Usable fuel tank capacity in '68 IIa 88"

[cedryck]

[QUOTE=gaxdad;109068]Looks like your insight on the voltage stabilizer was accurate. I found it in a different place than the service manual diagram indicated. Disconnected.

Attachment 12427

I'll have to hook it up and test it. I have a suspicion that it may not work and thus was bypassed.

Thanks for the insight and advice.

Wes[/QUOTE

Hook it up, should make a difference.

[lumpydog]

That's actually the right place/location for the stabilizer and is where it's located in my truck (I've seen it in the same location in other 68s - so I believe that to the be the factory location). The way yours is setup - it's probably taking a straight 12V which will not allow the instruments to work properly - if at all.

For peace of mind - I'd get the Moss replica. Either way, make sure it is grounded - as your current unit is - to the firewall. Dark green wire (12v source) goes to the "B" terminal on the stabilizer. And then a lighter green wire goes from the "I" terminal on the Stabilizer to the Fuel Gauge and another light green wire goes from the other "I" terminal to the temp gauge.

Alternatively, you can go single wire from "I" post to fuel or temp gauge and then jumper a light green wire from one gauge to the other gauge.

[Edit] P.S. It's a good idea to take the negative lead off the battery terminal when you mess with the wiring. Don't ask how I know this ;-)

[gaxdad]

I dug into the rats nest in my dash and hooked up the voltage stabilizer this afternoon. The results weren't conclusive.

I connected the green wire that was connected to the fuel gauge to the B terminal. (After a bit of detective work to confirm that I had B and I sorted - since they aren't labeled. ). I then connected new leads from the I terminal to the fuel and temp gauges.

Once I started the truck the fuel gauge indicated ~ 1/2 tank ( the tank is almost full). The temp gauge didn't do a thing even after I let the engine warm up.

Voltmeter:

I checked the voltage stabilizer with an analog meter. The needle vacillated between 10 and 12+ volts. I assume this is a positive sign.

Fuel Gauge

I also checked the fuel gauge while connected to the voltage stabilizer (same behavior). I also tried with the fuel gauge connected without the voltage stabilizer - a steady 8 volts. Hmmm.... then I realized that I DON'T have a Smiths fuel gauge. It is labeled British Jaeger. I need to research this and determine whether this gauge requires alternate voltage vs Smiths. My initial search turned up nothing but eBay listings and other sales sites. For all I know they are just Smiths gauges with a Jaeger label.



Temp gauge:

I need retry this test with the voltage stabilizer. I tested with the voltmeter and got the same vacillation between 10 - 12+ volts. But I'm not sure I had the right connection. I retested without the stabilizer and got a steady 12 volts (between either of the terminals with green wires and the black connection that I believe is the ground and the sender to the temp sensor).

Here is is a picture of the connections on temp gauge. I had no luck finding any documentation in the web indicating the wiring labels for each terminal. I'm hoping that someone here can help me sort which is the correct one to connect to the I terminal.


(Temp on the right. Oil on the left (fully functional) They share one lead which I assume is ground)

Front of temp gauge:


(Thanks iPhone for the wonky rotation...)

Thanks again to all for the Insights and Advice.

Wes

[gaxdad]

Note: I found British Jaeger on the Smiths Wiki page. So now I know that the gauges are likely just Smiths gauges labeled as Jaeger.

Should I assume that these also require the voltage stabilizer to function properly?

[lumpydog]

Wes - I Emailed you last night but here is more thinking on this and also replies to some of your post here in the forum, for others to see and weigh in as well. Yes, Jaeger and Smiths merged somewhere along the way.

For a 68 truck, It looks like someone has been busy with your gauges! This is pretty common from what I've seen - people like adding gauges to these trucks. For a 1968 NADA truck, the left large gauge appears to have been swapped out with a different model cluster. 68s had two "pods" within that left larger gauge - a "Water Temp" pod and a "Fuel" pod. Yours says "Amps" and "Fuel" - I think it's from an earlier model truck.

Either way, the Fuel "pod" within that cluster (pods were swappable and could be replaced) has the straight-style needle - which is the newer style for negative earth trucks and it should work - but needs 10V (from the Voltage Stabilizer) and also needs to be paired with the correct Fuel Sender in the tank.

Having messed with the fuel gauge and sender in the past, I also found that the fuel sender needs to be grounded. If the tank is well painted - the paint is an insulator and the tank will not be properly grounded to the chassis - so the sender will not be grounded. Mine was like this so I ran a wire directly from one of the circular fuel sender's fixing screws to a screw that penetrated metal on metal into the chassis (I used one of the brake line mounting clamp's fixing screws).

You can test the fuel sender using an Ohm meter - see this post (mine from a long time ago) and the solutions.

The Amp meter is something I have not messed with. If you plan to leave it there, others here will need to chime in!

You can purchase the correct gauge cluster for your model truck here (Note the matching needle type). But that would leave you with a redundant water temp gauge. You could pull the redundant smaller water temp gauge and move the oil pressure gauge to its spot where it belongs and then replace the left over upper small gauge spot with the original ash tray.

Or just leave it all as is and see if you can get all of them running :-)

Your oil pressure gauge is electric and should require 10v as well, from the voltage stabilizer. What is it reading when running?