Locating the fuel sender unit on a 1937 Century

[Guest Jon Barker]

Hi guys, can anyone out there help me please. I suspect my fuel sender unit is faulty as the gauge intermittently tells me it's either empty or full and nowhere in between, which is not very useful. Can I get at the unit without dropping the tank ? I'm not sure where to look.

[packick]

Jon:

The sending unit is in the gas tank. The first place I would look, however, is in your trunk. You may be lucky in that maybe a previous owner cut an access hole in the trunk right over the sending unit to access it from the trunk. There should be a plate screwed in over the hole (if there is one).

If there is no access hole, the only way I know of removing/replacing the sending unit is to drop the tank. The hardest part of this job is getting all of the fuel out of the tank. There is a drain plug but I would be real careful unscrewing it since it may be rusted to the tank and you could do more damage to the tank if you use excessive force on it. Sometimes they unscrew with no problems, sometimes not. The only other way to remove the fuel is to syphon it out from the neck.

Once the gas is removed, then it is just a matter of undoing the two strap bolts, removing the rubber grommet around the neck, then dropping the tank out. Depending upon where your exhaust pipe is mounted, you may have to remove its rear clamp to slightly swing it out of the way to allow room for the tank to drop. Be careful when lowering the tank since you don't want to break the sending unit's wire. It should either unplug or unscrew from the sending unit. Once the tank is clear of the car, on top of the tank you will see the screws that hold in the sending unit. Undo these screws and slowly remove the sending unit itself.

Good luck.

Edited October 9, 2013 by packick (see edit history)

[trp3141592]

Hi,

I would add one additional step to Joe's excellent directions.

While you're on your back trying to control the tank and navigate around the exhaust pipe while you snake the filler out of the fender hole and realize that you now need to replace the fender gasket, think about the next time you might have to do this and then do what Buick SHOULD have done. While the tank is out, locate the position of the sending unit on the trunk floor and cut out an access hole so that next time you need to get to the sending unit you don't have to drop the tank. Make a cover plate from 20 gauge or so steel and secure it to the trunk floor with short sheet metal screws and seal the hole with some silicone caulk.

Been there, done that.

--Tom

[Guest Jon Barker]

Joe, thanks very much for the quick response. There is a plate bolted to the floor and I did wonder what that was doing there - I thought it might be an old repair but I think you're right. I'll have a look tonight.

[Guest Jon Barker]

Tom, thanks for the extra information. All these pieces of knowledge are much appreciated as the learning curve for me is a bit steep at times and there aren't too many Buick experts on these islands.

[trp3141592]

Hi,

An additional thought. Most threads that have been discussed here involving erratic sending units have concluded that the problem is a poor connection or intermittent ground (earth) connection at the sending unit. Be sure your wire connections are clean, and consider running a separate ground wire from one of the sending unit screws to a convenient spot on the body or frame.

--Tom