QuestionQUESTION: The fuel gauge shows full all the time on a 87 lebaron convertible. The low gas warning symbol works. I can see an electrical connector into the rear side of the tank. I cleaned these just to make sure. Any ideas as to what the problem might be?
ANSWER: Hi Herman,
The three wire connector for the fuel sender has two wires that are a variable resistance depending upon the level of fuel in the tank. So if you read the resistance between the two outside pins of the sender itself (the ones to which the dark blue and the gray trace wires are attached) you should find that the resistance reading will decrease as the tank empties out. So my suggestion would be to read the resistance when the tank is full or near empty and then read it in the opposite condition and see if the resistance has changed significantly or not. If not, then the float is hung up on the sender so you could remove it and see if you can free it up. If it seems to be responding, then I would suspect that there is a disconnect in the dark blue wire between it and gauge, or the gray trace wire which is a ground tie to the left rear quarter panel has come loose or is corroded. You might try checking that ground point first. That the low gas warning "works" suggests though that it is not the ground problem but rather the float inside the tank, or the dark blue wire is "open" somehow between the gauge and the sender. The warning light is the third pin (light blue trace) and when the tank hits the low point, it becomes connected to the gray trace pin (ground).
Roland
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QUESTION: I had not driven the car since i cleaned the wires. I drove it last night and the fuel gauge worked intermittently. So I think maybe the dark blue wire has a bad connection somewhere. I also asked you a question on a different submission about an O2 sensor because you were not available from this one at the time. I will disconnect the battery to reset the codes and then drive it and try again before i CHANGE THE SENSOR. iS THIS WHAT YOU ARE SAYING?
ANSWER: Correct, Herman, if the code 51 doesn't reappear then I would not change the sensor.
On the fuel gauge, it could be that the intermittency is in the fuel level float wiper of the variable resistor in the sender unit rather than the wire. You could test for that if you can get it to sit still either in the 'true' position or the false full-scale position and get a reading of the resistance and of the dark blue wire's continuity from the plug back to the gauge.
Roland
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QUESTION: Code 51 reappeared. gas milage 17 mpg. Ran smooth.
On the Fuel gauge. The connector to the tank has thre wires. Black and red/blue strip opposite each othe and white as third. From white to black .8 reading with ohm meter set to -200 and nothing on the others. The connector to the body has two blacks toghether and two reds together opposite each other and the white to the third. Here the white and the two reds have a 4.0 reading with ohmeter set to -200. Can I send you pictures of this plug or don't you need them?
AnswerHi Herman,
Those wire color assignments (as shown in the manual) don't agree with the '87 fuel sending units for any of the LeBarons (there are actually three different body styles: the J-body convert/coupe, the H-body GTS, and the K-body). But only the H and J have a low fuel warning so you must have one or the other.
I would recheck the resistance between the black and the red/blue strip assuming those are the ones at the "base" of the triangular connector after you have either emptied or filled the tank. If the resistance is unchanged then I would remove the sender and see if the float is stuck.
On the 51 code, if that 17 mpg mileage seems low, then I would recommend changing the heated oxygen sensor.
Roland
