FJ55 Alternator/Battery/wiring mystery

[JLB206]

I posted about my new rig over in the IPPS forum, but figure I might get more brain power in a forum for all old LC’s. So a couple weeks ago, I got my new (to me) ‘74 FJ55 almost all the way home from Portland to Seattle, when it stalled on me in Downtown. Let’s not discuss how this could have gone, as the non-highway route takes you through some thick forest and low cell reception areas and I made the drive in the middle of the night. I know-hindsight, etc, but I almost made it!

Anyway, I’m now on my second AutoZone Alternator and still not getting juice out of it. Best I’m getting is 12.2volts.. I can drive it for about 10minutes tops before it stalls and then the battery has to be charged again.

The fusible link seems intact, battery cables were upgraded by PO- nice heavy gauge with little tested resistance. Tested ground and positive between alternator and battery and both sides seem fine. Replaced voltage regulator. Checked all fuses. Even ran a heavy gauge wire direct from alternator to battery to see if that made a differnence- still no juice at Alternator. Actually lower voltage at battery while running than when off (11-11.5 vs.12ish in all scenarios).

Finally got battery charged into acceptable range overnight- 12.75v when pulled charger off, 12.55v after 1 hr, 12.52v after 2 hrs. All connections to vehicle removed so that is just battery ability to hold charge. Could that an issue? Auto parts place tested it when I started this investigation and said the battery was good.

There is some type of battery drain (.2amps so it is significant) but I haven’t been able to diagnose it (combo of low battery voltage and now a blown fuse in my multimeter) other than it isn’t on a fused circuit, so it must be on the main Alt to Battery cable, right? Weird thing is the resistance on the main alternator to battery cable is very low with car off and voltage drop while running also seems fine. I only found the drain when testing amperage draw with negative cables removed from battery post and MM in between. Could that drain be enough to stop the flow of power from the alternator? What else could be screwing this up.

Oh- might be important: PO at some point switched the motor. This ‘74 has a F2 engine. Cruiser Corp indicates there are different alternators right around this time, but the one I have now sure looks like an exact match for what was installed/previously working, except it has an external solenoid of some type attached to the B+ terminal. Photos of new alt. And existing Atl.attached. Also some wiring at Battery for comment.

Any ideas appreciated. Pulling my hair out on this- about to rewire entire system even though It doesn’t seem like the problem.

 

[charliemeyer007]

I'm not overly excited by wing nut connectors, hard to torque properly and low contact surface. You have some sort of ring connector under the lug in pic 4 - you will get better contact/conduction if you put the ring on top.

Buy a 1 wire 90 amp alternator for less than $100 and use a volt meter in the cab to monitor the system - bypasses all that old wire/meters/regulators/headaches.

 

[cruiserkev]

Charliemeyer007 is right. I also went through 2 new auto zone alternators before sucking it up and getting a 100 Amp 1 wire alternator for my 2F. Auto zone sells garbage, those stupid alternators barely charge at all then fried my very spendy Oddesey battery to the point it will no longer charge. They don't get my money anymore, buy a good alternator from one of the vendors here.

 

[JLB206]

I'm not overly excited by wing nut connectors, hard to torque properly and low contact surface. You have some sort of ring connector under the lug in pic 4 - you will get better contact/conduction if you put the ring on top.

Buy a 1 wire 90 amp alternator for less than $100 and use a volt meter in the cab to monitor the system - bypasses all that old wire/meters/regulators/headaches.

I really wanted to find a 1 wire/higher amp alternator that would work, but couldn’t find any vendor that included specifics about mounting bracket, rotation, etc. I also just wanted to get the damned thing running again and was able to pick up the alternator locally. Do you have a make/model recommendation that works on the +/- 3” wide alternator bracket?

All the battery connections are as the PO had it set up- I’d never seen wing nuts on a battery before but haven’t had a chance to change them- I did add lock washers, as the wing nut (and entire terminal clamp for that matter) was loose when the rig died the first time. I’ll try changing the order on the positive- those ring connector wires are the alternator lead and a fused connection to an after market relay that appears tied to the electric fuel pump- haven’t sorted that wiring out yet but it turns on with the ignition- I can hear that.

 

[Pighead]

My first thought is make sure you are not installing internally regulated alternators and then wiring them through the stock voltage regulator. But that's probably not it.
Secondly, there are some very simple tests you can do with a voltmeter to help diagnose alternator problems.
Also, you need to develop a good relationship with your towns best alternator and starter rebuild shop.
I bought a good aftermarket alternator from my local, trusted auto electric shop about 30 years ago. It required a different, matching, voltage regulator. I've heard that the higher output alternators should have new regulators. Had the alternator rebuilt once and replaced the regulator once. It bolted in fairly easily and fits almost like the stock alternator on a 2F block in my FJ55.

 

[ferg]

@Pighead - you belt there is waaay out of line.

 

[Pighead]

@Pighead - you belt there is waaay out of line.

Yup it is. Power steering belt almost as bad.
Someday, I'm gonna fix that.

 

[charliemeyer007]

My favorite gunsmith who sold me my LC favorite saying was "if you have a hammer and a oxyacetylene torch it has to fit". GM/chevy is what they copied so that should be close. Mine came with a Rochester 2BBL and a Delco distributor, The dizzy has a Toyota drive gear but everything thing else is Delco. Modifying a bracket to work correctly shouldn't rocket surgery. Changing the pully to fit the belt might be a little harder such a reaming or bushing it to fit the shaft or it could just work as is.

best deal on one wire alternators - Google Search

 

[knuckle47]

After reading about my own alternator thoughts again and again I came here to say what @Pighead said… find a good alternator rebuild shop. In my previous life, I worked with a trucking maintenance company. Mostly diesels but I found we were replacing alternators almost 1 a month at times. The rebuild they used always had stuff on the shelf that matched our needs and if not….could easily modify our beat up one or one of theirs to accommodate the needs.

As I was reading all of the posts on my other thread, I was thinking about contacting him and asking him to build me an alternator just a tiny step below the max capability of my FJ40 gauges and wiring…like 59.5 amps…

A good rebuilder may help

 

[derail]

I have a 1975 fj55 and had nothing but problems with the external regulator. Eventually I ended up going with a fj60 (infernally regulated) alternator from autozone and did a very minor mod to the old regulator wiring. Works as it should without any problems now. If you want the specifics, let me know. It was easy.

 

[JLB206]

I have a 1975 fj55 and had nothing but problems with the external regulator. Eventually I ended up going with a fj60 (infernally regulated) alternator from autozone and did a very minor mod to the old regulator wiring. Works as it should without any problems now. If you want the specifics, let me know. It was easy.

Turns out my issue was a combo of things: wire between the two coils inside the voltage regulator had a short, so I soldered in a new one (one nice part about old electronics-repairability). Then found that the 15 amp fuse for the circuit that sends 12v to the regulator had been replaced by the PO with a 30 amp fuse. Whether that was too much amperage, or the fuse was faulty, I don’t know, but it would cut out over and over, messing up not only the alternator, but the turn signals, water temp gauge, and anything else on that ignition circuit. Since I put in a 15 amp fuse, everything has worked great!

 

[derail]

Glad you got it sorted out.