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  #81 (permalink)  
Old 05-25-2019, 09:29 PM
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As I recall, there was a similar issue years ago on some CSX cars. I believe it was determined the problem was in the ignition light housing. Blas
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  #82 (permalink)  
Old 05-25-2019, 10:56 PM
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Originally Posted by patrickt View Post
Alright, I'm now betting on the tach.
Iíll try it tomorrow, but Iím skeptical. I had the tach out of the circuit when I was blowing fuses last weekend.

Iím betting on the fuel sender, the troubleshooting of which was masked by the voltage stabilizer in the circuit.

Hopefully one of us is right!
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  #83 (permalink)  
Old 05-25-2019, 10:58 PM
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Originally Posted by Blas View Post
As I recall, there was a similar issue years ago on some CSX cars. I believe it was determined the problem was in the ignition light housing. Blas

Thanks. Iím pretty sure I already eliminated that as a possible cause, but I donít really trust any troubleshooting I did with the voltage stabilizer installed.
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  #84 (permalink)  
Old 05-26-2019, 12:01 PM
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I took a break yesterday to fabricate a brass tool to loosen and tighten the dash switch nuts. Works pretty well!


Unplugged the tach, still short to ground at heater switch light green wire. Checked light green wire at tach connector--shorted to ground. There are two black wires loose behind the tach. I'm pretty sure they were that way before I started messing around behind the dash, and given that the light green wire is still shorted to ground I doubt they have anything to do with anything.


Unplugged the fuel gauge double green wire. Double green wire shorted to ground. Light green heater switch wire still shorted to ground.

Removed ignition light fixture. Double green wires shorted to ground (wire lug removed from fixture). Center pin green wire open to ground.
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Last edited by ACHiPo; 05-26-2019 at 12:05 PM..
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  #85 (permalink)  
Old 05-26-2019, 12:27 PM
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Alright, what do we have left on there... wiper switch?
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  #86 (permalink)  
Old 05-26-2019, 12:36 PM
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Looking at the picture above, I realized the pink wire that goes to the fuel sender is crimped with the light green wire. As tempted as I am to clip that pink wire to isolate it, I'd rather find a non-destructive way to confirm that the fuel sender is the source of the short.

There is a connection by the driver's side rear wheel next to the fuel line. I'm pretty sure that is the connector for the fuel sender. It's difficult to get to with the car on the ground, but I may be able to disconnect it. Before I do, I want to figure out what the yellow and two black wires are. If they are just redundant for the different fuel sender types I can disconnect them no problem. I'm concerned, however, that the wires may go somewhere else (like the tail lights).
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Old 05-26-2019, 12:46 PM
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OK... if it was me, I'd just cut the pink wire and, if it turned out not to be the culprit, butt-crimp it back together.
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Old 05-26-2019, 01:07 PM
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Alright, what do we have left on there... wiper switch?
Yes, wiper switch and fuel sender seem to be the only things left.
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Old 05-26-2019, 01:10 PM
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OK... if it was me, I'd just cut the pink wire and, if it turned out not to be the culprit, butt-crimp it back together.
May do that. Just thinking through to make sure removing power from the fuel gauge circuit won't mess anything else up.
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Old 05-26-2019, 05:19 PM
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Alright, definitely found an issue with the fuel sender. I cut the wire at the tach, tested continuity and it was open from ground to the pink wire connected to the tach, and shorted to ground on the fuel sender side.

Put a fuse back in #3, turned the ignition to "ON". No ignition light (just dawned on me that I don't have a light because the "I" terminal of the voltage regulator is still disconnected. Will remedy that an report back). Checked the fuse, it's still intact. Started the engine. Charges normally. Turning on the fan causes the ammeter to drop as it should.

That's the good news. Now for the rest of the mystery.

After installing a spade terminal connector splice in the pink wire, I checked continuity to ground again. It's now open.

I turned the key "ON" and connected the pink wire going to the fuel sender to ground and the fuel gauge started rising slowly (the voltage stabilizer is back in the circuit). I started the engine and everything seems normal. The fuel gauge stabilizes about 5/8 which is about right.

Where did my short go?
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  #91 (permalink)  
Old 05-26-2019, 05:54 PM
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Where did my short go?
Jeez. Try wiggling wires to see if you can get the fuse to blow. If you can't, then leave the ignition light disabled and the charging configuration set up so that it works without the light. If you can make it through the summer without blowing the fuse again then you can hook it back up over the winter.
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  #92 (permalink)  
Old 05-26-2019, 07:29 PM
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I'm pretty confident I've eliminated the short, although I suspect I still have a problem with the fuel sender. It almost acts like the fuel sender was acting as a short, but when I cut the wire it somehow reset itself?

Everything is now hooked up as it was delivered with the exception of the pink wire going to the fuel sender, which is floating (disconnected).

The ignition light works properly and the charging system is working correctly. I've run the engine for several minutes, and even took the car for a drive around the block and everything seems to be working correctly (except the fuel gauge).

The fuel gauge worked when I jumpered between the pink wire and the (floating) case of the voltage stabilizer. It also worked when I disconnected the jumper and grounded the case of the voltage stabilizer. I noticed on the test drive (about 5 minutes after the gauge seemed to work) that the needle had dropped back to E.

It seems like the sender pink wire wants to be grounded? I wish I knew why it's changed.

I don't have a problem with that if it works and doesn't cause another problem, but I think I'll hold off making that mod until I talk to Bob Tuesday.

Last edited by ACHiPo; 05-26-2019 at 07:31 PM..
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  #93 (permalink)  
Old 05-26-2019, 07:42 PM
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Originally Posted by ACHiPo View Post

It seems like the sender pink wire wants to be grounded? I wish I knew why it's changed.

I don't have a problem with that if it works and doesn't cause another problem, but I think I'll hold off making that mod until I talk to Bob Tuesday.
On the schematic, the pink wire is hot for a tube-type sender. From the schematic, if you grounded the pink wire it should blow the fuse....
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Old 05-26-2019, 08:28 PM
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On the schematic, the pink wire is hot for a tube-type sender. From the schematic, if you grounded the pink wire it should blow the fuse....
Yep. And yet...

The mystery continues...
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Old 05-27-2019, 05:53 AM
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Well, it could be the sending unit. With the pink wire disconnected, everything except the fuel level meter works perfectly. So, I would try running a fresh, temporary, fused wire to the pink wire connection at the fuel sender unit. Disconnect the existing pink wire at both the dash end and the fuel tank end (just in there's a chaffing fault along it somewhere). Put a five amp fuse on the new fresh wire and run it to the pink terminal at the sender unit and then see if: 1) the fuel level gauge works when the car is on, and for how long, or 2) whether that new fuse blows. If the new fuse works for a while, and then blows, upping the amp value of the fuse might be a possibility to consider... but it is the fuel tank....
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Old 05-27-2019, 08:06 AM
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Originally Posted by patrickt View Post
Well, it could be the sending unit. With the pink wire disconnected, everything except the fuel level meter works perfectly. So, I would try running a fresh, temporary, fused wire to the pink wire connection at the fuel sender unit. Disconnect the existing pink wire at both the dash end and the fuel tank end (just in there's a chaffing fault along it somewhere). Put a five amp fuse on the new fresh wire and run it to the pink terminal at the sender unit and then see if: 1) the fuel level gauge works when the car is on, and for how long, or 2) whether that new fuse blows. If the new fuse works for a while, and then blows, upping the amp value of the fuse might be a possibility to consider... but it is the fuel tank....
Sometime overnight I remembered Doug telling me to remove the connector behind the driver's side rear wheel and short the forward pink wire to ground. If the gauge responded it meant the fuel sender was bad. (This was several weeks ago when I just had a flaky gas gauge).

My guess is that the gauge was not reading correctly yesterday, but was just responding to having the pink wire grounded. If that's the case, then the gauge would have continued to climb to full given enough time.

So I definitely have a bad sending unit.

I still don't understand what happened to the short? I like your idea of running a separate fused wire to to the pink sender, although I think I will try inserting the fuse where I've already cut the wire. I can run a 5A fuse in that wire and a 15A in #3 so the fuel sender fuse would blow first and not impact my charging.

I'm also going to call Bob and Peter first thing tomorrow and get their ideas.

I think I need to drop the tank to replace the sender? At a minimum I will need to get the car up on a lift to access the sender wire at the sender if it seems there is a chafed wire.
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Old 05-27-2019, 09:50 AM
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I still don't understand what happened to the short?
Here is what I believe may have happened: The pink wire that goes to the sending unit from the BATT terminal on the tach normally has 12v+ and is also connected to the green wire there at the BATT terminal as well. When your fuel tank sending unit started to fail, that 12v+ on the pink wire starting shorting to ground, through the sending unit, which blew the fuse #3 and caused all the problems on the green wire circuit. If you try and connect a short, fused wire to that pink wire connector going to the sending unit (and make sure the pink wire that goes to the BATT terminal on the tach has been disconnected) and the fuse either immediately blows, or the fuel gauge works for a while and then blows, then you have found your fault and it is in the sending unit.
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Old 05-27-2019, 09:55 AM
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I have never had to pull the fuel sender, but it is in the center-front section of the fuel tank. Ask Bob and Doug if there's a short cut to working on it. The manual cautions against using non-gas resistant sealant on it, which makes sense....
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Old 05-28-2019, 08:52 AM
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Note the differences in wiring for the Smiths sending unit if you have two wires versus three. And really note the completely non-intuitive installation requirement for the two wire sending unit that you NOT connect the pink wire from the sending unit to the pink wire going to the gauge.

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Old 05-28-2019, 01:42 PM
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An update from yesterday. The problem is not fixed. When I turned the ignition "ON" yesterday, no ignition light. Checked fuse 3 and sure enough it was blown. Replaced the fuse with a 15A one and it blew as well. Changed the wiring back to Bob's recommended configuration eliminating the stator connection on the alternator, removing the "I" spade from the VR, and jumpering the A and S spades on the VR. The pink wire is still disconnected from the fuel sender. The charging works again, but of course no tach or anything else on the ignition circuit.
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