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I have a 2000 Deville Base Sedan and have recently experienced faulty readings from the fuel gage. When the tank gets below half full the gage goes up and down from a reading of full to almost empty. It continues to do this until I refill the tank. I get normal readings if the tank is over half full. Has anyone had this problem and if so what was the fix? Thanks
 

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Welcome aboard,
The only issue I've seen with these is the tank unit (fuel gauge sender). Cadillac has had problems with these little beauties for years. You'd think they could fix something so simple wouldn't you. :rolleyes:
 

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Katshot said:
Welcome aboard,
The only issue I've seen with these is the tank unit (fuel gauge sender). Cadillac has had problems with these little beauties for years. You'd think they could fix something so simple wouldn't you. :rolleyes:
Yes it can be fixed its most likley a sensor inside the fuel tank. I had the same problem with previous cars. Its not worth it in my mind to even bother b/c i hate doing it. It is also expesnive to have someone else to do it. That is why I NEVER go by what the gas gauge says i go by mileage.
 

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Mitchs said:
I have a 2000 Deville Base Sedan and have recently experienced faulty readings from the fuel gage. When the tank gets below half full the gage goes up and down from a reading of full to almost empty. It continues to do this until I refill the tank. I get normal readings if the tank is over half full. Has anyone had this problem and if so what was the fix? Thanks
i have a problem like that but mine shuts down sometimes when fuel changes does yours?
 

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both my chevy pickups had furl gage problem, 1987 and 2000
There was recall in Canada about the gages but they would only look at if it still unwarrenty
When I fill the 2000 the gage goes from full to empty to full to empty and so on until the tank is 3/4 full than it works OK
 

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I agree, faulty fuel level sending unit.
My short story, 2 weeks after taking delivery of the car I noticed the fuel gauge was all over the place 1/2,3/4,1/4, never sure how much I had, well the one time it read "E" it really was!

Walking to the gas station stinks!

Mine is Certified so I didn't have to do the dollar dance.

Paul P.
New England
 

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I had nearly the exact same problem on my 97 Deville. The gage worked fine till 7 gallons. Then the gage would slowly climb back to about 13. No matter how low the actual fuel amount was. The dealership replaced the tank sending unit. I can't remember what the charges were. Not cheap though.
 

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Hi! Yes, I have exactly the same problem on my '97 DeVille! It all started when I did this very steep downhill turn where the car was very much "nose down" -- it was at the parking garage at National Airport (DCA). The gauge worked fine until then and something went nuts. Now it works fine until about 9 gallons and then it starts counting UPWARDS! Beyond strange.

You mentioned the fuel sensor in the tank needed to be replaced. I checked the books and this is part of a big pump assembly, as well. Did you have just the sensor replaced or the entire pump/sensor assembly changed? That's like $600.00 without the labor, as I recall.

Did it resolve the problem, or has it come back?

Thanks for the help!

Chuck
 

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Did anyone have the price for this repair and is it something you can do yourself? Mine is doing exactly the same thing (97 Deville). Thanks
 

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Well, I still have not had mine fixed. I'm trying to get my mechanic to do it but since it is not a particularly critical problem, we have both put it off.

From the posts I have seen, the solution is to replace the sending unit. Can you do the work? It's too much for me, but if you have a garage, fuel drainer, some lifts, the tools, and the expertise, and know all the safety issues, I guess you could! Not me though!

I have the two large maintenance manuals directly from GM. The good news, if any, is that according to the manual, "...The serviceable components on the Modular fuel sender are the fuel sender strainer, and the fuel level sensor assembly...". So, I take it that this means one need only replace the "fuel level sensor" component rather than this huge contraption with a reservoir, a pump, vents, valves, and so on. Still, I have heard this is a $600.00 part.

Now the strange piece of this puzzle to me is where the tank is accessed. I cannot determine, from the manual, if the tank must be "dropped", or one can access it from under the back seat. The manual reads, "...[the tank] is located in front of the rear wheels. It is held in place by two metal straps attached to the underside of the vehicle.". It appears in the diagram that if access is available to the top of the tank, it would be under the right-side (passenger, opposite driver side) REAR seat. It appears that one would have to extract the entire "Modular Fuel Sender" unit from the tank -- think James Bond pulling the detonator out of the nuclear bomb (and with all that gas, I'm probably not far off with my analogy!). Once that is out, the "Fuel Level Sender Assembly" could be replaced. That looks like the easy part(!).

The manual reads, "The fuel level sender attaches to the outside of the reservoir and measures the amount of fuel in the tank. [No shit, Sherlock!] The fuel level sender consists of the following components: the rheostat, the float, and the float arm. The assembly converts changes in the fuel level to a variable electrical signal used to drive a guage (sic) in the instrument cluster. An electrical harness attached to the fuel sender cover connects the rheostat to the vehicle's wiring harness." My bet is the rheostat is toast.

Well, I hope that is enough to get you started. I'll make a disclaimer here -- personally, I would not attempt this at gunpoint, but I'll leave that up to you. Please let us all know how it works out. Oh, yes, I hope you don't smoke! Make sure those seals are good and secure, and the wires are insulated!

Good luck!

Chuck Gage
 

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Got a 97 sts with the same problem it works ok up to about half a tank then starts going nuts. Has anyone pulled any codes for this? I get a code that says that the wire is open or shorted to B+ anyone else get this?
 

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SonicSTS said:
Got a 97 sts with the same problem it works ok up to about half a tank then starts going nuts. Has anyone pulled any codes for this? I get a code that says that the wire is open or shorted to B+ anyone else get this?
Very interesting!

I have not run any codes on this. Very good idea, though. What do feel the code means? Could this be a wiring problem that is fixed outside of the "fuel level sensor"? Obviously, if there's anyway to fix this without having the mess around with the fuel-tank and fuel level sensor, all the better.

Appreciate any input. I still haven't done anything with mine, yet.

Chuck
 

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I suppose most of my questions are answered.

If its the same, Ive taken down the fuel tank and changed the pump in a Chevy Cavalier.

I lifted the rear and put it on jack stands.

tried to syphen the gas out of the tank.

placed a jack with a flat piece of wood under the tank to support it.

removed the two straps holding up the tank.

lowered the jack alittle bringing down the tank just a bit to remove the {5 I think hoses and tubes} and disconnected them.

brought the tank all the way down and unscrewed the fuel pump. {removed it}

replaced it the opposite.

I purchased the used fuel pump from the junk yard for about $20.00 and didnt charge myself anything. It took about 4 hrs and learned at the same time alone. If I would have known how to do it. It probably wouldnt have taken as much time.

Now my problem:rolleyes: does anyone know if its he same set up
 

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The good news IS....

You dont have to drop the tank. Earlier Devilles you must drop the tank. The 2000 and newer have a access panel in the trunk. I was going to post a picture, but the server is down.....arrrgggghh.

Anyways, pull the carpet out....you will see the hatch plate.

Logan
www.airbagcrash.com
www.logandiagnostic.com
 

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Thats wonderful:annoyed:

I have a 91' and my mother inlaw has an 88'.

I suppose I need to drop the tank huh?:confused:

O well. gotta due what I gotta due.:helpless:
 
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