Ford 3000 Gas Hard To Start

STTX

New User
I've never seen this before so I wanted to see if any one has had this issue. I have a 1969 Ford 3000 gas tractor that I got as a project. The tractor has been running for about a year when it started to get progressively harder to start. I pulled the plugs to check for spark and I noticed that while cranking the plugs do not spark. But once I let off the key from cranking the plugs will fire. This explains why the tractor only starts once I've let off the key. To be clear, if I hold the key and crank away the engine will not fire off until I have released the key. Has anyone else seen this before? I am really at a loss to why this is happening. Any help is appreciated.
 
Your symptom is caused by weak ignition, which can be caused by multiple issues, e.g., weak battery, corroded battery cables or connections, undersized battery cables, dirty or misadjusted contact points,
failing coil or condenser, poor wiring or connections in the primary circuit, etc.

If your tractor has a ballast resistor with a cranking bypass circuit (I believe it does), verify that it is connected and that connections and wiring are in good condition.

Dean
 
Yea seen it, more times than I can count. Dean nailed it for you.
Starters draw a lot of current while cranking and sometimes there's not enough current left to get through a compromised ignition system. This leads to no spark, or an extremely weak spark. Sometimes, as you've found, there's just enough revolution of the engine to actually start the tractor when you stop cranking. It can be a bit of an art to let go of the starter at just the right moment :)

Dean listed the usual culprits. In my experience the worst offenders are a weak battery, then burnt or corroded points. Next poss ignition switch. But as Dean said, there can be other and/or multiple reasons.

Tractor manufacturers incorporated the resistor bypass while cranking to provide full current to the coil on systems with a resistor. This actually the best benefit of using a 6 volt coil on a 12 volt system. If you don't understand what this is, post back for more info
 
(quoted from post at 19:07:35 08/02/21) Mine was a flaky ignition switch only powering the ignition in the run position.

That is the way the original key switch was designed to work. They used a bypass wire to power the coil directly with the full 12 volts from the solenoid during starting so there was no need to provide power through the resistance wire during starting. Sounds like your bypass wire wasn't installed or wasn't working and you dropped the voltage to the coil during starting by switching to a key switch that provides power to the resistance wire during starting, or ballast resistor if the resistance wire has been replaced at some point.
 
On my 3000, there is a bypass wire off the solenoid that provides
full power to the coil when starting. Then when the key is released
to the "run" position, the power runs through a resistor wire to
reduce the current through the coil and points to prevent burning.
If yours is set up the same, I would check that wire or the solenoid.
 

Thank you Dean! I am working through all your suggestions and I am beginning to lean towards the ignition switch. I replaced it a few months bacm but I ordered the 5 pin instead of the 3 pin switch. My cheap butt didn't realize it until it came in.
 

Thank you everyone for the help. I'll be looking into this bypass wire tomorrow and I'll let you know what I find. Thanks again!
 
(quoted from post at 18:50:16 08/02/21) Yea seen it, more times than I can count. Dean nailed it for you.
Starters draw a lot of current while cranking and sometimes there's not enough current left to get through a compromised ignition system. This leads to no spark, or an extremely weak spark. Sometimes, as you've found, there's just enough revolution of the engine to actually start the tractor when you stop cranking. It can be a bit of an art to let go of the starter at just the right moment :)

Dean listed the usual culprits. In my experience the worst offenders are a weak battery, then burnt or corroded points. Next poss ignition switch. But as Dean said, there can be other and/or multiple reasons.

Tractor manufacturers incorporated the resistor bypass while cranking to provide full current to the coil on systems with a resistor. This actually the best benefit of using a 6 volt coil on a 12 volt system. If you don't understand what this is, post back for more info


I am in need of help again. I ended up running a wire from fhe "I" terminal of the solenoid to the coil. This helped, if not solved, the hard to start issue with the tractor. My new problem is my voltage regulator burnt up. I replaced the regulator about 6 months ago so I feel like I might have caused it with my new wiring. I did take apart the wire harness and check for cracks or rub-throughs in fhe wiring from the generator to the regulator and to the solenoid. Do you think my new wiring might have caused this?
 
(quoted from post at 11:04:38 09/16/21)
I am in need of help again. I ended up running a wire from fhe "I" terminal of the solenoid to the coil. This helped, if not solved, the hard to start issue with the tractor.
That terminal is the bypass we talked about. The two small terminals are I & S. When "S" receives battery voltage from turning the key switch to start, the relay connects the battery to the starter, turning the engine over to start.
While the engine is turning over, the "I" terminal receives battery voltage and with Negative ground polarity, the wire from the "I" terminal should connect to the negative primary terminal on the coil. This is how the coil receives full battery voltage while cranking. This should be the 2nd wire connected to that terminal on the coil. When the engine starts, and you release the key switch from the start position, the "I" terminal no longer receives voltage and the other wire on that coil terminal continues to provide voltage to the coil. This is usually through a resistor block or wire.

My new problem is my voltage regulator burnt up. I replaced the regulator about 6 months ago so I feel like I might have caused it with my new wiring. I did take apart the wire harness and check for cracks or rub-throughs in fhe wiring from the generator to the regulator and to the solenoid. Do you think my new wiring might have caused this?

There are 3 main electrical systems on a typical tractor.
Ignition system
Starting system
Charging system

When wired correctly, these 3 systems are independent of one another. Running a wire from the starter relay "I" terminal to the the coil would not have anything to do with the charging system.

Why do you think you fried your voltage regulator?
 
(reply to post at 12:47:15 09/16/21)
I took the gen and regulator to a local guy that rebuilds them. When he bench tested both the regulator was not showing a charge.

Thanks for the info on the electrical system. If this ole girl wasn't such a good tractor I'd have put her to pasture. She's just starting to show her age and making me work more. Haha.
 

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