# How to pull and clean the sending units on your Mk1 TT - lots of photos



## lite1979 (Sep 9, 2005)

Does your gas gauge read full all the time? You might have junk on your sending units that's messing up the reading on your gauge. It's pretty common in places where ethanol is added to the gasoline supply (like here in upstate New York - this started happening to me in Utica, but continued to happen to me after I moved to Buffalo). Some people can run Chevron Techron or a similar fuel additive to a full tank every oil change and never have the problem, but after doing that a few times, mine started giving me problems again.

Note: This is a USDM car, so driver's side is the left facing forward; passenger's side is the right. Our UK, Aussi, and Japanese brethren will have to swap those terms, obviously.

Things you will need:

Phillips screwdriver
Flathead screwdriver
Hammer
5 gallon bucket that holds fluid (or another container big enough to hold your fuel pump/sending units - you don't want to get gasoline all over the place)

It always helps to have a Bentley repair manual on hand, too!


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First, remove your rear seat (coupe) or rear plastic trim (roadster). You'll see one cover with three phillips head screws in FWD models, two (like pictured) in quattro models. The quattro models have a gas tank that's "butterfly" shaped to allow room for the propeller shaft.


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Once you remove these covers, you'll see the feed (black) and return (blue) fuel lines, the electrical harness, and a ring securing the pump/sending unit into the tank.

Driver's side - there is no actual pump on this side; just a fuel line loop that siphons fuel from that side and dumps it near the bottom of the pump/sending unit on the passenger's side, but there is a sending unit. Be sure to remember the position of the arrows before you pull them out.


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Passenger's side - note the big arrow for the positioning of the unit, and smaller arrows for the feed/return lines:


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You have to press in the side here to get the fuel lines off of the unit. This can be done by hand, but I used a screwdriver for ease of viewing:


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Here you can clearly see the feed and return arrows. The plastic fuel lines have plenty of wiggle room, but you should still exercise caution when moving them and working around them.


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Maybe ask your pets to help! (they won't)


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I didn't take a picture of it, since it took two hands, but I removed the retaining ring using a hammer and a flathead screwdriver. Don't use too small a screwdriver, as it's more likely to cut into the plastic; there's a special tool you can obtain for this as well. Home Depot sells one here. I'm not sure if they stock it in stores, though.

Once the retaining ring is off, you'll probably have to use a little muscle to get the unit out, but don't force it. There is a spring between the pump and the top of the unit, and once you get it moving, it should pop right up:


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Separating this connection was the hardest part of the job, and it still wasn't that bad. The small part that goes to the fuel pump assembly is the male - the connector and the tubing that leads to the other half of the tank is the female. You'll have to squeeze the retaining ring like the feed and return lines to separate them.


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That black thing in the middle of the photograph below is the electrical connector for the driver's side sending unit. You have to squeeze one side (the male) to remove it from the female side:


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The small white plastic thing here just holds the returning hose from the other side of the tank and directs the fuel downward. You can just pull up on it and it should come off. When you put it back on, it'll click into place.


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I didn't know how much slack I had (turns out there's plenty), so I waited to disconnect the hose from the pump to the other side until last: Here it is, disconnected:


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I had to use two hands to get the pump out once everything was disconnected. It didn't give me a hard time, but you'll want to pull up as much of that hose as possible, and also lift the seal (gray rubber ring in the pics) out of the hole to remove it. Have your bucket handy.

I had my rear hatch open the whole time I was doing this because huffing gas is not only bad for you, I also hate the smell of gasoline. Try to get the bucket under the unit while it's dripping directly into the gas tank to minimize spillage.

Now, with the fuel pump and sending unit out of the car, you can clean the contacts for the sending unit!

I originally bought some 80-grit sandpaper to do this, but it turned out to be way too coarse, so I used a pencil eraser instead, and it did a great job!


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Before:


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After:


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You can see a few scratch marks from trying the sandpaper first, but the eraser worked great.

I left the main pump/sending unit out of the car while I pulled the other one. It didn't want to just slide out, though.


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I lifted it part of the way out, then disconnected the two parts, which are attached like a hinge.


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Now I could pull the tubes and wires through from the other side and remove it from the tank.

Before:


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After:


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I don't think the pictures do justice to how well the eraser worked, but if anyone has a better idea, feel free to chime in. Erasers are made for removing carbon (albeit graphite), so I was glad to see that's what other people have used in similar situations:

http://www.infinitiscene.com/forum/threads/13056-Gas-Gauge-Level-Fix

http://www.pelicanparts.com/techart...ent/15-FUEL-Fuel_Level_Sender_Replacement.htm

http://www.alfabb.com/bb/forums/ele...-fuel-tank-sending-unit-repair-procedure.html

Reinstalling the sending units wasn't that hard. Just make sure you put the driver's side one in first so you can fish the tubes and wires through to the pump side, and make sure that stuff is out of the way when you put the pump back in. Re-connect everything, make sure your arrows are where they were when you started, and put some gas in the tank. It probably won't start the first try because you'll have introduced air into the system, but by the second or third try you should be running again.

Note: The Bentley says to replace the seals. I didn't. If I have any EVAP problems or wonky fuel levels, I'll update this post. As of right now, I have a full tank, and I'm going to Syracuse to see my Mom sometime next week, so that'll be a good test of this maintenance procedure.


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## Alec's TT (Jan 28, 2013)

lots of broken pictures :/


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## Sniper911 (May 30, 2015)

what he said - I can't see a single pic 


Sent from my iPhone using Tapatalk


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## MÄDDNESSS (Oct 18, 2010)

Pics dont work.


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## lite1979 (Sep 9, 2005)

%&+! Google! I'll host them somewhere else later tonight. Thanks for letting me know.

Sent from my XT1254 using Tapatalk


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## mister-j (Apr 20, 2016)

This is great but none of the photos display. Can you fix that please. Thanks


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## lite1979 (Sep 9, 2005)

Fixed! I had to make an album and share it publicly on Google+, then right click each one and copy the URL. Verified with an incognito window; all pictures should be visible to everyone now.


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## MCPaudiTT (Nov 26, 2006)

lite1979 said:


> Verified with an incognito window; all pictures should be visible to everyone now.


Confirmed. Nice job, and thanks for your service to the TT community!


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## 20v master (May 7, 2009)

So is your gauge accurate now?


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## lite1979 (Sep 9, 2005)

Yes! Near full is where it used to give me the most problems, and I would also see it drop down and jump back up from time to time; none of that so far. I've only put about 40 miles on it since I did this, but I have a road trip coming up today or tomorrow that will let me drive it right down the rest of the gauge. No EVAP problems to speak of, either (I re-used the seals).


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## lite1979 (Sep 9, 2005)

End-of-tank report:

Everything went well on the way to Syracuse from Buffalo. No surprise gauge readings, no unexpectedly high miles-to-empty. After stopping in Syracuse, I took Route 5 to my home town of Canastota to see my brother and sister-in-law, and everything acted normal.

Went back to Syracuse this afternoon from Canastota, and saw my Mom again. When I left, the fuel gauge read just a tad higher than when I arrived, but I was on some hills, and I was parked on a bumpy gravel lot. Gauge went slowly back down to where it was in a matter of minutes, then read accurately for the rest of the trip back to Buffalo.

I didn't fill up at all during the trip, and when I parked in my driveway a little while ago, the gauge read almost empty, and the MFD says I have 20 miles to empty. 

P.S. I got excellent gas mileage the whole way there and back!


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## marcTT (May 25, 2021)

Might be a little late to the party but I'm planning on working on my TT but I can't see the pics at all now. HELP!


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## lite1979 (Sep 9, 2005)

Google keeps changing permissions on their photos in Google Drive. Once I get back from my honeymoon I will try to change permissions or re-host.

Sent from my motorola edge plus using Tapatalk


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