Fuel tank sender repair.

[TonyK]

For those that like the challenge it is possible to repair the fuel tank sender resistor by rewinding it.

From ebay I located 30' of 38 guage Nichrome wire. Resistance is 43 ohms per foot. You need about 10 feet. $5 for 30 feet of wire.

First step with the sender removed is to pry up on the tab that keeps the sender body connected to the mounting base.

Here is what you will need to do the repair. My tired eyes need a 5X magnifier that straps to my head to see this fine detail. Jacobs on Line supplied the wire for the repair.




The sender resistor slips out of the body and you can see the broken part.



Next I needed a crimp to make the connection to the body of the resistor. OEM uses a crimp, no solder is used to make the connection. Take a crimp and open it up like this.




The eye will be cut off but the open part of the crimp is used to go around the stake on the resistor body.

Start at the wire terminal connection of the resistor body and push the new wire through the rivit then wrap several turns around the stake connector. Use the expanded crimp to hold the new wire against the wire stake, crimp to make connection. Now with the body mounted in a small vise start winding. The edges of the resistor body have notches for the wire to be wound into and prevent it from slipping down the resistor body. The wire only .038" is very strong and can be pulled to keep tension on it.





When at the end several wraps that loop under are required to terminate the nichrome wire. The body of the sender will captivate the end of the wire when inserted. Slide back into the sender body.





Do a resistance check and low fuel light check. You should have about 400 ohm reading when the tank is low and about 8 ohms when the tank

is full.


TonyK.

Grimsby Ontario Canada.

 

[bbrown]

I'm impressed Tony,

Great job. I never would have gone through it.
I give you credit for crafting up the repair.
I've already replaced one on a gas tank by exchanging the element from another old (NOS) fiat part, just so happened to be the same thing.

This means you know what the count of turns is on the winding that make up the total resistance. :grin:

This makes you the official gas tank sender re-winder! :excited:

 

[strangepod]

Nice job Tony - I think you might have a side business there!

 

[TonyK]

Thanks Bob...

Great job. I never would have gone through it.
I give you credit for crafting up the repair.
I've already replaced one on a gas tank by exchanging the element from another old (NOS) fiat part, just so happened to be the same thing.

This means you know what the count of turns is on the winding that make up the total resistance. :grin:

This makes you the official gas tank sender re-winder! :excited:

Just a few more points about this. The stock sender wire is 37 guage and is 43 ohms per foot. The replacement wire is #38 guage and 45 ohms per foot. There is difference of 2 less windings making it 93 in total. the difference in wire thickness is .0005" smaller. The resistance is about 10 ohms lower, but all that means is that the needle doesn't burry it's self into the stop before the low fuel light comes on. For $5 of materials it was worth the effort.

Just apoint about all you guys that trailer. This happened on my car when I was on the way to FFO 2011. I only had half a tank of gas and all that bouncing on the trailer added to the wearing out of the sender. This is the second sender in my car since new and it now has 54K miles on it. Next time I trailer I will fill the tank on the car to limit the amount of motion in the fuel tank and on the float arm.

When I was doing this I was using a 5X magnifier with a focal length of 4 inches. Meaning... I had to have my head 4" from the work I was doing. At 20 turns I was about ready to toss the whole prodject but kept at it stiff fingers, neck, back and all that I didn't mention.


TonyK.

Grimsby Ontario Canada.

 

[strangepod]

I see a winding jig in your future!:jedi:

 

[Black-Tooth]

Again TK, you have my admiration...

I, many moons ago came across a similar situation, finding the resister wire WORN through and broken in the middle.

I carefully unwrapped it a bit, rewound it so I had a bit of slack... and TWISTED it back together on the backside, opposite the wiper. As you stated, it would not take solder!

This worked for may more years and may have been somewhat inaccurate, but not that I could detect from the driver's seat. The second time it failed I bought a new one. I never woulda thought one could actually BUY that kind of resistance wire! Kudos to you!

 

[Jim Young]

I did the same patch Tony,,

Quite a few years ago. I wondered then if the wire was available and what type. I have a spare sender now , and like to tinker and fix also , at least I used to. Wellcome back Tony also. Good job Tony K. on tracking down the proper wire,:clap::clap: I'll mark it down for future.

 

[budgetzagato]

Awesome!

15 years ago I attempted a similar repair on my 850 Spider. Couldn't find the needed wire to save my life. This is before the internet was everywhere. Ended up rewinding mine with what was left unbroken on my sender. Worked ok, just went from 1/4 tank to warning light awfully quickly.

 

[Black-Tooth]

Hey Jim...

Thanks for the kind words... and yes... I try to fix EVERYTHING before I screw it up totally and then throw it out! I'm usually somewhat successful though. Just my nature...

And by nature... I guess I mean a genetic flaw... as my Dad did the same so it was either by his example or genetics... but none of my kids seemed to pick up the trend either by genetics or by example. HA!

 

[CandBMotorworks]

Tony K...

I'm about to do this myself (have to order the wire from Jacobs first). Your finished product looks nice. I have a bunch of questions and hope you'll indulge me.

First, is there any reason I couldn't just drill out the existing rivet and install a new rivet?

Next, I note in your finished product photo that there does seem to be some variance in gap between the wires, particularly on the starting end. I presume that for our purposes that won't make much of a difference?

You said that it was 93 wraps from end to end. Is that just how it works out or is there math involved to make the gauge work correctly?

You're wrapping around a pale colored bridge, whereas mine is dark brown (as it the plastic case). I'm not sure which is better as far as visibility is concerned. I felt the bridge edges but really couldn't feel the grooves you referenced. I also couldn't see them, even under a magnifying glass. Were you really able to see them as you did the wrapping?

Any tricks to offer while trying to wrap, in terms of keeping the wire tight as you go?

Last question: Once rebuilt, how tight to the resistor wire should the armature be? I ask because when I took mine apart you could see the area where the armature had rubbed through the wire and into the plastic bridge a bit.

Thanks!

 

[TonyK]

Answers

No issue drilling out the rivet, but I didn't have brass rivet or rivet eye setting tool. I would not use an aluminum rivet because over time it will corrode and you will have a bad connection.

The end where the gap is larger is when the tank is full, so it really doesn't matter.

I counted the wraps of the wire before I took it off of the sender bridge body. There is a bit of math if you consider that the former is about 1" of wire per wrap or turn if you now measure the resistance of a length of new wire that is 93" long and the value is either 10% higher or lower than 400 ohms then you will have to either add turns or subtract turns to obtain a closer gauge reading of how much fuel you have in the fuel tank.

I have never wrapped a dark bridge so I can't comment on how much easier or more difficult it will be to wrap. The important thing about wrapping to the bridge is to have the wire already wound on the card that it comes with. The wire is too thin to be able to wind by just using your fingers to tension it. The lines were in the bridge face and sides and realize that the stand magnifier shown in the picture has a band around it's base that I put around my head. I was working only about 3" from the bridge as I wound it. The bridge was held in a small model makers vise. If you ordered the same wire as I did then you should not have an issue with doing this repair. It takes time and once you start if you need to stop put some tape around the bridge and card that has the wire on it to stop it from unwinding. As for tightness, the tighter the better as it stops the growler from moving the wire on the bridge, if the wire flexes on the bridge it will in time break. Remember the fuel is constantly sloshing around in the tank and moving the float, which rubs or flexes the wire and could bend then break a loose wound wire.

Let me know how you make out?

TonyK.

Grimsby Ontario Canada

 

[CandBMotorworks]

Thanks

I ordered the 38 gauge wire from Jacobs. It seems to be the only place you can find it. How did you know that the original was 37 gauge? I have nothing that measures that small in my shop.

Also, doing the math (93 turns at a little over 1" per turn) it looked like 10' would be sufficient, so I only ordered 10 instead of 30. I probably won't be able to get to this project until next weekend -- depending upon when the wire arrives.

I don't have a brass rivet either and can't seem to find them at any of the local hardware stores. I take it that your metal crimp is NOT aluminum? Unless it's stainless, I imagine it will corrode as much as the aluminum.

I have another issue -- the filter sock was deteriorating so I removed it. I've been looking around for a suitable replacement. It appears that the tube is about 5/16" in diameter and I've found some online that are listed with that diameter inlet. The one that I found has a metal ring that slides over the tube, but I don't see any way to crimp it. The old one had a large ring that was crimped in four places. BTW, the application for the one I've found is MOPAR, as I recall.

If it works I'll try to post a pic and info for others.

 

[TonyK]

More answers

The original wire I used a micrometer and it measured .0045" if you go to the pocket reference and look up wire gauge size American Wire gauge, which at one time was Brown and Sharp it states that 38 gauge wire is .004" and 37 gauge wire is .0045".

The crimp is tinned copper electrical grade and since brass is made from copper and tin it should be okay to use inside the tank. The wire going to the mounting flange is copper and it is always in the fuel. Gas today has ethanol which attracts moisture. Aluminum with water and gasoline will corrode over time, it will get a white powder forming on it and the connection will be lost.

Stainless is a poor electrical conductor, even worst than steel. Stainless will not corrode in fuel applications.

Post the picture of the sock, possibly I or others can suggest a fix.

TonyK.

Grimsby Ontario Canada.

 

[CandBMotorworks]

Re Sock

Mine crumbled to pieces and is in the trash.

If you are talking about the one I'm thinking about using, though, here's a link to it:

Fuel Pickup Sock

Aside from ensuring that it fits tight enough not to slip off, my other concern is that it won't collapse and cause fuel starvation. The stock one (I'm assuming it was stock) was quite thick having multiple layers of the material. It was like they took a large piece of loosely woven material, folded over into several layers, wrapped and then clamped it to the tube.

Re the gauge -- I thought I had a micrometer but couldn't find it anywhere. Even if I had measured the diameter, though, I would have had to look up on the interwebs to find a conversion to know what gauge it was. Which is why I'm glad you've already done all the "heavy lifting" for this project!

Re: White powder -- the pickup tube and flange at the top are coated in some type of protective coating -- I want to say nickel. But it has worn in places and I have white spots on the tube and most of the underside of the flange (which makes sense as that's where the condensation would collect when the tank wasn't full). I thought about sending it out to be retreated. Do you think that's worthwhile?

Also, the return tube (plastic) is hard. I'm wondering if I should replace it. The way I look at it, I can do all of these things now while I have it out, or do only part of them and then have the thing fail on me sooner. Did you replace the return tube on yours? If so, where did you get the tubing?

Again, thanks for all of your help on this.

 

[TonyK]

Ear clamps.

See this link.

http://www.google.ca/search?q=ear+c...NO-rw0gHHsZzcCg&ved=0CDUQsAQ&biw=1205&bih=489

The sock looks okay, I would just use an ear clamp to hold it in place on the pick up tube.

I never replaced the return line, I just left it as it was. As for the size of the sock, you should be okay, heck that sock is off of a pickup truck with a bigger engine than the X ever had, I don't think you will have a problem. As for removing the sender as long as the tank is half full or less I have changed it on the car without issue.

Currently I am restoring a Mazda RX7 1985 I have patched and welded the tank a few years ago. Now that it is off of the car I am going to use EastWood's gas tank reconditioner/ sealer. Eastwood sells some very good products and stands behind their products.

See this link

http://www.eastwood.com/gas-tank-sealer-kits.html

Give this all some thought.

TonyK.

Grimsby Ontario Canada

 

[CandBMotorworks]

Follow Up

So, I got the wire, the sock and a float. Someone had posted a link to an ebay seller who had a float for a Jeep application that looked similar to that used in the FIAT. It was cheap, so I ordered it to try it out. Here is a crappy cell phone photo of the new one and stock one next to each other:

As you can see the new one is about 1/4" longer than the old. I don't know if this will create an issue or not. But the bigger question I have is which way does the float face?

I'm also starting to struggle to remember how the sender fit into the tank -- by which I mean, where are the tubes located and wire connectors located on the face when it is installed correctly?

I have to do the winding still and put the whole thing back together.

The sock -- it was longer than I expected it to be, but fit over the pickup tube o.k. The metal ring that slips around the pickup tube is dished, so it doesn't look like I'll be able to clamp it. I might be able to clamp behind it over the sock. It may not be necessary, anyway, because it's about 3" from the end of the tube and I don't know that it would ever slip off.

 

[strangepod]

My bigger question is how is the sending unit clocked? I removed mine (from my 87) and like a stupid person, forgot to mark it..

 

[jvandyke]

There was a thread on this not too long ago.....

 

[CandBMotorworks]

O.K. rheostat is re-wound...

I've put it back together. Tomorrow I will take it up to my friend's house and put it back into the car. Then check to see how well I did. While I'm not certain about the accuracy resulting from my windings, it will certainly be a lot better than the all or nothing results I had previously.

Cross your fingers.

 

[Black-Tooth]

Jeff... before you install it...

Test it OUTSIDE the tank!

Usually the leads will connect and then just use test clips or some wire and GROUND the unit to the chassis.

Then move the float arm up and down and peer through the rear window at the gauge with the key ON. Also insure the low gas light works as well.

Hope all works well for ya!