittent.
 
(quoted from post at 14:05:06 05/15/13) Earlier, I listed " good electrical path from coil all the way to points ". You might verify the distributor wall electrical feed-thru bushing & attached copper strip up to points. They get old/brittle & can break or short. Wiggle while checking continuity .........could be intermittent.
Click to expand...

I just checked and it the continuity seems good and solid.
 
(quoted from post at 17:41:11 05/15/13)
(quoted from post at 14:05:06 05/15/13) Earlier, I listed " good electrical path from coil all the way to points ". You might verify the distributor wall electrical feed-thru bushing & attached copper strip up to points. They get old/brittle & can break or short. Wiggle while checking continuity .........could be intermittent.
Click to expand...

I just checked and it the continuity seems good and solid.
Click to expand...
ell, since all is well, I guess you no longer have any problem, right? :wink:
 

The tractor still won't run if the coil lead is plugged in properly. It will run if the coil lead is hanging loose from the distributor.
 
(quoted from post at 11:03:36 05/16/13)
The tractor still won't run if the coil lead is plugged in properly. It will run if the coil lead is hanging loose from the distributor.
Click to expand...
upposedly we/you have eliminated every ignition related item on the tractor, so either we "just thought" we eliminated some item, it is weak, or it is intermittent. If it were mine I would try a fresh set of plugs (if that not it, save for later use), substitute some wires in place of current plug/coil wires, and put my old coil back & maybe old condenser, too.
 
Its been my experience you have a bad coil. Its been my experience using a spark tester is the best surefire way to diagnose spark. Spark testers are cheap and actuate if it will jump the tester (read the directions) spark is not your issue. Are joint the group that chase their tail on spark issues. BTDT I am no longer in that group a spark tester is the only way to go.

I once read here weak spark will beat the best although he did not say it a Million times maybe he should have your issue is a classic example of weak spark.

Thexton (THE404) Adjustable spark tester.

[/url]
 
(quoted from post at 05:01:57 05/17/13) Its been my experience you have a bad coil. Its been my experience using a spark tester is the best surefire way to diagnose spark. Spark testers are cheap and actuate if it will jump the tester (read the directions) spark is not your issue. Are joint the group that chase their tail on spark issues. BTDT I am no longer in that group a spark tester is the only way to go.

I once read here weak spark will beat the best although he did not say it a Million times maybe he should have your issue is a classic example of weak spark.

Thexton (THE404) Adjustable spark tester.

[/url]
Click to expand...

I put a new IC14 coil in today. Napa was out of the IC14SB. No start. I have a white spark that will jump an inch gap from the coil wire to the block. There is fuel on the plugs, but I can't get the plugs to spark. I put the old rotor button on with the same results. I put the old distributor cap on with the same results. I cleaned almost every electrical connection I could with the same results. The only part of this system that isn't new or nearly new are the plug wires.
 
"There is fuel on the plugs, but I can't get the plugs to spark. "................Well, there is your problem! If there is fuel on the plugs, it is flooded & plugs shorted out with fuel. Like I said on the 17th, "I would try a fresh set of plugs". Preferably with fuel cut off valve closed & using starting fluid & turn on fuel only after it has started on starting fluid. And lay off the choke.
 
(reply to post at 17:31:11 05/21/13)
Click to expand...

So far you are good to the end of the coil wire

What do you get at the end of the spark plug wire.

You should have the same spark as you had at the end of the coil wire.

If you do and don't at the spark plugs what JMOR said he's the man bar none.

I am not much for starting juice in a can, I am addicted to propane and good gas 8)
 
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