[updated:LAST EDITED ON 24-Oct-02 AT 08:09 PM (EST)]I recently got my gas gauge back to working by plugging in the correct orange wire (the other one was for non 2 tank systems). Anyway, it quit working after several weeks. A real dissapointment, since all of the other gauges are working.


There is a coil and some other gizmo (Cap or resistor) inline with the ground wire for the gas gauge. I suspect these pieces are not working correctly. I know the coil isn't working since I broke it in half. Anybody know, what is the electrical equivalent of these components? Anybody know where I can get these parts?

FYI: I put 12V straight to the gauge an it maxed out as I would expect. When I shorted the connection at the sending unit, the gauge only goes up a very little. That's why I don't suspect the gauge or the sending unit.

 

I have never seen the components on the ground wire connection. You can just go straight to ground. The gauge has 5v on one side. when you ground the wire to the sending unit, it should make the gauge read full. I don't understand putting 12v straight to the gauge.

 

I figured the gauge to be full at 12V, that's why I tested it that way. The components are inline with the blk wire with a white strip (I assumed to be the ground), The other wire to the gauge is orange and assumed it to be the positive.

I may try to get a picture posted here. This combination of parts doesn't look OEM, but I can't imagine why somebody would have added them.

 

The gauge pegs out at much less than 12 volts, more like around 5 volts if I remember right. If it didn't burn out, you could have tweaked the gauge movement.

Barry

 

[updated:LAST EDITED ON 24-Oct-02 AT 11:08 PM (EST)]It was not operating prior to me putting the 12V to it.

It would move very little, generally between the 0 and 1/4 marks regardless of how much gas was in the tank.

Crap! Took some nice pictures to show you all what I'm looking at and now I can't fine my stupid USB cable. I should never lend out my toys :-(

I will have some pics up soon.

 

[updated:LAST EDITED ON 25-Oct-02 AT 01:32 AM (EST)]More info, since I can't seem to find my USB cable:-(

The gizmos are inline connecting the Black wire with a green stripe and the Black wire with a white stripe that I believe goes to the Gas, oil, and temp gauges.

If all 3 of these are 5v, then I suspect the blk/Grn is from the ignition and the gizmos are dropping the volage to 5V. The side that connected to the grn/Blk wire is labeled IGN on the second gizmo, the "coil" is inline just prior to that.

So, I gather the colored wires go out to the sensor (gas, oil and temp)where a variable voltage drop is observed and then the wire leaving the sensor is grounded.


Without the "coil" inline, my oil and temp gauges are working correctly but the gas gauge is still low. So, maybe it is the sending unit. But, I would still like to know what these gizmos are supposed to be.

 

Well I pulled out the instrument panel on my '68 to understand what you're describing. Don't see it, here's what the gauge circuit looks like on mine.

+12 volts comes in on the yellow/black stripe wire. It connects to the instrument voltage regulator, that rectangular box screwed on the left side of the panel. The connection should be on the outside terminal. The other terminal is the pulsating dc output that goes to all the gauges except the amp. The output connector has two black/white stripe wires coming out, one goes directly to the fuel gauge and the other goes over to pick up the oil and temp. gauge.

There is nothing in-line with the black/white stripe wire(s). This is the pulsating dc supply to all the gauges, not a ground!

I have a hunch you're looking at a noise suppressor choke.

Do your other gauges still seem to be working properly?

My guess about the gas gauge dying is the dual tank switch just needs cleaning. First just try switching it back and forth a couple million times, you should get at least one tank to read. Use a contact cleaner that is safe for plastics, usually they all are. After cleaning mine, not only did it clear up an intermittent problem but it also felt easier to switch with a nice sure click.

Barry

 

[updated:LAST EDITED ON 25-Oct-02 AT 06:05 PM (EST)]here are some pics:

http://www.thedreyerfamily.com/gizmo.htm



I think we are on the same page now: I also believe it is a noise filter (choke) inline with the voltage regulator you described. the other gauges work fine without the choke inline. The gas gauge still reads low. Looks like I can run it without the choke. Maybe my sending unit or the switch went south. I don't know why they would work for 2 weeks then quit.

I am only running the one tank (in cab)now. Maybe I should try to bypass the switch all together. Why is there like 6 wires coming in/out of that switch?

 

Hey nice pics! That is a stock noise suppressor Ford started using sometime in '69. You don't need it for the gauges to work. Unplug it from the instrument voltage regulator and take the wire that was plugged into that choke and directly plug it into the voltage regulator. You should be good to go.

I doubt if your radio will have any noise.

Just a side note, your choke is connected to the correct terminal of the instrument voltage regulator, I have a Ford TSB showing where the factory had screwed up and connected it to the other terminal for awhile. It doesn't work correctly on the load side of the IVR and causes all the gauges to read low.

Barry

 

[updated:LAST EDITED ON 25-Oct-02 AT 06:37 PM (EST)]Done: All gauges working well except the gas gauge. And, I just determined the problem is at the sending unit. Any chance it is the same as the one in the aux tank I removed?


Radio- not an issue: I have the factory AM installed but just for decoration. I'm running a 15GB portable MP3 player to an AMP behind the seat (actually in the seat). Got some 4" seperates in the kick panels (previous owner has already cut holes, so I felt obligated to fill them.

Helpful hint some of you may already know. It is easier to attach the speedo cable at the dash with the cable unhooked at the tranny. Then simply hook the cable at the tranny where it easier to work with.


Thanks for all of the help. I really enjoy the folks on this site. I think it says something about folks that drive old Ford trucks.

 

Hey, glad you got it fixed, or at least know what's wrong with it.

Your gauge problem was bugging me 'cause I thought we had it all figured out. I got off work early yesterday and had to dig into the dash to see what's going on.

We're just a brotherhood of old Ford truck enthusiasts!

Barry

 

>I am only running the one tank (in cab)now. Maybe I should
>try to bypass the switch all together. Why is there like 6
>wires coming in/out of that switch?

I've often wondered why 6 wires too! So with the wife out doing some Christmas shopping, I checked it out.

The 3 wires on the top row of the switch are for switching the tanks. The green wire is the cab tank (in), the green/red stripe wire is the aux. tank (in) and the orange wire is the tank (out) to the gauge.

The 3 black wires on the bottom row of the switch go nowhere! My harness is still taped up but you can feel where the wires come to an end inside.

I can think of a number of reasons why Ford did this but the bottom line is you have a free switch mechanically ganged with the tank switch. Let's see, you could use it to switch fuel pumps, a tank valve and bypass the manual one, a light to tell what tank you're on, or maybe just double-up on the contacts for a redundant switch.

Learn something new about these old trucks everyday!

Barry

(Gtex, don't know if you saw this last post so I'm kicking it back to the top.)

 

Thanks for the info. It will be very helpful when I start trying to put a larger tank in the bed. I may also leave a small tank behind the seat as a reserve, since the switch and plumbing are all there. I'd like to put a small subwoofer back there and maybe still have some storage room.

I can get a 98 Gallon L shaped tank tank at a local truck parts store about $300. But, it does not have a sending unit. I'm hoping I can use one of the ones I have now. To at least provide some idea how much gas is left. I'm tired of filling up every 2 days. Long road trips are not even a consideration at this point.

 

I pulled the sending unit. I'm guessing that the float should not have gas in it? I wonder if I can just buy the float?
Does anybody know of something I could seal this one with that would hold up in the gas tank. It has a small crack.

 

Scrap the old float and get a new one;most all of your after market ford truck sites carry them for around $5.00. I tried the "seal up the old one" trick and it does'nt last long.