Uh oh... GT-14 Went POP

[WheelHorseNut 222]

Hey guys -- I was trying to get my 1973 GT-14 up and running again.  It had, what I determined to be, a fuel delivery issue.  I swapped out the pump after figuring out there was no fuel coming out of the hose to the carb.  I took the front end off and realized just how heavy that grille is... haha.

Swapped the pump, changed one of the lines as it was shot after working to get it off, got fuel up to the pump manually and gave it a test crank with my NOCO jump pack hooked up.  After a bit of cranking, it shot fuel out of the line to the carb -- success.

 

Then, I hooked the line back up, got prepped to start it (checked the oil, etc.).  I turned on the ignition and jumped the solenoid (the ignition switch doesn't start the tractor).  The tractor started and was running in spite of itself... it was just barely running and puffing out black smoke.  I checked the choke and the choke cable was stuck in the carb body and it didn't move freely.  I messed with that and got it working.  In the process, I knocked off the coil wire on the terminal with the condenser (the negative side) that runs down to the trigger.  No biggie -- loosened it up, closed the gap on the connector to make it a bit tighter...Then, I hit the jump pack, turned the ignition to on and heard a loud POP -- like a deep pop almost sounded like it came out of the air cleaner, but I'm guessing, maybe the coil?  The coil has been running very hot and I did buy one and a new condenser to replace it.

 

How do I test a coil?  What else could make that sort of pop?

Thanks in advance!

 - Jeff

[WheelHorseNut 222]

Here's the tractor I'm working on:

1973 GT-14 Rebuild Project

[pfrederi 17,116]

In pi one acceptable reading is 6,000 to 10,000

[WheelHorseNut 222]

2 hours ago, pfrederi said:

In pi one acceptable reading is 6,000 to 10,000

 

OK, so my readings were as follows:

in pic 1, 11.11k ohms

in pic 2, 4.9-5.2 ohms  finally settled at 4.9

I don't have the device for test 3, but I may get it just to have as it would seem that my coil is shot, correct?

 

My new Kohler coil reads as follows:

in pic 1, 8.3k ohms

in pic 2, 5.8 ohms

Edited May 22, 2023 by WheelHorseNut

[953 nut 51,472]

The ignition coil for a battery ignition system should have an internal resistor built in that reduces the reading to 3 ohms. A higher resistance may result in less spark being developed because not enough of a magnetic field.

1 hour ago, WheelHorseNut said:

I don't have the device for test 3, but I may get it just to have as it would seem that my coil is shot, correct?

A good spark plug could be used to test spark.

4 hours ago, WheelHorseNut said:

did buy one and a new condenser to replace it.

Be surer the condenser you bought is for a battery ignition system.

The Kohler 230722 Condenser fits all battery ignition single cylinder and twin cylinder from the K-90 to the K-582.  The 235786 condensers are for the magneto equipped Kohler engines only K-161 to K-301

The unit of measure for a condenser is the Farad. Many electronic components like radios and TVs use capacitors that are in the microfarad range (ten to the minus six power Farads) and our small engines use a condenser that is in the nanofarad range (ten to the minus ninth power Farads) which is based on the voltage range they work in. A magneto ignition system uses a 100 to 250 nF condenser and a battery ignition system uses a 200 to 500 nF condenser. A good multi-meter will have a capacitor testing function.

Armed with this information you can walk into your auto parts store and get a very confused look on the face of the person on the other side of the counter. The capacitance is not listed on the package and probably not in any of the on-line data they have for the condensers they stock. You just have to go by the application chart and be sure that the condenser you are buying is for the type ignition system your engine has, not just the horsepower or engine size.

If an engine idles well, but runs erratically when revved up, like it hits and misses, pops and backfires, then chances are, it needs a new condenser/capacitor. And always install a condenser/capacitor with the wire facing downward so rain water and/or when washing off engine, water will not enter inside condenser/capacitor, ruining it. With water inside the condenser, this will also allow it to idle well, but cause it to run erratically when revved up.

What is a farad (F)? A farad (F) is the standard unit of capacitance (C) in the International System of Units (SI). It indicates the ability of a substance to hold an electric charge. The value of most electrical capacitors is expressed in farads, microfarads (µF) or nanofarads (nF)

[WheelHorseNut 222]

17 hours ago, 953 nut said:

The ignition coil for a battery ignition system should have an internal resistor built in that reduces the reading to 3 ohms. A higher resistance may result in less spark being developed because not enough of a magnetic field.

A good spark plug could be used to test spark.

Be surer the condenser you bought is for a battery ignition system.

The Kohler 230722 Condenser fits all battery ignition single cylinder and twin cylinder from the K-90 to the K-582.  The 235786 condensers are for the magneto equipped Kohler engines only K-161 to K-301

The unit of measure for a condenser is the Farad. Many electronic components like radios and TVs use capacitors that are in the microfarad range (ten to the minus six power Farads) and our small engines use a condenser that is in the nanofarad range (ten to the minus ninth power Farads) which is based on the voltage range they work in. A magneto ignition system uses a 100 to 250 nF condenser and a battery ignition system uses a 200 to 500 nF condenser. A good multi-meter will have a capacitor testing function.

Armed with this information you can walk into your auto parts store and get a very confused look on the face of the person on the other side of the counter. The capacitance is not listed on the package and probably not in any of the on-line data they have for the condensers they stock. You just have to go by the application chart and be sure that the condenser you are buying is for the type ignition system your engine has, not just the horsepower or engine size.

If an engine idles well, but runs erratically when revved up, like it hits and misses, pops and backfires, then chances are, it needs a new condenser/capacitor. And always install a condenser/capacitor with the wire facing downward so rain water and/or when washing off engine, water will not enter inside condenser/capacitor, ruining it. With water inside the condenser, this will also allow it to idle well, but cause it to run erratically when revved up.

What is a farad (F)? A farad (F) is the standard unit of capacitance (C) in the International System of Units (SI). It indicates the ability of a substance to hold an electric charge. The value of most electrical capacitors is expressed in farads, microfarads (µF) or nanofarads (nF)

 

The coil I have is a Kohler 4151921-S which is listed on NAPA as internal resistor and for a battery ignition.  I appreciate the info on the condenser.  As luck would have it, I can't locate the one I bought last year, so I will buy the one you suggested.

Thanks!

 

So, do those readings from my old coil sound like it is shot and was likely the pop I heard?

Thanks again!

 - Jeff

[953 nut 51,472]

6 hours ago, WheelHorseNut said:

do those readings from my old coil sound like it is shot and was likely the pop I heard?

They seem close enough to be in the ball park.    Could be the condenser made the pop, check it with your DOM, lots of videos on the internet.

[wallfish 15,905]

Could be all the extra gas loaded into the muffler from the choke being closed then ignition shut off from knocking the wire off.

It'll also load the cylinder with unburned gas too and then it can pop off out through the intake when restarting.

Fire it up and you'll know if anything needs to be changed.

[WheelHorseNut 222]

29 minutes ago, wallfish said:

Could be all the extra gas loaded into the muffler from the choke being closed then ignition shut off from knocking the wire off.

It'll also load the cylinder with unburned gas too and then it can pop off out through the intake when restarting.

Fire it up and you'll know if anything needs to be changed.

Yeah, I never thought about that -- maybe a spark happened when I clicked on the ignition and lit off some unburnt fuel.  That's a possibility...Because the ignition switch will work intermittently -- more often doesn't work than does, but this could've been one of those rare times.

[953 nut 51,472]

11 hours ago, WheelHorseNut said:

ignition switch will work intermittently -- more often doesn't work than does,

Could be some corrosion on the terminals of your ignition switch.

[WheelHorseNut 222]

3 hours ago, 953 nut said:

Could be some corrosion on the terminals of your ignition switch.

That's a good thought, but it's brand new with brand new connectors -- I think it's a wiring issue.  I really want to rewire the whole tractor as it's a mess.  I'm guessing there's a break somewhere in one of the wires.

I'm trying to find a good source for wire that's stranded copper and not ACC.  Amazon is loaded with ACC wire... I'll have to find another source somewhere.

Edited May 24, 2023 by WheelHorseNut

[953 nut 51,472]

9 hours ago, WheelHorseNut said:

a good source for wire that's stranded copper

Del City is a great source for copper stranded wire and the terminal you'll need.  https://www.delcity.net/store/Wire-&-Cable/

[WheelHorseNut 222]

Hey guys,

Just getting back to this and I replaced the coil as I had one already and the condenser, and still no spark.  I am going to change the plug and coil wire because the plug is sooty as can be -- it was running really rich after I changed the fuel pump as I think whatever the ignition issue I was having was causing it to not fire properly.  The coil wire is crazy stiff and brittle.  I'll check it with my meter anyway to see if it is good...

 

What else should I look at?  The rectifier?  Stator?  It could've been the rectifier (it kinda was the vicinity of where I heard the pop).  What other parts could cause it to not spark?  It's a brand new ignition switch... any wiring under the dash or anything?

 

Thanks in advance!

[953 nut 51,472]

8 hours ago, WheelHorseNut said:

The rectifier?  Stator?  It could've been the rectifier

They just recharge your battery, has nothing to do with ignition.

[953 nut 51,472]

8 hours ago, WheelHorseNut said:

What other parts could cause it to not spark?  It's a brand new ignition switch... any wiring under the dash or anything?

With the ignition switch in the run position do you have 12 volts going  to the positive side of your ignition coil? Have you cleaned the contacts of your ignition points by sliding a dollar bill or brown paper bag between them while they are closed? Have you confirmed that the ignition points gap is .020?

[WheelHorseNut 222]

28 minutes ago, 953 nut said:

They just recharge your battery, has nothing to do with ignition.

Yeah, I wasn't sure if any power went through them on its way to the coil, etc.

[WheelHorseNut 222]

36 minutes ago, 953 nut said:

With the ignition switch in the run position do you have 12 volts going  to the positive side of your ignition coil? Have you cleaned the contacts of your ignition points by sliding a dollar bill or brown paper bag between them while they are closed? Have you confirmed that the ignition points gap is .020?

I will check that out tomorrow.  I have to scrape off a bit of RTV to get to the points but I should be able to get to that tomorrow and post here.  I'm anxious to get it running as it's my plow tractor and I need to move some dirt.  It'll save my back a lot of stress.

 

For the points cover, is there a gasket or should I just use a thin bead of RTV?

 

The good news is, I'm slowly fixing some of the crappy makeshift wiring and mismatched hardware fixing all this stuff.  Every time I have to change hardware, I go with stainless... eventually, the whole tractor will have stainless hardware almost everywhere.  The condenser had 3 washers on top -- one was a star washer... The coil bracket had a 6 inch long screw in it... Hey, what do you have lying around in the tool box?  haha 

 

Edited October 11, 2023 by WheelHorseNut

[ineedanother 1,365]

3 minutes ago, WheelHorseNut said:

The good news is, I'm slowly fixing some of the crappy makeshift wiring and mismatched hardware fixing all this stuff.  Every time I have to change hardware, I go with stainless... eventually, the whole tractor will have stainless hardware almost everywhere.  haha 

 

Stainless is nice for a lot of things but it doesn't conduct electricity well so just use regular steel on your grounds and other stuff where you need good conductivity. 

[WheelHorseNut 222]

1 minute ago, ineedanother said:

Stainless is nice for a lot of things but it doesn't conduct electricity well so just use regular steel on your grounds and other stuff where you need good conductivity. 

Yeah, definitely -- I won't use it anywhere wiring is involved.  Just planning ahead when I ultimately take the whole thing apart and paint it -- someday... haha

Edited October 11, 2023 by WheelHorseNut

[WheelHorseNut 222]

I'm also thinking about going this route to replace the ammeter.  I have that bypassed right now as mine is bad.  Lots of possible issues -- trying to eliminate all the possibilities

Speedhut custom gauges

You can upload any graphic you want.  If anyone needs the vector image I made, let me know.

Edited October 11, 2023 by WheelHorseNut
Info about the graphic

[WheelHorseNut 222]

Alright, guys -- she has spark.  I think two things were occurring -- my ammeter bypass was loose.  I fixed that problem and then, when handling the coil wire, I got zapped.  Right in the knuckle... still feeling it... hahaha.  So, that coil wire is getting changed asap and a new plug will also be incoming.  She should fire right up after that!  I'll let you know when it pops off.  Probably be tomorrow!

 

Any of you guys know of a replacement coil wire part number?  Like at Napa?  I had some floating around but I can't seem to locate them (came with a plug wire kit)  I wanted to say someone mentioned a Volkswagen part number but I can't seem to locate it.

 

Scratch that -- I found a great post by @squonk with all the part numbers and info for NAPA.  Thanks Squonk!  Now I get to break out those wire crimping dies I haven't used in 15 years... hahaha

Coil wire info

Edited October 11, 2023 by WheelHorseNut

[WheelHorseNut 222]

On 10/11/2023 at 1:47 PM, WheelHorseNut said:

Alright, guys -- she has spark.  I think two things were occurring -- my ammeter bypass was loose.  I fixed that problem and then, when handling the coil wire, I got zapped.  Right in the knuckle... still feeling it... hahaha.  So, that coil wire is getting changed asap and a new plug will also be incoming.  She should fire right up after that!  I'll let you know when it pops off.  Probably be tomorrow!

 

Any of you guys know of a replacement coil wire part number?  Like at Napa?  I had some floating around but I can't seem to locate them (came with a plug wire kit)  I wanted to say someone mentioned a Volkswagen part number but I can't seem to locate it.

 

Scratch that -- I found a great post by @squonk with all the part numbers and info for NAPA.  Thanks Squonk!  Now I get to break out those wire crimping dies I haven't used in 15 years... hahaha

Coil wire info

OK... I made my new coil wire, got it on there and put some TruFuel in the tank.  I then jumped the solenoid and it wouldn't start.  I took off the air cleaner and put a syringe full of gas in the intake.  She fired up, ran for a little bit and then cut off.  I still have an issue with that damned choke cable.  I got it to run several times doing that with the syringe.  I thought at one point the exhaust smelled like TruFuel exhaust smell when it ran for a bit, so I believe the fuel pump is still working (it was last time I checked after I installed it).  I am thinking this carb needs a rebuild...  Also, when I made my own ignition wire, the nipple that was listed in Squonk's post was a little too small.  It was crazy tight on the wire and the coil.  I am going to try to order this one: BEL 727302 and see if it's bigger than the 727303.  The 727303 is also for 7mm wires and it's $0.10 more, so I'm guessing it's bigger. 

 

So, issues to tackle:

1. Choke cable replacement

2. I have a new throttle cable I need to cut down and install

3. I'd like to rebuild the OEM carb and install the Taiwanese replacement I bought a while ago as a temporary stop gap

4. Figure out why the ignition switch is not turning the tractor over.

Edited October 13, 2023 by WheelHorseNut
Added issues

[953 nut 51,472]

1 hour ago, WheelHorseNut said:

Figure out why the ignition switch is not turning the tractor over.

Is your PTO switch turned OFF ?

[WheelHorseNut 222]

47 minutes ago, 953 nut said:

Is your PTO switch turned OFF ?

It is -- I just went out and checked...  I am going to play around with that tomorrow.  Maybe I'll play with the switch as I am trying to start it with the key.  I think I have a loose connection somewhere because I remembered when I first changed it, it worked a couple times.  Like I'd turn the key and it'd go to crank and stop.  I think there's probably a break or a loose connector somewhere under the dash.  I can't wait to take this whole thing apart someday.

 

I'm charging my jump box now so It'll be ready for tomorrow.

Edited October 13, 2023 by WheelHorseNut

[953 nut 51,472]

1 hour ago, WheelHorseNut said:

I think I have a loose connection somewhere because I remembered when I first changed it, it worked a couple times.  Like I'd turn the key and it'd go to crank and stop.  I think there's probably a break or a loose connector somewhere under the dash.