Hi, folks. I tore into my 90 740GL in-tank system today.
A few notes:
-I strongly recommend a 5-gallon bucker and lid from home depot for storing the sender if you need to.
-I also strongly recommend a respirator that filters organic vapors - I got one for like $15 at harbor freight and it works great.
-Aluminum foil makes a pretty good cap for the tank if you need one.

Anyway... it's a slight mess inside the sender. There was a leak/split in the top rubber hose (and an attempted patch), an annoying amount of rust, and also a mess with the wiring. I'm here with questions about the wiring.

Does anyone know how the pass-through is designed exactly? 2 of the wires soldered to the passthrough pins snapped off and they're pretty corroded. I wiggled one of them back and forth twice and it snapped off too. Same issue on the fuel level connections. I'm having issues sharing images right now, but I am not sure how these are soldered in. The only thing I can figure is that its a hollow copper/brass tube that the wires were placed inside, then they were filled with solder like in this design - https://i.ebayimg.com/images/g/UlkAAOSwCUJhf0D8/s-l1600.webp

If that's the case, it's going to be tough to get them hot enough, but I'll be able to replace the wiring quite easily. Can anyone confirm this is their design too? Or something else?

Thanks in advance and happy bricking!
Will

I've got this pretty well figured out. I want to do a write-up for the FAQ on it, but until then I think that you can use this if you end up in my situation:

1 foot of 1/4inch SAE 30R10 grade fuel line, which is rated for submersion in fuel. Most line can only tolerate fuel on the inside.
Gates: Part# 27087 Product# 42190014 - 1/4" X 10 FT SUBMERSIBLE FUEL LINE

TFFN wire - 18awg should work. Be sure to keep the clear jacket intact. This is a flexible version of THHN wire. TFFN is Flexible Fixture wire while THHN is High Heat wire.

I think I will be able to remove the solder by first cleaning the corrosion off and using a cheap 25-30 watt Harbor Freight soldering iron. We'll see how that works.

Heating anything that has been exposed to hydrocarbons may be VERY DANGEROUS!

Dried gunk deposited on the item may be vaporized by heat and cause an explosion.

I have seen a picture of three firefighters engulfed in flames when they tried to cut an empty oil drum with a K12 saw (a disc saw which generates heat and sparks)

Any hydrocarbon heated enough can produce vapors that can be explosive - for instance grease, and even coal. Coal and oil furnaces do not have a secure latch, just a short hook, so that they can blow open if there is an explosion.

Putting tin foil over an opening in a gas tank may be OK to keep vapors in, but if you drive the car, fuel sloshing may pop the tin foil off or burst the foil

Thanks for your warnings.

The aluminum is just to keep the vapor level low while the entire sending unit is out of the car. I'm not suggesting anyone use it for more than a temporary cover. It's just much better than a big gaping hole into the fuel tank. I pumped all the other fuel into proper gas cans.


Yes, cutting into and sparks inside closed vapor-filled containers is especially dangerous. Hydrocarbons can soak into the metal and seep out for a very long time. The only right way to do that is to thoroughly clean it and at the final step to keep it filled with water, which becomes difficult when it starts to leak out.

No flames will be involved with this, but this will require a soldering iron at or around 600F. It's essential to let the parts evaporate for days until there is no smell of gasoline or other solvents.


I have a story about all hydrocarbons being flammable... I once bought some tea lights from Kroger that had plastic cups instead of the usual aluminum. The cup itself caught on fire with one of them!