75 FJ40 Starts but dies when ignition is released (1 Viewer)

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I have a 75 fj40.

It starts but immediately stops running after I release the ignition switch.

1. Battery is new.
2. Starter is strong.
3. If I hold ignition switch on, it will run strong but as soon as ignition switch is released then it dies.

I figure no fuel issue since it will run well and rev up.

Alternator is old. Could be.

Any thoughts much appreciated.
 

middlecalf

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So what’s your starter doing while you keep holding the ignition switch on start and the engine is running?
 
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So what’s your starter doing while you keep holding the ignition switch on start and the engine is running?
Frankly I did not notice if it continues to start or grind in anyway. I wasn’t listening hard for it but probably would’ve noticed that. I thought it was odd that I didn’t notice it continuing to “Start“.
 

Steamer

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Or, if you have a test light or meter, you could turn the key to “on” and check the coil + terminal for voltage.
 

73FJ40

After another night of rust removal!
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Would that be the ignition cable as opposed to the key cylinder?


Would that be the ignition cable rather than the ignition cylinder?

Ignition Switch FJ40, FJ45, FJ55 1972-1984
Both quotes said, "SWITCH". Your link says "SWITCH".

You call it a "cable"? 🤔

The key fits into the lock cylinder. The lock cylinder turns the switch. Any electrical issue involves the "SWITCH". The key turned to "start" energizes certain circuits that are different than when the key is in the "on" position.

That's the basis for the jumper suggestion. If you jump power from the battery to the positive coil terminal, it simulates the key in the "on" position. Just don't leave it there too long, the coil will get really hot.

Using the VOMeter lets you know if power is there as well.
 
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My 74 had this issue, turned out to be a wire that would maintain voltage during run circuit from ignition switch via fuse panel. Already described above. I diagnosed “in the field“ without wiring diagram using a jumper wire bypassing fuse. It would start run up to rpm quick once fired until I let off start to go to run, then it’d die. Turned out to be dirty/corroded fuse contact.
 
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Both quotes said, "SWITCH". Your link says "SWITCH".

You call it a "cable"? 🤔

The key fits into the lock cylinder. The lock cylinder turns the switch. Any electrical issue involves the "SWITCH". The key turned to "start" energizes certain circuits that are different than when the key is in the "on" position.

That's the basis for the jumper suggestion. If you jump power from the battery to the positive coil terminal, it simulates the key in the "on" position. Just don't leave it there too long, the coil will get really hot.

Using the VOMeter lets you know if power is there as well.
My 74 had this issue, turned out to be a wire that would maintain voltage during run circuit from ignition switch via fuse panel. Already described above. I diagnosed “in the field“ without wiring diagram using a jumper wire bypassing fuse. It would start run up to rpm quick once fired until I let off start to go to run, then it’d die. Turned out to be dirty/corroded fuse contact.
My 74 had this issue, turned out to be a wire that would maintain voltage during run circuit from ignition switch via fuse panel. Already described above. I diagnosed “in the field“ without wiring diagram using a jumper wire bypassing fuse. It would start run up to rpm quick once fired until I let off start to go to run, then it’d die. Turned out to be dirty/corroded fuse contact.
I am tackling it tomorrow. will check on contact. some corrosion is likely there.
 
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Update to my issue.

As suggested/instructed, I connected a positive jumper cable from my +battery pole to the coil. At first, I connected to a screw with a green wire attached and got a big spark. I now think that was attached to the igniter so I looked around some more and found a red wire attached to a screw and connected there.

Bingo. The cruiser started first try; let it run for a few seconds and then turned off the ignition. I was surprised it kept running with ignition switch turned off but quickly understood it was being bypassed.

I quickly detached the jumper cable and voila, the engine stopped.

So now I am going to check my fuses right there in the well next to the clutch. I don't really expect to find much and so I guess a new ignition switch is in order. Further info: sits a lot and I have to crank a lot to get it started. Perhaps the wear and tear is responsible, plus the ignition might be only 45 years old I expect! It has the original carburetor.

Any other suggestions? Best place to buy ignition switch?

Is this what I need? It does not come with the key cylinder so I assume I don't have a key/cylinder issue and that it is an ignition switch issue which has nothing to do with the key/cylinder issue.

Click here: Ignition Switch FJ40, FJ45, FJ55 1972-1984

Thanks for all of y'alls (plural) help!
 
Last edited:

Steamer

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So it’s most likely the switch. But, it’s possible there’s a break in the circuit that runs from the switch to the ignition. To test that, you need access to the switch and if you’re there, you may just want to replace the $23 switch and see if it works.
 
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If you look at the wiring diagram...
1603073769919.png

You'll notice that the wire from the ignition switch to the starter continues to the coil. Something about supplying high voltage to the coil when starting?
And another wire to the coil comes from a different position on the ignition switch.
In between these two wires on the coil is, I assume the ballast resistor @igotta40 mentions... Ya, that's probably broken...
 

Steamer

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Thought I'd enhance kerplunk's diagram.
You could test the ballast resistor by using the jumper from your previous test and jump battery + to the resistor terminal that isn't going to the starter. If resistor is good it should stay running.

Ignition 01.jpg
 
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When I first bypassed, I erroneously tried to attach to the green wire connection to the right in the first pic. When it generated a big spark, I then attached to the connection of the red wire to what I now know is the ballast resistor.

That started and kept then engine running until I disconnected the cable.

When first advised to connect +battery to +coil, that ballast connector + screw was the only place I could find to connect to the coil.

So per advice, I will purchase the ballast resistor.

PS: the second pic is the mess of wiring underneath just above the brake pedal, etc.

Thanks.

IMG_8027.JPG


IMG_8022.JPG
 
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Thought I'd enhance kerplunk's diagram.
You could test the ballast resistor by using the jumper from your previous test and jump battery + to the resistor terminal that isn't going to the starter. If resistor is good it should stay running.

View attachment 2469495
Just to follow up. It did continue to run after I started it with +battery to +resistor connection, even with the ignition released. I had to disconnect the cable in order to stop the engine. So if I understand you correctly, the resistor must be good.
 

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