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Fuel Gauge is erratic and not accurate on wife's 2000 DeVille; 185K on the vehicle, 20K on a new engine installed to resolve oil leak.

This is the third time I've experienced this problem in the past 2 - 3 years on this vehicle.  I'm no longer physically able to do the R & R on this part, located under the spare tire, and it's getting expensive when performed by my local Indy or the dealer at $350-$425.00 a pop.  I've tried the Techron Concentrate in the past with no success.

Inconvenient, but  I'm now recording the 'Trip Mileage' and filling the tank at 250 mile intervals.   Any suggestions would be appreciated.

Thanks much,

Pgh. Steve 

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Interesting.  I assume you are changing the fuel sender unit each time.  How many miles are you getting from each sender?

Are you also changing the fuel filter?  

Are you using major name brand gas?

I would suspect there is some sediment, rust, dirt, or debris killing the senders.


Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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Bruce,

Installed a new OEM fuel pump and car running fine, but fuel gauge still not working accurately.  ImyIndy suggest the 2000 Deville may not have a fuel filter!!

Can you tell me where the fuel sende runits are on wife's 2000 Deville?

Thanks much,

Steve

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I believe the fuel level sending unit is part of the fuel pump which means it was replaced with the pump. 

Does the fuel guage work at all?

Have you checked for codes?  The fuel level system will set codes.  

Do you know how to check codes through your dash?


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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You mentioned the fuel filter.  Your mechanic told you the 2000 doesn't have one?


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Ok, I checked your owners manual, you DO have a fuel filter, see page 6-71 of your owners manual for the part number.  It is typically under the car in the area in front of the right rear wheel

Screenshot_2017-05-06-09-14-24_zps69vlf7

 


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The fuel filter is the sock on the pickup tube.

Not sure what happened exactly but the fuel pump can be replaced without replacing the entire unit. The wiring to the sender should be checked especially at the sender itself.


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Yes, there is a sock on the fuel pump, but there is a secondary in line filter under the car in front of the RR tire.  Its the AC Delco GF-627 here is a photo of it

https://www.knfilters.com/mobile/cross_reference/ac_delco/gf627_fuel_filter.aspx

 


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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@OldCadTech is correct, they MIGHT have replaced the pump and used the old level sensor but most of the time the level sensor is included.  

Please check codes, it may direct us to a problem


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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@BodybyFisher You're right, I didn't type the response correctly. I should have said there is a another filter on the sender. Sometimes what I'm thinking and what I type are not the same :wacko:

Another thing that causes an inaccurate sender reading is the baffle in the tank breaks loose and interferes with the float causing all kinds of weird fuel level readings.

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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4 minutes ago, OldCadTech said:

@BodybyFisher You're right, I didn't type the response correctly. I should have said there is a another filter on the sender. Sometimes what I'm thinking and what I type are not the same :wacko:

Another thing that causes an inaccurate sender reading is the baffle in the tank breaks loose and interferes with the float causing all kind of weird fuel level readings.

:hatsoff:


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Son installed complete OEM pump out of the box.  No codes showing after the R & R of the fuel pump, and car is running fine.  BUT . . . last night the message "Theft Protection" popped up again.  Shut down engine for a few minutes and message has not reappeared:-[????

I filled the tank and will check to see if R & R did anything at all to resolve problem with inaccurate fuel reading.  Next job will be to replace fuel filter ASAP.

 

Pgh Steve

 

 

 

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The fuel filter should have no bearing on the accuracy of the fuel guage.

OldCadTech mentioned a baffle in the tank.

It is possible that the guage itself is bad. 

We need a wiring diagram and diagnostic tree for this.  


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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