starter keeps turning even with switch off

[bam01]

HI guys Im all new to this site and also a new proud owner of a 77 fj40 I have recently swaped the engine over on her and finally got her running right after a few fuel problems No sooner had I fixed these problems another 1 rares it fugly head...
What is happening now is when i turn the key on it sometimes cranks sometimes doesnt when it does though, when you turn the key off the starter motor keeps cranking.
because it has been lifted and has 35" mudies on you pretty much have to jump into the engine bay to do any work, now it is possible that i have knocked a wire or so loose somewhere along the way, but nothing that I can see?? the only diagnosis iv done on the ignition switch is that working on the theory that all the aux dont work with the switch off so not entirley sure if thats an accurate guess?
If anybody out there has any Ideas all help would be much appreaciated.
CHEERS!!

 

[Red Rattler]

Couple of things to check.
Make sure there are no bits of metal from drilling out holes that are on the starter motor.
Check your wiring see if its all in the right place and that its not rubbed through any where. If you fail to find anything take the starter toan auto elec and get ém to bench test the starter.

 

[Nick the Carpenter]

Welcome. I would say it is the starter switch behind the key, i have had the same problem brought one for $13 AUD.BE carefull i was playing with mine and it started itself, i now have ventilation in my workshop.

 

[bam01]

Yeah had the starter out today and bench tested it seemed fine? the only thing I can think of is the ignition switch

 

[MoCoNative]

I had a similar issue, burned up two starters because of it. My switch was fine, they are pretty easy to take apart and check out. Take the cover off the steering column and you will see the actual switch on the end of the key cylinder, one little screw and it comes off.

What actually caused mine was a bad ground. You mentioned swapping the engine. Did you put the ground strap back on? I ended up putting in new ground straps, one from the starter bolt itself to a bolt below the battery, and then the battery ground to the same bolt. Before I had it set up like stock on my year at least, where the ground strap went from the starter bolt to the frame, and the same for the battery ground, but they relied on the bolts and frame to carry the current back to the battery. If the bolts are getting a poor contact, or the cables are bad, then the juice won't flow right.

You mentioned not starting, that says possible ground. Starter engaging and not disengaging can be ground too, the resistance due to bad grounding, produces alot of resistance in the starter contacts and they weld together, rather than release.

 

[Gumby]

Could be starter contacts. More common on the gear reduction starters, but can happen on any worn out starter solenoid.

 

[theRash]

How often would the guess be in this case that it is starter contacts versus bad ground? I'm interested because I have a similar issue. I'm leading toward bad grounds.
Would welded contacts be detected if a starter got bench tested and passed?

 

[MoCoNative]

I'm not sure on the bench test. Mine did it a few time before I worked it all out, sometimes it would release, or not want to start at all. I took the first starter to fail apart, contacts just looked really bad, but with a good zap of power, they would probably still work at first, if they hadn't been welded many times. My trouble was that mine stuck and ran for so long before I could get the stupid battery cable disconnected, that it melted the selenoid wire and stuff right off the starter, burned up a spring inside too as I recall, so it was detroyed either way. I replaced it, thinking it had just failed, and I fried the next one, a NAPA replacement, not as bad, but still stuck. They tested that one, and said it was a bad starter and gave me another on warranty, I swapped over to a gear reduction after that.

Starts about the same, old versus gear reduction, FYI.

 

[bam01]

I pulled the starter out the other day and gave it a good clean before it all started happining the starter was that caked in mud im surprised it ever turned at all. gave it a good clean and inspection and the normal wear and tear was present nothing too drastic put it back together bench tested it and it was fine. Put it back in the car and thats when it started playing up ayt first the voltameter would drop when you try and start as if there was a short in the line sucking up all the juice. I have one more test to try by bypassing the ignition and running a wire to the exciter on the starter direct from the battery so hopefully this is where the problem lies??

 

[bam01]

well after nearly ripping my hair out I finnally fixed it it turns out it was a combination of bad earth and 1 of the contacts sticking in the starter so thank you to all for your help much appreciated.