We have a 300 that we have wired for 12 volt with a ballist resistor and an altenator. It is like it starves the coil from power when the starter is engaged and wont fire till we let go of the key. We changed it over to 12 volt maybe 5 years ago and never had a problem till this last month or so. What would a person check first? Thanks, this one has me baffeled. Paul
- Thread starter PaulGinMn
- Start date
Formerly PaMike
Member
Thats how the old 6 volts systems acted. You had to get the engine spinning good, then let off the starter and it would fire. The only thing I can say is go over the whole electrical system. Clean and tighten battery cables, make sure your battery is fully charged and up to capacity.
Owen Aaland
Well-known Member
Since it has been converted from 6 volts, most likely it had a resistor added before the coil to continue to use the original coil. At best you are going to see about half of cranking voltage at the coil. Cranking voltage may be down around 10 volts.
Make sure the points and condenser are in good shape. There should be no more than .1 volt drop across any connection.
If you were to replace the magnetic starter switch (mounted on the starter) volt a 12 volt type with 4 terminals you could add a resistor bypass wire and have full cranking voltage at the coil for starting.
Anonymous-0
Well-known Member
If you have a multimeter, set it to read 12 Volts DC and measure the voltage between the Ign. Switch side of the coil and ground (tractor frame.
When the switch is turned to "Start", if you read zero Volts, you likely have a broken wire between the Ign. switch "Start" terminal that goes to both the starter solenoid and direct to the switch side of the coil (after the ballast resistor). That extra coil wire is used on many ignition systems to put the full battery voltage to the coil only when starting (If yours was wired that way). Then when the switch is released from "Start", the coil gets its voltage through the ballast resistor from the "Run" terminal on the ignition switch.
When the switch is turned to "Start", if you read zero Volts, you likely have a broken wire between the Ign. switch "Start" terminal that goes to both the starter solenoid and direct to the switch side of the coil (after the ballast resistor). That extra coil wire is used on many ignition systems to put the full battery voltage to the coil only when starting (If yours was wired that way). Then when the switch is released from "Start", the coil gets its voltage through the ballast resistor from the "Run" terminal on the ignition switch.
Montana Rancher
Member
For what its worth: I have a farmall 230 that had all the same problems and got the same responses. I had a spare distributer so installed it on the tractor and the tractor started just fine. So what was wrong with the old? All I could find was that the internal shaft and weights were just plain and simply wore out . Just my experience.
APF
APF
rustyfarmall
Well-known Member
You need to wire in a secondary ignition circuit that will provide a full 12 volts to the ignition coil while the starter is running, and then have that circuit disabled after the engine starts. It needs to be in addition to the wire that feeds current to the coil through the ballast resistor.
[Since it has been converted from 6 volts, most likely it had a resistor added before the coil to continue to use the original coil. At best you are going to see about half of cranking voltage at the coil. Cranking voltage may be down around 10 volts.[/quote]
Either way voltage at the coil in run position and no voltage when cranking = bad key switch
Either way voltage at the coil in run position and no voltage when cranking = bad key switch
Where did he say no voltage to the coil while cranking?
Cranking takes a lot of energy, and really draws the battery voltage down while it's happening. 9-10 volts on a 12V converted tractor is typical.
The ballast resistor essentially cuts the voltage in half, so the coil is only seeing around 5 Volts during cranking. Not enough for a hot spark.
Dad's Super M does this too. It's pretty typical.
Janicholson
Well-known Member
Owen's suggestion below, to put a 4 terminal starter relay in place of a 3 terminal design is good. and cheap. Run all wires as they were, but add a 12ga wire from the "I" terminal on the relay to the side of the coil not connected to the distributor.
Adding heavier (0gauge) battery cables will also help. Doing a battery load test is also a good choice, as a bad cell will still crank well, but be low in ignition voltage. Jim
Adding heavier (0gauge) battery cables will also help. Doing a battery load test is also a good choice, as a bad cell will still crank well, but be low in ignition voltage. Jim
Coffeecreek
Member
Ok guy's why are we wiring around the resister , instead of getting a 12vdc coil and throwing the resister away . Seems simpler to me .Poss cheaper too . Just a thought .
Ohiohillbilly
Member
The ballast resistor puts off a fair amount of heat. If you have a coil with an internal resistor all this heat is absorbed into the coil. Also with the resistor and the bypass circuit you will have a hotter spark on startup than with a internal resistor coil.
Janicholson
Well-known Member
When starting, the battery voltage is dragged to 10.8 to 11.5 volts with a good battery. In cold temps, this can be 10 volts, and it also assumes good sized battery cables.
When the resistor is in use on a 12v resistor required coil, or a 6V coil, the lowered voltage is reduced to the point that spark is compromised. Thus a resistor bypass puts puts at least 10 volts into a 6v coil making great spark when needed most. When the key is turned to run, the coil is again given its rated voltage.
When a 12 no resistor needed coil is used this advantage is just not there. It is commonly used on automobiles and has a history of being a standard method of increasing starting reliability. Jim
When the resistor is in use on a 12v resistor required coil, or a 6V coil, the lowered voltage is reduced to the point that spark is compromised. Thus a resistor bypass puts puts at least 10 volts into a 6v coil making great spark when needed most. When the key is turned to run, the coil is again given its rated voltage.
When a 12 no resistor needed coil is used this advantage is just not there. It is commonly used on automobiles and has a history of being a standard method of increasing starting reliability. Jim
Coffeecreek
Member
Thank you sir . Not hard headed , just needed to hear it spelled out . Makes sense now that you 'splained it .
Similar threads
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.
Copyright © 1997-2024 Yesterday's Tractor Co.
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy