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Hi! I am encountering problem with fuel gauge:
When tank is 3/4-1/1 full, the fuel gauge is at E, becuase something "short to ground" code is current in self-diagnostics.
When tank is 1/2-3/4 full, the fuel gauge is at F mark.
After burning the half of the tank, fuel gauge begins to descent from F to E according to the fuel being burnt. So when I have last two gallons in the tank, it is already at E.

It just behaves like 2 and less gallons in the tank means E, 8 gallons in the tank means F, everything between 2-8 gallons is according position between E and F and everything above 8 gallons is "short to ground" and gauge at E. I am using FUEL USED trip computer information so I have no problems at all.
But it annoys me a little. Not so much to spent $200 for new fuel sender unit, but so much that I would like to look at fuel sender and clean/repair it at home if it is possible. I tried to search the forum, seems the fuel sender unit is defective quite often but I found no advices if it is possible to fix it at home. Thanks for tips.
 

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99 Seville STS, 08 STS4 N* 1SG F55
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3,516 Posts
There is an access panel in the trunk floor under the carpet to the front right. 3 bolts I think. After that you have to deal with the locking ring which is more challenging. I have the same problem with my 99 STS and have used the same solution with the trip computer. I have not read that you can R&R the sender - only replacement has been recommended in the posts I have read. Given that you're dealing with an electrical system suspended in a flammable liquid I would not recommend fooling with it as the potential risk vs. a $200 part are too high for me.
 

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1999 Black and Tan STS
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753 Posts
Ewill3rd had posted a factory repair kit for this problem, maybe search him or PM him... Seemed easy, I seem to remember about $120
 

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96' Eldorado, 00' Volvo 770 N14+ 525HP
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154 Posts
When I R&Red my fuel pump the carter fuel pump I got said it was recommended to replace the plug going into fuel pump plug, I bought the plug w/ my pump was like $17, but when I got the tank down and got a good look at the plug it was real clean...not sure if there was an issue at that plug at some point...Just a thought, maybe you got a bad connection at the plug. Evil 'green fuzzy sh*t'(GFS):nono: or the clean one 'green fuzzy stuff':lol:
 

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White Diamond '03 DHS (with DTS floor shift)
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'99+ has the access panel in the trunk. Not sure if the '98 did or not.
 

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1999 STS Z rated!
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44 Posts
Depending on your ability, you can likely do this. Just bought a 1999 STS WOW what a car!! It does have a few issues, one of them being the erratic fuel gauge.

If you have concerns about staring into 10 gallons of fuel through an open hole in the trunk, then DON'T DO IT!! I've replaced fuel tanks before - it's not my favorite thing to do but with some precautions, it can be made relatively safe. Open all the doors so that any fuel vapors will be blown away. Always touch metal in the trunk so you don't create a static spark.

I found this link for the replacement of the sensor in a Bonneville, it's essentially the same for the Seville: http://www.bonnevilleclub.com/forum/viewtopic.php?=&p=819381

Additional tips from my experience:

- You CAN pound the lock ring off with a hammer and brass punch but the whole job will be a lot easier if you can borrow or purchase the correct lock ring wrench. I have seen them on eBay. I pounded mine off but it took several hours because there was quite a bit of rust holding things together.

- I bought just the sender on eBay - it was less than $30. Once you get the whole pump/sender unit out, you can replace just the sender. One plug was wrong so I had to splice the old plug onto the new sender wires. Solder the wires and remember that the wires are in gasoline so don't use electrical tape if you have do this, use shrink sleeves.

- Now this one is important but not mentioned in the Bonneville instructions: BUY A TANK SEAL (AC Delco G27)!! Otherwise, you will be removing the pump/sender assembly all over again to replace the seal. Don't ask me how I know. Well, ok, the original seal was an o-ring on my tank. Evidently, after years of exposure to gasoline vapors, the seal swelled a little bit and just wouldn't fit back into the groove. As a result, once I filled the tank, as the gas sloshed around, I had a leak at the old seal. This problem also set a code for an EVAP problem. The new seal is flat with raised portions, a much better seal. So, save yourself some aggravtion and just replace the seal - about $20.

So, you can do this whole job for less than $100 if you buy the special wrench and less than $50 if you don't. Just be extra careful working around all that fuel. And by the way, thanks to everyone for the posts on this forum, I've already used some of the info for working on the new (to me) Caddy.
 

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96' Eldorado, 00' Volvo 770 N14+ 525HP
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154 Posts
Wow, you STS guys have a steel fuel tank? Mine was plastic, I just used a screwdriver and hammer to get my lockring loose, didnt have to worry about sparks was all plastic.
 

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1999 STS Z rated!
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44 Posts
You are correct, sort of - the tank is plastic. However, the lock ring and the lugs that grab the lock ring at the tank opening are steel.
 

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98 Concours, 2004 Deville DTS
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188 Posts
I just thought I would mention that I bought the exact tool for the lock ring and ended up using a hammer and brass punch :) . The tool was hard to use with just one person as you really need someone to hold the tank while the other person takes the lock ring off with the tool. I found the punch and hammer worked great.
 

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Cadillac 200 STS
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2000 STS : same problem. Fuel gage works OKdown to 1/2 tank then goes back to full. Reset tripometer at each fill up. My dealer says it will cost $400.00 plus to install new. I'm ordering the $25.00 part from E-Bay.
 

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I have the same problem. Has anyone else encountered a "stuck" lock ring? I have tried so many different things including the hammer/punch, impact wrench, a tool made that applies pressure to each point. Nothing worked. It wouldn't even budge.

Does anyone have a picture of the specific tool?

I'm thinking of possibly cutting out the lock ring and just replacing it with a new one found on rockauto.com (ACDELCO Part # TR7 More Info {Ring replaces 21010287 #25691383}
CAM,FUEL SDR)

I've really tried an insane amount of force and the damn thing seems like its rusted on and stuck.


Any help would be appreciated.
 

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1997 ETC (GAVE TO STEPSON 2011), 2000 DTS (RIP)
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1,702 Posts
Are you turning it the right way? Are you trying to turn the right thing? No offense - just asking
 

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1997 ETC (GAVE TO STEPSON 2011), 2000 DTS (RIP)
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Wow, you STS guys have a steel fuel tank? Mine was plastic, I just used a screwdriver and hammer to get my lockring loose, didnt have to worry about sparks was all plastic.
Does the '96 Eldo have an access panel, or did you have to drop the tank?
 

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1999 STS Z rated!
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44 Posts
I have the same problem. Has anyone else encountered a "stuck" lock ring? I have tried so many different things including the hammer/punch, impact wrench, a tool made that applies pressure to each point. Nothing worked. It wouldn't even budge.
All I can tell you is to keep trying. Soak the whole area with penetrating oil, let it sit overnight, try to pound it off then repeat until it goes. Thanks to the salt used here in New England in the winter, mine was rusted on pretty good. As I said in an earlier post, I spent a couple of hours trying to get that ring off. Finally, it let go. If you can manage to cut it off, that should work, finding a new lock ring isn't a problem. Just be careful cutting it off - no sparks!!!

Good luck.
 

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White Diamond '03 DHS (with DTS floor shift)
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Tateos, I do not think the '96 has an access panel. I believe that came about in '99 (maybe '98).
 

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2004 Seville STS
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271 Posts
I had the jumping fuel gage problem (from fuul to empty then back to full) in my 03 Seville STS. I did not know about the sender on ebay, just the expensive ones from GM. (Sender only or complete pump and sender.)

With 96K miles on the car, I opted for an aftermarket sender/pump made by Airtex, complete with wiring pigtail, I just installed it yesterday.

It did fix the problem, but the fuel gage fluctuates quite a bit when going up and down hills. Is this normal in these Sevilles?
 

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'12 Regal GS, '01 Trans Am
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248 Posts
I have the same problem. Has anyone else encountered a "stuck" lock ring? I have tried so many different things including the hammer/punch, impact wrench, a tool made that applies pressure to each point. Nothing worked. It wouldn't even budge.

Does anyone have a picture of the specific tool?

I'm thinking of possibly cutting out the lock ring and just replacing it with a new one found on rockauto.com (ACDELCO Part # TR7 More Info {Ring replaces 21010287 #25691383}
CAM,FUEL SDR)

I've really tried an insane amount of force and the damn thing seems like its rusted on and stuck.


Any help would be appreciated.
I had this problem doing the fuel pump on my Trans Am. I could get it to move just a hair with a hammer/punch (PS - MAKE SURE YOU USE A BRASS PUNCH AS IT WILL NOT SPARK! A STEEL ONE WILL!) before no amount of force would budge it. I soaked it in PB Blaster - works way better than WD40 - and what I did is use a flathead to pry on the area between the tab and notch for each of the points on the retainer ring that had opened up ever so slightly with the minimal rotation of the ring. A couple hours of prying and banging with the punch, and it finally came loose.

Unfortunately it can be a real pain in the rear to loosen those retaining rings.
 

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Cadillac
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thank you. i hope i luck out with that lock ring. i will offer someone money to heat it up with a tourch for me lol j/k. after working on forklifts all week now i got to work on my car for the weekend. sucks
 
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