73' Duster fuel sending unit replacement

[JjyKs]

After winter I noticed that my tank was almost empty. Went to fill the car up but it stayed at low level. There is a small jump on the fuel level when I turn ignition on, so the gauge itself (which is some aftermarket autogauge one) seems to atleast move.

I haven't worked with fuel sending units before and for some reason it was pretty hard to find information on how to diagnose it in a body cars.

So if we make an assumption that the tank and sender unit are stock parts, and only aftermarket thing is the gauge itself, what I should be able to measure from the cables coming to the gauge? I suppose that there's a variable resistance? What it should be with full/empty tank?

If it comes down to the sending unit replacement, what kind of procedure it is? Is it doable on jackstands? Should the fuel tank be completely empty?

 

[Ricks70Duster340]

After winter I noticed that my tank was almost empty. Went to fill the car up but it stayed at low level. There is a small jump on the fuel level when I turn ignition on, so the cauge itself (which is some aftermarket autocauge one) seems to atleast move.

I haven't worked with fuel sending units before and for some reason it was pretty hard to find information on how to diagnose it in a body cars.

So if we make an assumption that the tank and sender unit are stock parts, and only aftermarket thing is the cauge itself, what I should be able to measure from the cables coming to the cauge? I suppose that there's a variable resistance? What it should be with full/empty tank?

If it comes down to the sending unit replacement, what kind of procedure it is? Is it doable on jackstands? Should the fuel tank be completely empty?

On my '70 Duster, I was able to R&R the sending unit without pulling the tank. You will want to remove all the fuel from the tank you can before pulling it so you don't get baptized!

 

[CRUZE 418]

What's a cauge? There are so many threads on sending units and gauges that my head is spinning.

 

[Ricks70Duster340]

What's a cauge? There are so many threads on sending units and gauges that my head is spinning.

Think it was a typo, should be "gauge"!

 

[diymirage]

Not sure what the sending unit should read, but I see two issues here...both stemming from the original sending unit design

As you mentioned, it is not a linear signal
(Which makes sense since the tank is not "even")

I can't imagine that a aftermarket "cauge" would match that

BUT if it does, and the sender is bad, you probably will not find a good new one, since all the new ones are linear


Now, when you pull it out, I've found less then 1/2 is doable (on my 71 duster) but less is always better

Make sure you hold on to the stock locking ring too, the new ones are thinner and simply don't seal well

 

[66fyssh]

Now, when you pull it out, I've found less then 1/2 is doable (on my 71 duster) but less is always better

Yes, 1/2 tank or a little less should be low enough. Best to use a brass drift to loosen the lock ring if you don't have the correct spanner wrench. Don't want any sparks back there...just in case.

If you want it as accurate as possible, have your original unit rebuilt. A search on FABO should come up with a couple of companies. Not real cheap though.
If you decide to go with an aftermarket sending unit, post up your old one for sale here. Someone will want it.

 

[66fyssh]

Just noticed the OP is from Finland. Other than one word, his English is better than mine, lol.

You must stand out driving a Duster over there!

 

[JjyKs]

What's a cauge? There are so many threads on sending units and gauges that my head is spinning.

Yea that was a typo. Meant gauge

Yes, 1/2 tank or a little less should be low enough. Best to use a brass drift to loosen the lock ring if you don't have the correct spanner wrench. Don't want any sparks back there...just in case.

If you want it as accurate as possible, have your original unit rebuilt. A search on FABO should come up with a couple of companies. Not real cheap though.
If you decide to go with an aftermarket sending unit, post up your old one for sale here. Someone will want it.

Well to be honest only things I care about is that full tank shows full and I have enough gas to drive to gas station when it shows 1/4 I wouldn't be surprised if it didn't have an original part, but I'll have to check it. Even the locked differential is from a ******* Toyota Hiace

Not sure what the sending unit should read, but I see two issues here...both stemming from the original sending unit design

As you mentioned, it is not a linear signal
(Which makes sense since the tank is not "even")

I can't imagine that a aftermarket "cauge" would match that

BUT if it does, and the sender is bad, you probably will not find a good new one, since all the new ones are linear


Now, when you pull it out, I've found less then 1/2 is doable (on my 71 duster) but less is always better

Make sure you hold on to the stock locking ring too, the new ones are thinner and simply don't seal well

Hmm, I always felt that the fuel level didn't go down linearly. And the last half seemed to last for a much less time than the first half. I'll have to burn some fuel and grab that thing out

Just noticed the OP is from Finland. Other than one word, his English is better than mine, lol.

You must stand out driving a Duster over there!

There's actually quite healthy american car culture in here. But yeah, people always seem very excited when they see my car