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Replacing fuel level sending unit?

  • Thread starter Thread starter luvmy40
  • Start date Start date
L

luvmy40

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So, I did a search for this but keep getting a fatal error message.


Are the fuel level sending units available new anywhere?

If not, has anybody had any luck with used ones from ebay?

Mine has several dead spots and the wiper is making good contact the entire sweep. The readings will go from a few kohm to a few Mohm and then over limit(open) and then back to a reasonable reading several in different areas.

The gauge was stopping around 2/3tank but I was hitting the reserve.
 
Are you referring to the gas gauge in the instrument cluster or the actual unit that goes into the gas tank?
 
Calibrate the sending unit.

Leave the cover off the unit and put it back in the tank ( wont hurt leaving cover off for now).

Next find the tanks capacity WITH RESERVE and get half that amount in a gas can. Use the half tank amount because there IS a mark at half full on the gauge. You want the needle to line up with the half full mark when done.

Now put the gas in and turn on the key and WAIT for a full minute for the gauge to settle.

If the needle is offthe 1/2 tank mark, use this formula to bend the sending units float arm till its good.

IF THE NEEDLE READS LOWER THAN 1/2 TANK, BEND THE ARM DOWN

IF IT READS HIGHER THAN 1/2, THEN BEND IT UP.

You may have to do this a few times till you get the needle to settle at the 1/2 tank mark. Just use PRIme to drain down the tank and tweak the arm again. Once your satisfied, put the cover back on the unit and reinstall. Now you should find you have to hit reserve around 1/8 tank or so.
 
After calibration if it still isn't working then replace..

AND I always bend the slider a bit to be positive it has real good solid contact with the coils. Move the arm up and down to see that its not coming off the coils with the slop that's in the lifting arm. That arm does move a bit in the holes on the assembly..thats why I bend the slider a little. So it doesn't "skip" like you said.
 
chuck hahn said:
Calibrate the sending unit.
Click to expand...

Calibration won't fix dead spots.

Many don't care much about the fuel gauge option until their fuel gauge stops working and they run out of gas, then they realize just how much they value it. ;)
 
I think the slider is loosing contact as the arm moves..thats why I said to bend the slider and be positive that it will never loose contact.

It makes no sense theres a "dead spot" because its all one continuous coiled wire. If that wire had a break or "dead spot" anywhere there wouldn't be continuity thru it anywhere for the wires to carry the signal to the fuel gauge in the dash at ANY level of fuel in the tank.
 
I'll take another look at the sending unit but, I put pressure on the wiper arm against the coil and it still jumps all over the place when run through the range of motion.

I agree that it should either give a reading or be open, but that's just not happening here. It's pretty well corroded so I may just take a chance on a fleabay replacement anyway. I will calibrate it when I get one to read consistently.

Thanks
 
Found the problem!

The piece that completes the ground from the wiper arm armature to the frame of the sending unit was badly corroded and had no spring tension what so ever. I tried to clean it up and re-tension it but that was a no go, so I soldered a short piece of wire from the armature to the frame and it works perfectly.

Now to find a new gasket.

I ordered a gallon of Evpo-Rust from Tractor Supply today.

Has anyone used Caswells tank sealer? I have bad luck with Kreem in the past and the POR 15 doesn't seem to have any better reviews.
 
So now you can still fine tune the reading as I described in the calibration process. They weren't all that accurate from the factory. Heck, my 78 1000C was almost an 1/8 of a tank reading high...so it surely wont hurt if you want to be sure of the reading being accurate.
 
luvmy40 said:
Found the problem!

The piece that completes the ground from the wiper arm armature to the frame of the sending unit was badly corroded and had no spring tension what so ever. I tried to clean it up and re-tension it but that was a no go, so I soldered a short piece of wire from the armature to the frame and it works perfectly.

Now to find a new gasket.

I ordered a gallon of Evpo-Rust from Tractor Supply today.

Has anyone used Caswells tank sealer? I have bad luck with Kreem in the past and the POR 15 doesn't seem to have any better reviews.
Click to expand...
Kream is one of the worst products you can buy, pot 15 tank sealer is excellent but if you want to fill pin holes use the caswell
 
Kreemed my 77 750 tank almost 7 years ago Pos and still not so much as 1 problem. That's before I knew of Caswell or POR 15 tank kits.

Kreem is ok but as I keep stressing.....YOU NEED TO CURE IT FOR A GOOD WEEK OUT IN THE DIRECT SUN LIGHT AND GET IT HARD!!!!!!!!!!!!!!!! 24 HRS ISNT LONG ENOUGH REGARDLESS OF WHAT THEIR DIRECTIONS SAY!!!!!!!!!!!!!

Now that I found the Caswell 2 part epoxy liners that all I use. However, I wouldn't hesitate to do a Kreem again.
 
chuck hahn said:
Kreemed my 77 750 tank almost 7 years ago Pos and still not so much as 1 problem. That's before I knew of Caswell or POR 15 tank kits.

Kreem is ok but as I keep stressing.....YOU NEED TO CURE IT FOR A GOOD WEEK OUT IN THE DIRECT SUN LIGHT AND GET IT HARD!!!!!!!!!!!!!!!! 24 HRS ISNT LONG ENOUGH REGARDLESS OF WHAT THEIR DIRECTIONS SAY!!!!!!!!!!!!!

Now that I found the Caswell 2 part epoxy liners that all I use. However, I wouldn't hesitate to do a Kreem again.
Click to expand...

Apparently many people followed the /4 hr instruction
 
chuck hahn said:
Calibrate the sending unit. ... Next find the tanks capacity WITH RESERVE and get half that amount in a gas can. Use the half tank amount because there IS a mark at half full on the gauge. You want the needle to line up with the half full mark when done.
Click to expand...
This is a great idea, but in my garage, I use the white/red transition on the gauge to indicate when I need to switch to REServe. :o

Personally, I don't care how long the gauge stays at (or above) the FULL mark, or even how much is in the tank when the gauge reads 1/2. However, as it reaches the point where I see that I will have to move the petcock, I want to know.

One of our pilots will have to confirm, but I understand that the FAA requires aircraft fuel gauges to be calibrated at ONE point. That point is EMPTY. Apparently they don't care how long the gauge stays at FULL, either, but when it shows EMPTY, you know it's going to be a long, hard walk to the fuel station. :-\\\

I modify Chuck's calibration procedure by running the fuel out of the tank until it stops, with the petcock in the RUN position. I will then bend the float lever to match the white/red transition on the gauge.

.
 
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