hello sl6 sages - fuel gauge dropped to dead empty when i know there is plenty of gas in car. i know there are 3 items, the gauge, the tank sending unit and the voltage limiter that could cause a crapout. usually i recall it is the sending unit. car is a well used 76 feather duster sl6. forget how to distinguish which part has gone too hell. if you take the wire off the tank unit ground it and the gauge moves to full, i surmise that would indicate the limiter and the gauge are ok and the sending unit has gone to hell. is my analysis correct? never had to replace a gauge or a limiter but have replaced the sending units in other mopars. if it is the sending unit im betting they are mighty tough and expensive to get. how about your best advice and recommendation? thanks tons paladin

Sounds like a sending unit to me...
Take it out and have a look, could be a loose wire or something simple...

See:

http://www.vernco.com/sparks/id697.htm

for a writeup on how to fix sending units.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

If the temp guage reads correctly, the voltage regulator is most likely ok. If you ground the wire at the sending unit, and the guage goes to full (do not leave the wire grounded), the guage is ok. That leaves the sending unit, or a bad ground at the tank. As far as the sending unit, it might be a float with a hole in it. These floats are available from your friendly Ford parts person.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I'm preparing the fix this same problem on Sunday. If I have to actual replace the float, it looks like the entire tank needs to be dropped out. I am concerned about causing a leak between the filler tube and tank as I have NEVER worked on something like this before. Also, the FSM refers to a fuel sending unit gasket, that it says to replace. I can't find a place that has this gasket to save my life. Should I just find some gasket material and make one?

I also read about a special "gauge" tester for the fuel sending unit. Mine reads empty all the time. Basically if I ground it (key on) it should move to F if the sender is still good if I'm understanding Charrlie right. I just dont want to short the sending unit out by accident and then be really SOL.

Anyone have some tips to share?

Thanks!

MJ

update--pulled the blue sending unit wire and found that the gauge would creep up slowly when I jumpered it to ground. I also was searching for the ground wire that is supposed to be strapped to the sending unit--couldn't find it. I did find a clip that was without a wire, so I tried jumpering between that clip and ground. The gauge didn't creep up at all. I was hoping it was going to be that simple.

Does anyone know where the heck that ground wire is supposed to be? I have very little space there without dropping the tank down. Can I just loosen the tank a little bit to gain about 2" more of working room without damaging the filler neck? Or should I unbolt the filler neck before trying to do anything with lowering the tank?

Thanks in advance

MJ

Run a ground wire from the trunk thru the same hole that the sending unit wire goes thru.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

ok i'll look for that...the wire for my sending unit was underneath the floor of the trunk wedged up on the right side. I never checked to see where it tracked back through to. Thanks!

MJ

update 2--

When looking from the top through the hole the sending unit wire usually takes up, I can see the tube of the sending unit is physically strapped to the body of the car. I presume that is how its grounded, not by a wire. So my likely suspect is the float. Again, any tips for getting at the sending unit without dropping the entire tank is more than welcome!

MJ

Are you talking about the 5" piece of metal that's on the hose that connects the sending unit to the main fuel line............

I'm not sure I'd trust that.

Maybe add a ground wire to the metal sending unit tube with a hose clamp for at least testing purposes.


Supposedly, you can wiggle out the sending unit without dropping the tank. I'm not so sure about that after adding a electrical fuel pump back there to prime the system for easier starts. There maybe more room if you support the rear end up with the frame and let the axle drop rather than support from the axle....

And make sure the tank is almost empty before you try......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

ill try lifting the frame and see what I can get to. As it is now, I can't even see the bolts that hold the sending unit in. I'll see if I can get a small hose clamp around the sending unit--its a darn tight fit. But certainly not harder than dropping the entire tank!

Thanks! I'll post back any progress. The tank has some surface rust anyway, so if I drop it i'll get rid of that and paint it. I just don't want to mess up any of the connections and develop leaks.

MJ

That's because there aren't any bolts......

You need a brass punch (don't want any sparks....) to loosen the ring that holds it in

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Well I found the problem. At first I was ecstatic. I dropped the tank part way, and was able to extract the sending unit. As I watched it slide out, I saw that the float was completely missing from the wire. Eureka! I did a little happy dance under the car (while on my back) and thought life was good. Of course, as with any of my repairs, its NEVER that easy

Upon complete removal of the sending unit, I noticed it looked pretty rusty. Then I tried to move the float arm...it had some resistance. THEN the really bad stuff happened--I made the mistake of looking at the internals. Apparently the car must have sat for a VERY long time without much gas in it, because the entire sending unit is rusted up good. Peering into the internals, I noticed something that gave me pause--the electrical pickup the float arm is supposed to move against seemed a bit out of place. Closer inspection revealed it wasn't attached at all, and a slight shaking produced a most disheartening result--it simply fell out in two pieces. Which now means I am the proud owner of a totally non-functional 62 fuel sending unit.

Never to be completely foiled, I pulled out a 67 sending unit that I recently acquired for just this eventuality. I found it to be fairly different, so I need some help deciding whether I should try and retrofit this 67 piece with parts from my 62, or try and find a replacement for my 62. I don't think there is any hope of ressucitating my current 62 unit. Will I live forever without knowing if I'm about to run out of gas?

So please, help me figure this out! There are 3 problems I've spotted so far:

• 1--The length and angles of the float arm and pickup tube are quite different
  
  2--Removing the float arm and pickup tube from my 62 and placing them in the 67 could result in failure of certain parts
  
  3--(And most importantly) The width of the "sweep" on the 62 and 67 units are somewhat different. The 62 has a bent float arm while the 67's is straight more or less. Is this going to foil me before I even begin?
  
  Here's a few small versions of my problem:
  
  
  Side by sides of the arms and pickups
  Different range for the float arm
  
  Different placement of the electrical contacts inside the units
  
  
  Corrosion on the 62:
  Clamp I need to work on without breaking:

napaparts.com or checkers.com may have the sending unit or some stores in the hemmings
magazine may have it also. getting a new one may be easier than trying to fix the original.

yeah I tried both of those places first, and neither had it. I'll check hemmings as well