Recomnditioning Fuel Sending unit

[joetiii]

This might seem stupid, but how many have had luck w/ reconditioning their fuel senders?

I just had a rusty tank replaced and the sender still reads high by 6 gals. I'm hoping to "clean" the sender and have it record a more accurate level.

Am I high on 93 octane? or have you guys had luck getting the rust out of old senders and got them back recording levels correct?

[Evans, Marv]

I tried it, and didn't have much luck. There is a writeup somewhere about how to do it. Mine didn't work out well, so I didn't fight with it, especially when I found out a good used or new sender is pretty cheap.

[Argo]

Here's the thread. I just replaced mine because, as Marv said, they're pretty cheap.

Can I clean a Fuel Gauge Sending unit?

Argo
88 Targa

[Early_S_Man]

Joe,

It can be done, I did it, ... Bruce Anderson did it at Le Mans one year for his 935 Moby ...

1. Remove connector, five nuts, then extract sender from tank ... dry outdoors if still wet with fuel.

2. Remove the tiny nut at the bottom of the cylinder, then remove cover.

3. Using a Faber ink-type stick eraser ... burnish the nichrome wires up and down to remove any corrosion deposits causing the float to stick or bind.

4. If the contact sliders are loose on the wires, retension with small needle-nose pliers.

[daepp]

Not to hijack - but has anyone had any luck with shortening their sender? The reason I ask is that the prior owner had the tank resealed and these's a build up of resin or epoxy under where my sender goes. It sticks up about 1/2 of an inch.

[randywebb]

what? no vinegar?

[wholberg]

I took mine apart and cleaned it in a manner similar to what Early S Man described, and it has worked like new for 10K miles. Before I cleaned it, it would not read below 1/2 tank. I did find some seemingly insignificant deposits on the wires and float, but taking it off made all the difference.

[daepp]

Guys - is there room withr espect to the inside components to shorten the sender housing by approx 3/8"?

[wholberg]

Originally posted by daepp
Guys - is there room withr espect to the inside components to shorten the sender housing by approx 3/8"?

The sender I took out of my car could not be realistically shortened. It would be easier to figure out some way to replace it with a different type.

[Early_S_Man]

Daepp,

It is possible, but there are a couple of considerations that make it not such a simple job ...

It has been 20+ years since I had mine apart, so I am not sure whether the struts that hold the two end plates in place can be shortened , or if they would have to be replaced with shorter fabricated replacements.

The resistance elements -- the nichrome slidewires -- can either be clipped and resoldered, or wound up on a wooden matchstick and epoxied to the bottom plate with microballoons to thicken and strengthen the 'patch' job. Either type of alteration will result in inaccuracy in the lower level tank readings.

The cylindrical cover would have to be shortened, but it is thin aluminum, so an X-acto razor saw or Dremel cut-off wheel could easily do the job.

[joetiii]

I'm not sure that I'll find smutz in this unit. The guage doesn't get stuck. It just goes full to empty in 180 miles and I can put only 10 gallons back in.

it seems easy enough to pull out and check so we'll see what we can do.

['78 SC]

In my case the sender was erratic because of deposits (varnish?) built up on the various contacts and the two sensor wires. I found lacquer thinner dissolved the deposits easily. Work carefully, the wires are delicate and need to remain taut. I used a q-tip and a light touch. Our host carries replacement gaskets.

[daepp]

Had this spacer made to deal with sender-to-tank depth issue:

Got everything sealed up very well now - and the guage no longer reads above 1/3 full. Oh the shame!

Not sure if i clogged an upper hole (a vent?) that's in the cylindrical side of the sender near the top. If this hole is too high now it will vent into the tank. Not sure how the prior owner made the guage function without venting into the trunk.

[Jay Auskin]

David, there's a hole on the top and bottom. Make sure the sealant for the spacer didn't seal the top hole. Otherwise, there are two thin wires in the middle, and a float. The float can be binding up on the wires. It's easy to take apart. A few tabs on the bottom, and slide the outer tube off.

[daepp]

Thanks for the info Jay.

So is the hole in question in the side of the sender near the top or on top of the sender (I should get new gaskets Thursday so I can't look until then). And how did your seal deal with that hole?

[Jay Auskin]

David, I don't believe the I.D. of the seal hugs the O.D. of the tube. It's been a few years, so I can't quite remember. The upper hole will be clear when the sender is removed, just test fit the gasket. Also, turn the sender over and back a few times to make sure the "float" is moving ok up and down the wires. As to your venting into the tank question, yes, I believe that's all it does. The tank isn't under any pressure to my knowledge.