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Travis
Travis, Buick Technician
Category: Buick
Satisfied Customers: 980
Experience:  7+ years of GM dealership experience, GM ASEP trained, Assoc. Degree in Auto. Tech.
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My 2002 Buick Park Avenue fuel gauge seems to like the full

Customer Question

graphicMy 2002 Buick Park Avenue fuel gauge seems to like the full position although at times it does move to where I think the correct location may be.

I had the fuel sender/pump assembly in the gas tank replaced but the problem still exists.

Sometimes, when I start the car, the gauge appears to be accurate but then it creeps up to the full mark and stays there. Occasionally it will return to a reading that seems to be a little too high for the amount I think is left. I’m using the mileage since last fill up and the amount of gallons used since last fill up as an estimate of the gas left in the tank.

I suspect there may be an electrical ground problem between the sender unit and the fuel gauge but I have no clue where to begin. I'm open to bypassing the signal from the sender in the tank to the fuel gauge except I have no idea how to do that.

I have no wiring diagrams available.



Optional Information:
Year: 2002
Make: Buick
Model: Park Avenue

Already Tried:
Replaced the sender/fuel pump unit in the gas tank. Customer(Online) -- 3 Accepts / 4 Questions


Here is a photo of my sender/pump unit. The latest info on my problem: The Electronic trip odometer shows 177.2 miles. The Electronic fuel useage is 10.7 gallons used. The fuel gauge varies between 1/2 and 3/4 full right now.
graphic
View Full Image


Edited byCustomeron August 16 2009 at 4:54 PM Customer(Online) -- 3 Accepts / 4 Questions
Submitted: 5 years ago.
Category: Buick
Expert:  Travis replied 5 years ago.

Fuel Gauge Display

Resistance (?)

Fuel Remaining

E

90

12 %

1/4

128

30 %

1/2

170

53 %

3/4

205

72 %

F

235

92 %

Low Fuel Indicator On

101

16 %


Hello, and welcome back...

Here is chart you can use to help check the resistance coming from the fuel sender. Based on what you think the accurate fuel level is, the resistance reading of an ohm meter should agree if the reading is correct.

Now, if the resistance reading you get is correct with the amount of fuel in the tank, but the gauge is not reading correctly, then there could be an internal issue within the cluster. Testing the cluster is no so easy since it requires a special tool to do that.

You can use the purple and the black wires to measure the resistance of the fuel level sender. Also, check around the fuel pump area the make sure no wires are shorted or have been rubbed through by the metal lip around the pump.
Customer: replied 5 years ago.
Hi Travis,

Can you give me more exact instructions for using my VOM to check the resistance?

Rus
Expert:  Travis replied 5 years ago.
Sure, simply connect one lead of the VOM to the purple wire, and the other lead to the black wire. Set the VOM on ohm's and let me know what reading you get. You can insert the leads through the back of the connector where the wires enter at.
Customer: replied 5 years ago.
I had to unplug the four wire socket and I still could not touch the purple and black wires to get a reading. Do I need to skin the wires in order to get a reading?

Rus
Customer: replied 5 years ago.
Hi Travis,

While waiting for you I unplugged both terminals and then plugged in the pump terminal.

I checked the fuel gauge with the four wire sender terminal at the gas tank unplugged. It read FULL. When I plugged the terminal back in the fuel gauge shows just under 1/2 tank which should be correct.

Could the whole problem just be a bad connection? Let's hope so. :-)
Expert:  Travis replied 5 years ago.
Sorry for the delay Rus.
Yes, that is a good possibily, since then needle moved when you unplugged the pump, then we know there is a connection from the pump to the gauge. If the pump is a little loose, or not secured all the way, then that can change the resistance and cause a false reading.

Just to make sure, unplug the 4-pin connector at the pump and make sure the pins inside the connector are straight and clean.

Try it out for a day to 2 and see if it keeps working properly. If not, then some circuit check will need to be done.

Customer: replied 5 years ago.
Hi Travis,

I'll try it out for a few days to see if it is operating OK. I'll be back with you then to pay you or go for more help.

Thanks,

Rus
Expert:  Travis replied 5 years ago.
No problem Rus, let me know. If we need to do some wire checks, I can help you.

Thanks,
Travis
Customer: replied 5 years ago.
Hi Travis,

Here's an update on my fuel gauge problem:

This morning when I started the Buick the fuel gauge seemed to go to where it belonged; about 1/4 full since the electronic readout showed having used 15.2 gallons.

When I arrived at Costco to fill the tank the fuel gauge was reading close to 1/2 full.

After filling the tank the gauge went to past full and it took 15.6 gallons to fill up.

Should I continue to drive and monitor the gauge as the gas is used or do you have additional instructions?

Thanks for your patience.

Rus
Customer: replied 5 years ago.
Hi Travis,

Here is an update on my fuel gauge problem:

8/24: Fuel usage is at 4.5 gallons with 69.3 miles driven. The gauge is still past the "F" mark.

8/26: I started out driving with the fuel gauge on the "F" mark. I drove for 6 miles, the mileage is now 125 miles with 7.4 gallons used. On my return the fuel gauge is now on the 3/4 full mark.
Expert:  Travis replied 5 years ago.
Where did you have the new pump installed at?
Customer: replied 5 years ago.
I bought the fuel level from tanks-to-pans.com and had a auto repair shop install it on 7/27.
Expert:  Travis replied 5 years ago.
That may be the issue. The float sensor on the pump unit may not be set up for the ohm's that the gauge requires to operate correctly. If the resistance is off on the float, it will cause the exact issue.
Customer: replied 5 years ago.
I'm going to take the car back to the repair shop and have them ever so slightly bend the float arm up so the reading is more accurate.

Is that the way to go?

Brent
Expert:  Travis replied 5 years ago.
No, the fault may be in the resistance, not the actual position of the arm. Changing the arm position will simple move the resistance to another spot. You should have them check the ohms in comparison with the chart I sent earlier and see if they match.
Customer: replied 5 years ago.
What do I do if the ohms reading is wrong?

Does the female receptacle that is plugged in to the unit have to be connected or can the resistance be measured directly from the male prongs for the purple and black wires?

Do I need the ignition switch on or does the voltage come from the OEM meter?
Expert:  Travis replied 5 years ago.
Sorry, I had to run out and do an emergency brake job.

If the ohms are incorrect, then I suggest replacing the fuel level sending unit with a GM part. I shop should do this since the one they installed is not correct. That would be a starting point if the ohms are off.

If the ohms are ok, then the actually wiring will need to be test as well as the cluster gauge. The gauge will have to be done by a GM dealer since they must use a load tool that connects to the cluster in order to measure it.

The ohm's can be read from the male prongs after the connector is unplugged, but you will need to know how much fuel you have so you can compare the results to the chart. So start by measuring with a full tank and compare, then once the gauge seems off from what the tank level should be at, measure again to see if the ohms are out of spec.
Customer: replied 5 years ago.
My gas usage shows 8.9 gallons. That should leave just about 9 gallons in the 18 gallon tank.

Using two safety pins I penetrated the black and purple wires and then hooked up my VOM. I got a reading of 146.7 ohms.
Expert:  Travis replied 5 years ago.
Acoording to the chart, that should show between half and 1/4 on the gauge. Is that what you show?
Customer: replied 5 years ago.
My fuel gauge shows 3/4 full.
Expert:  Travis replied 5 years ago.
Based on the ohms reading and what your gauge says, it sounds to me like the level sensor is at fault. 3/4 tank should read closer to 200 ohms.
Customer: replied 5 years ago.
I bought the unit on line. I'm going to call them and arrange for a new unit exchange. I'll let you know. Sorry this is dragging out so long.

Expert:  Travis replied 5 years ago.
Thats ok Brent, keep me posted on what happens.
Customer: replied 5 years ago.
The company I bought the unit from is sending me a new unit today. When it arrives I'll check the ohms reading with the float at the top and again at the bottom. I should get accurate ohms readings of 235 ohms and 90 ohms, right?
Expert:  Travis replied 5 years ago.
Based on the specs for your car, that is correct. Those specs are straight from GM.
Customer: replied 5 years ago.
graphicPlease see the above photo for the wiring I'm talking about.

I received a new sender/pump unit and used my VOM on the purple and black wires and got no resistance readings.

I left the one clip on the purple wire tab and moved the alligator clip from the black wire tab to the two toned wire tab on the far left and got the following readings:

Float at lowest point=42 ohms
Float at highest point=244 ohms

Should I replace the unit currently in my tank with the new one or just take the car in to my local Buick dealer?

Travis, are you still with me?
Customer: replied 5 years ago.
I had the replacement unit installed and returned the first unit to the vendor. The fuel gauge is still erratic moving from full to half then later back to full.

Wednesday I'm going on a trip of 730 miles round trip so I'll see how the fuel gauge behaves during the trip.
Customer: replied 5 years ago.
The gauge seems to drop as gas is used but not as fast as the actual gas usage. With 10 gallons used the gauge just reached the 3/4 mark.
Customer: replied 5 years ago.
Is this problem a Buick issue that I will have to live with?

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Travis
Travis
93 Satisfied Customers
7+ years of GM dealership experience, GM ASEP trained, Assoc. Degree in Auto. Tech.