1990 Legacy wagon - flaky fuel gauge

[Hondasucks]

my 1990 Legacy has a flaky fuel gauge, it reads full when the tank is full, drops pretty rapidly to 1/2 tank (in about 90-100 miles) and from there it will drop to E, where it will stay for another 100 miles or so, then it will register about 1/8 tank, and drop normally from there. I took the sending unit out and tested it and I am pretty sure it is bad, however when I went online to order one, the only place I found one was www.1stsubaruparts.com and for the 4WD models it lists a main sending unit and a sub sending unit, both the same price. My main concern is which sending unit is which? I assume either the sub unit is for the low fuel light (which works correctly) or since the tank is a saddle tank, it has a sending unit on each side. The one that I removed was on the driver's side of the tank, has one electrical connector and one hose on it.

[Legacy777]

There's two senders, one for each side of the tank.

There is a connector that goes from the sub unit to the main unit. The wiring combines and goes to the fuel pump connector under the seat.

What you need to do is pull the access panels, and do some testing between the sub unit, main unit, and fuel pump connector to isolate each circuit.

In this scan you can see what's going on, and sort of what you need to do to isolate/test each unit.
http://www.main.experiencetherave.com:8 ... r_scan.jpg

I say this because I was not able to get test connectors on the sending units. You may be able to since you have a wagon.

I'd venture to say the main unit is bad, and not the sub unit, but you can easily pull them out, move the level arm, and measure the resistance.

[Hondasucks]

Okay well it was the sub unit that I pulled out since it only had two wires going to it. The resistance was pretty flaky when I measured it, but I don't know if my dad was making a good connection or not since he was holding the meter leads and I was working the arm lol, I'll pull them both out and check them this evening, hopefully just one of them is bad, they're $64.76 from 1stsubaruparts.com, and I could not find them at the auto parts store