Ford 8N - Electrical problem. No juice and ammeter buried into negative side.

[Soundguy]

just do exactly as i said.

ground the field, bring rpms up

 

[tmac196]

Field grounded, RPMs brought up...no deflection of ammeter to positive. It drops slightly to negative when ignition key turned, but no other deviation. I attempted to ground the field in many locations, too, just to make sure that I didn't have a bad ground.

On a positive note, I will have access to a multimeter for the foreseeable future.

tmac

 

[Soundguy]

pull belt off gen. disconnect wires.

ground field.

jump bat hot to armature.

it should spin.

post back

 

[tmac196]

It motors easily but it was hard to find a good spot to ground...hmm

I will repeat the full field test again with a known good ground and report back.

 

[Soundguy]

hard to find ground?

what about oh.. the battery post and the stud on the genny frame/bbl that has the ground stud?

 

[tmac196]

hard to find ground?

what about oh.. the battery post and the stud on the genny frame/bbl that has the ground stud?

Sounds strange, but I tried several steel parts on the tractor frame, battery box bolts and the stud on the gennie frame. Either a combination of old paint, rust or crud may have interfered with good contact, because it wasn't until I clipped to the solenoid mount that the circuit was completed and the gennie motored. Finding "good" ground contact may be harder than I realized, so I was wondering aloud if that was part of the problem that I am having.

 

[Soundguy]

genny ground post and battery posts should be the best you can get. anything else is just a middle man

 

[tmac196]

Update:

Full field test performed (field lead on the gennie grounded). Initially, the ammeter deflected sharply to the negative. After two or three seconds, it deflected to the positive and rotated more to the right as I brought the RPMs up:



I shut the tractor off, pulled the ground jumper off the field post and then reattached the field lead. I turned the ignition key and the ammeter needle drifted slowly to the left as it usually does. I restarted the tractor and ran it at moderate RPMs and noticed the ammeter doing this:



That is certainly not normal. When I revved the engine, the needle drifted slightly right, but never to the positive side. When I shut the engine off, I then noted this dreaded finding, again:



This (above) occurred with the engine off and the ignition key off. Once I pulled the power lead off the battery sparks flew and the ammeter looked like this again:



So it appears that something triggered by starting the tractor with the wires on the gennie in their current configuration causes the short.

Where do I go from here?

Why did the ammeter initially drift to the left (negative side) initially during the full field test before rotating to the positive side? What is the significance of this?

So far: gennie has been bench tested-OK
gennie has been "motored"-OK
gennie has been field tested-results shown above
new ammeter installed
new voltage regulator installed
wires between voltage regulator and genie have been continuity tested and
FLD on genie to FLD on vreg
ARM on genie to ARM on vreg
GROUND on genie to apparent GROUND on vreg (to bolt holding vreg to firewall)
final wire at vreg site attached to BAT on vreg.

I am stumped and frustrated. I can publish pics of the wiring on the genie and the subsequent wiring of the vreg if it will possibly be of value.

tmac

 

[kydick]

has your amp meter have 2 screw terminals or does it have a clamp on the back for a wire to run through it? my 8n had a clamp and a wire ran through it. came from the factory that way. replaced it several years ago with the 2 screw terminals type. just unscrewed the wire that ran through the clamp and put it on 1 of the terminals and put another wire on the other terminal and run it to where i unscrewed the first wire. has to be on the right terminals to get the hand to show discharge or charge in the right direction. also it never did show a lot of charge or discharge like the newer vehicles do now but the battery stays up good.
kydick

 

[Midniteoyl]

Have you changed the regulater since you changed the Alt meter? Is it a 'known good'?