MF 265 Ignition fuse blowing

[keljan11]

Hi all, the ignition fuse on my 1970's MF 265 has started to blow. I realize I'm looking for a wire that is grounding to the body somewhere, and there aren't a lot of wires on this tractor. I've spent about 4-6 hrs. going over the wiring to no avail. (This tractor does have a cab which does make it a little more awkward).
I finally removed the front end loader to make it easier to see. I still cannot find the issue.

If I put in a new fuse, the tractor will start right up and I can drive around all I want. When I shut down, I can't start it again until I change the fuse. When I do, it's good to go until I shut it down again.

We've had this tractor about 20 years with no major issues until now. (I did change out the starter bendix). Any suggestions out there? Could there be an issue with the altimeter, or the alternator? (They are the originals)

Any help would be appreciated.

 

[Industrial Toys]

Sorry, I cant help. But a neighbor has the same tractor (with cab) and seems to have a similar issue. His fuses are mounted on the dash in a type of consumer electronic rear panel fuse holder. Is that original? I kind of doubt it.

 

[keljan11]

Thanx for the fast reply.
Yes, they are mounted to the dash. I had to take a lot of metal out to be able to see under the dash (and am questioning about putting it all back into place). I just don't want to keep changing out a fuse every time I start the damned thing. Did your neighbor ever figure out a solution, or did he solve it by installing a new fuse holder? I'm running out of: a) ideas b) patience.

 

[thepumpguysc]

I think I would be looking at the back side of the key switch.. seeing it only does it at "shut-down"..

 

[Eagleview]

Hi all, the ignition fuse on my 1970's MF 265 has started to blow. I realize I'm looking for a wire that is grounding to the body somewhere, and there aren't a lot of wires on this tractor. I've spent about 4-6 hrs. going over the wiring to no avail. (This tractor does have a cab which does make it a little more awkward).
I finally removed the front end loader to make it easier to see. I still cannot find the issue.

If I put in a new fuse, the tractor will start right up and I can drive around all I want. When I shut down, I can't start it again until I change the fuse. When I do, it's good to go until I shut it down again.

We've had this tractor about 20 years with no major issues until now. (I did change out the starter bendix). Any suggestions out there? Could there be an issue with the altimeter, or the alternator? (They are the originals)

Any help would be appreciated.

My mind keeps coming back to this bit, "(I did change out the starter bendix)" .

When you put the Solenoid wires back on, are you sure the wire terminals are not touching anything metal ?

I think that fuse is blowing pretty quickly, but as it is a Diesel engine, it just keeps running until you pull the stopper . Then you find the fuse is blown when you try and re start it .

When you say "ignition fuse", you do mean the one that puts the ignition light on and NOT the start fuse that sends power to the Solenoid via a Relay ?

 

[WranglerX]

I would use a test lamp and monitor when fuse blows, that may be clue to what problem is... What is happening in system when fuse blows... When chasing electrical gremlins I find test lamp is best tool ever on non-computer systems...

It's simple to use, put alligator clip on good ground, use probe to test if power (12 volts) is there, lamp on you have power, lamp off there is no power....

Dale

 

[keljan11]

My mind keeps coming back to this bit, "(I did change out the starter bendix)" .

When you put the Solenoid wires back on, are you sure the wire terminals are not touching anything metal ?

I think that fuse is blowing pretty quickly, but as it is a Diesel engine, it just keeps running until you pull the stopper . Then you find the fuse is blown when you try and re start it .

When you say "ignition fuse", you do mean the one that puts the ignition light on and NOT the start fuse that sends power to the Solenoid via a Relay ?

Hey there. Thanx.
I changed the bendix on the starter maybe 1 1/2 - 2 years ago, thinking about it I also changed out the battery last fall, but used tractor to plow snow all winter, and prepped a field to seed this spring, as well as cut/rake/bale a small hay field this year with no issues. (Luckily, the fuse started blowing right at the end of my baling).

If I change the fuse, start it up, run for 5-10 seconds, then pull the stop, the fuse is still good. Did this 4-5 times in a row, but when it runs for a bit then the fuse is blown when I shut down.

To my knowledge, according to the wiring diagram, there are only 2 fuses on this tractor, one for ignition/one for lights, as this tractor is from the 70's. I have Downloaded the MF service manual, and got the wiring diagram from there)
Starting to wonder about voltage regulator/alternator/key switch?, after all this machine is almost 45+ years old and, to my knowledge, original equipment.
Thanx again.

 

[keljan11]

Hey there, thanx.
I've got one of those testers, but have only used it when the circuit has no power where it should have. Will locate my tester and see what I can find out.
Will post the solution when I finally figure it out.

 

[Eagleview]

Have you checked to see how much voltage your Alternator is putting out ? Maybe it is overcharging ?


I once had a similar thing happen to a truck I had . The rectifier in the Alternator went bad and instead of the Alt putting out DC, it was putting out AC which blew a lot of things up on the truck .

 

[keljan11]

I have thought of that. I'm trying to get ahold of one of my neighbors who is a retired automotive/aircraft mechanic, to see if he can come down and take a look. I've also thought of a crapped out voltage regulator and key ignition shorting out as well. Think I've mentioned before this tractor is from the mid 70's (that has been rode hard and put away wet, lol). Haven't had to do much to it except oil changes and a couple of batteries, plus a new bendix, but that was a while ago.
It has really been an excellent tractor for what we've needed it for.
Thanx again for the suggestion. Will post when I find out the cause of this issue.

 

[keljan11]

This (hopefully) will show the wiring diagram I'm using. There is only 2 fuses, and the one blowing is the one off the key.

 

[keljan11]

Yes they are the old 20 amp barrel style. Never thought of that. Will check that out tomorrow first thing (after irrigation sprinklers and feeding the horse).
Thanx.

 

[keljan11]

There are only 2 fuses on this tractor. One for lights and one for ignition. The fuse connections, (barrel style), seem to look okay. Having spent a lot of time checking connections, I've replaced the (corroded) battery ground cable, and have ordered a new alternator (noticed no increased voltage going to the battery). Have also purchased a new key/switch. Will pick up the alternator and instal it tomorrow. Will see what happens next.

 

[keljan11]

Hey all,
Well, after beating my head against various doors/fenders/hoods, etc. I finally figured out where my problems were. I have changed out the negative ground cable, put in another amp meter (out of an old pickup), fixed a couple poor electrical connections. Was still blowing the fuse. Ordered a new alternator, installed it, put a new fuse in, and the issue went away!!
All I gotta do now is put it all back together.