Repairing that awful fuel sender unit

Here's some good repair guides for your Tercel :) Look here for help first!
User avatar
Neu
Highest Ranking Member
Posts: 1191
Joined: Tue Nov 06, 2007 7:59 am
My tercel:: 1985 SR5 No Mods
Location: Hillsboro, Oregon, USA
Contact:

Re: Repairing that awful fuel sender unit

Post by Neu »

So my fuel gauge works pretty well but the top half is mostly useless. It drops from full to about half within 40 miles but from there on out it's pretty accurate. The warning light works fine.

I figured I'd try and clean the contacts real quick and this is what I found.
20210717_131851.jpg
So I may try the ATF or some similar product(Project Farm on YT has tests on it) and then I'll give it a go.
You do not have the required permissions to view the files attached to this post.
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Repairing that awful fuel sender unit

Post by Petros »

clean out the philip recess in the screw heads real good, and after the ATF soak, they usually will come out if you use a new philips tip (that is not worn). if not, you can try wrapping them with a hammer to see that will break it lose. at worst, you can drill out just the head, and use some good vise grips to unwind the shank left behind after you get the sender off.

good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
The Professor
Highest Ranking Member
Posts: 650
Joined: Wed May 12, 2010 6:38 pm
My tercel:: 1987 Tercel SR5 4WD wagon
Location: Western Washington
Contact:

Re: Repairing that awful fuel sender unit

Post by The Professor »

First, use some form of penetrating oil. Find a phillips socket and use a ratcheting wrench to remove the bolts. This allows you to put WAY more downward force onto the phillips bit, preventing it from ramping out of the bolt head. Plus, a lot more torque can be applied versus a normal screwdriver. If you have any valve lapping compound, apply some to the tip of the bit to help it bite into the bolt head (I bought some from the local auto parts store specifically for this purpose).
1975 Subaru SuperStar wagon
1984 Subaru Turbo-Traction wagon & hardtop
1987 Subaru RX 3-door
1987 Subaru RX Type-RA 3-door
1987 Toyota Tercel SR5 wagon
1999 Subaru Forester S
2002 Subaru WRX sedan
2019 Subaru Outback 2.5i Limited
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Repairing that awful fuel sender unit

Post by Petros »

The Professor wrote: Tue Jul 20, 2021 10:17 am ... If you have any valve lapping compound, apply some to the tip of the bit to help it bite into the bolt head .
that is an outstanding idea. never heard of anyone doing that, it really helps to have a new properly fitting philips tip too, there are several sizes. it seems heating the screws with a heat gun might help too, but I would not do that with a propane torch around a fuel tank.

last year I learned on my bicycle, when I installed some carbon graphite components to save weight, the bike shop does something similar. clamping the carbon seat post and handle bars without some kind of friction compound you risk crushing the carbon component in the traditional clamps when you get it tight enough so it will not slip. they just gave me some of their stuff in tub, felt like slightly gritty grease, but fine lapping compound would work even better.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
The Professor
Highest Ranking Member
Posts: 650
Joined: Wed May 12, 2010 6:38 pm
My tercel:: 1987 Tercel SR5 4WD wagon
Location: Western Washington
Contact:

Re: Repairing that awful fuel sender unit

Post by The Professor »

I spent the better part of 6 years on the aftersales side of a domestic OEM vehicle manufacturer, and was tasked with writing tech tips for our dealer mechanics. I've got loads of this sort of thing stored away, hahaha. WD-40 does wonders for removing butyl rubber, for example... :wink:
1975 Subaru SuperStar wagon
1984 Subaru Turbo-Traction wagon & hardtop
1987 Subaru RX 3-door
1987 Subaru RX Type-RA 3-door
1987 Toyota Tercel SR5 wagon
1999 Subaru Forester S
2002 Subaru WRX sedan
2019 Subaru Outback 2.5i Limited
User avatar
NWMO
Highest Ranking Member
Posts: 1615
Joined: Wed May 20, 2015 1:08 pm

Re: Repairing that awful fuel sender unit

Post by NWMO »

Hey Neu,

Have you made progress on this project? I am rehabbing my sending unit AND fuel pick up tube right now, I love the info on this site. In my case, the hex head screws for the pick up tube came out fine, but the phillips head screws for the sending unit were frozen. I ended up just drilling them out. Now, that was on a tank that is leaking and heading to scrap. On the parts car tank, I was a little more careful and only had to drill/tap about half of the holes. I'm hoping to test the sending unit tonight, I can see it needs to be cleaned and know it wasn't functioning well.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
Ala
Newbie
Posts: 1
Joined: Mon Sep 27, 2021 12:35 am
My tercel:: 1985 Toyota Tercel wagon

Re: Repairing that awful fuel sender unit

Post by Ala »

My fuel gauge was reading empty with a full tank. I pulled out the sending unit and gave it a good clean. It now only works for few minutes when I start the car in the morning when it is cold and then drops down to empty. Any suggestions out there? 1985 Tercel wagon fwd.
User avatar
NWMO
Highest Ranking Member
Posts: 1615
Joined: Wed May 20, 2015 1:08 pm

Re: Repairing that awful fuel sender unit

Post by NWMO »

Ala,

I cleaned mine AND removed the swing arm "stop" so I could clean the backside of the contacting arm and bend it slightly to improve connection. So far, so good, now if I could say the same for my parts car tank (leaks) and the rust filling my fuel filters :). My low level light still isn't working either.
You do not have the required permissions to view the files attached to this post.
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Repairing that awful fuel sender unit

Post by Petros »

Ala wrote: Tue Sep 28, 2021 11:56 am .., I pulled out the sending unit and gave it a good clean. It now only works for few minutes when I start the car in the morning when it is cold and then drops down to empty.
that can happen if the metal tab that holds the contact pad is barely touching the coil, when it changes temperature it moves it just enough to lose contact. I think if you can carefully bend the arm the contact is on to make better contact it should work. I did this on mine when I had it apart. you might also double check all the other contacts and wire connections for corrosion, and clean it if necessary.

BTW, supposedly you can make the low fuel sender work again my soaking it in solvent. I tried this with mine and it still did not work. so I never see the low fuel light on my fuel gauge, no matter, I just refill based on the level indication now that it works reliably.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
Post Reply