Fuel Sender issues

[Legacy777]

This is a continuation sort of from these two posts
http://bbs.legacycentral.org/viewtopic.php?t=24723
http://bbs.legacycentral.org/viewtopic.php?t=26739


I tested the fuel senders today, and the jet pump sender was fine. The main sender put out some weird and semi non-repeatable values. So that's definitely the cause of my weird fuel gauge issues.

I've got the one out of the turbo legacy pump assembly. But I removed that one before....because it too was being weird. When I tested it today.....it had weird readings except when the float was almost near full. So I'm probably going to just buy a new sender unit, so I don't have to mess with this again.

My only concern is that the older style sender unit that is larger is now superceeded to the newer style that has smaller contacts. The issue with that is the smaller contacts can cause more fluctuations.

I did some snooping, and noticed on the 92+ legacies there is some sort of damper or something in the line going to gauge and what not. However I don't really understand what it's doing with how it's wired. Here's the scan....anyone have any ideas?
http://www.main.experiencetherave.com:8 ... iagram.jpg

[vrg3]

Is it possible that when you're comparing "older style" to "newer style" you're actually comparing "FWD" to "AWD?"

Because it seems to me that AWD level senders need to have roughly half the resistance of FWD senders in order to work right, since there are two AWD senders in series.

That "delay amp" appears to only be in line with the thermistor that grounds the reserve warning light. I would guess that it's there just to keep the light from flickering on and off.

Did you check to see if there was any varnish built up on the sender's contacts? It might be hard to see but it could also cause erratic readings.

[Legacy777]

Nope, I'm comparing the older and newer style and not FWD to AWD.

You're correct regarding the AWD & FWD senders. The two AWD senders are in series, and add up to the same resistance as the FWD sender (when full or at the same given fuel level)

It's possible some build up is on that sender, however I just swapped back in that sender around the beginning of January (roughly 1000 miles ago)

I had this "older style" sender in my car from the time I did the AWD & 5spd swap until I did the turbo swap.

When I did the ej22t swap I put in the newer style sender and got weird readings when the tank was low. When I measured the newer sender, the readings I got coincided with the fact that the readings seemed to be normal when the level was high, but were weird when the level was low.

I bought a sender....It was like 65 bucks. I didn't want to yank that damn pump out AGAIN without having a new sender.

I am thinking about draining the gas tank. The 90 & 91 tanks (possibly 92) had drains on the bottom.

Is there anything I can put in the tank to help "clean" it out....