Post by 99rorabahn on Feb 18, 2012 11:04:54 GMT -6
This thread is focused around fixing the problems that cause faulty gas gauges. Whether your gauge is inaccurate, fluctuates, is stuck at the full position, or stuck at the empty position. I am not responsible for any parts that may be damaged during these procedures, there is always a possibility for parts to break after they have been resting in their original place for over 15 years. Just be careful and take your time and you should be as good as gold.
Below i will explain step by step how to resolve an inaccurate or fluctuating Gauge. The main reason that fuel gauges are inaccurate or fluctuate is due to the level arm in the tank that is connected to the float. this arm has two contacts on it that allow current to flow through resistors which then go to the instrument cluster to control the gauge. In most cases these contacts will wear over the life of the car and no longer generate a good connection. In this circuit a full tank of gas causes the resistance value to be high. and a empty tank of gas causes a low resistance.
The solution to this fix is to replace the little arm that has the two contacts on them. If you open up your fuel tank and notice these contacts are worn i would suggest replacing them even if it doesn't solve your original problem.
Materials:
New fuel level arm * Look at picture below for Part #*
Hammer
Screw driver or equivalent
Pliers * needle nose preferred*
Two sockets of equal size
First step is to verify the complaint...
Although this gas gauge is not fluctuating it is however stuck in the full position. As you can see that the car was driven 103 miles and the gauge did not budge the full position.
The next step is to relieve the fuel pressure by letting the car sit for a little bit to let the pressure go down on its own. You can also try to run the car with the fuel pump relay removed.
Once the pressure is relieved then you need to remove the carpet from the trunk to gain access to the fuel pump/ sender access plate
Now you need to remove the cover bolts that hold it down. When you are prying on the cover it is key to be careful not to ruin the seal around cover. This seal keeps water from entering the trunk and getting soaked up by the thick insulation attached to the carpet which could cause mold/ mildew.
After this cover is carefully removed it will look like the picture below.
The next step is to remove the fuel lines from the sender assembly. To do this you need to use the pliers to depress the plastic tangs at the end of the line and pull the lines from the assembly. Keep some shop towels around to soak up the fuel that will leak from the lines. After the lines are taken care of then you need to remove the Two electrical connectors. One is for the Fuel tank pressure sensor and the other is for the fuel pump and level sender.
After everything is removed from the top of the sender then comes the fun part. The lock plate will most likely be rusted to the tabs on the tank and it will need to be hit a lot to get the plate off.
After you remove the lock plate from the fuel tank the Fuel sender assembly can now be pulled out of the tank. Keep in mind that the assembly is filled with gas and should be tilted on its side over the tank to let the gas drain back. otherwise it will spill all over the place when you start to work on it.
This is a picture of the assembly once it is pulled from the tank and drained of fuel.
The next step is to un-clip the electrical harness that has the wires for the sender and fuel pump from the whole assembly. Then it is time to un-clip the sender from the assembly by depressing the two tabs that hold it in place and sliding it off grooves that it sits on.
Once you have the sender off the assembly then it is time to remove the float from the sender. It is held into place by tabs on the little arm that is going to be replaced. Just pry it off with a small screw driver being extra careful not to bend the float. if this gets bent than it could potentially cause an inaccurate gauge. Once it is removed it will look like the picture below.
Now it is time to remove the arm from the sender. Balance the front of the sender on the two sockets and use a screwdriver and the hammer to tap the pressed in brass retainer. Be careful and take your time since you are just replacing the arm you don't want to damage the scale that the resistors are on or else you might have to get a whole new sender.
After you remove the old arm now it is time to do the same thing with the new sender. Be extra careful with the new part because you don't want to disrupt the new contact points. After you have both parts removed compare them side by side to verify that they are the same part. You will also notice the extreme difference in the contacts.
After you verify they are the same part now you need to install the new arm on the sender. To do this just balance the back of the sender on one socket under the brass retainer and use the screwdriver and hammer to tap it in place. Tap it enough so the arm can move freely while also making sure the contacts are touching the resistor scale at all times. After the new arm is installed it will look like this.
Now all you have to do is put the sender back on the assembly and connect the harness and put the assembly back into the tank. After you have completed the repair verify that the new part fixed the inaccurate or fluctuating gas gauge.
Although this fix will work on fluctuating gauges it may or may not work on a gauge that is stuck at full or empty. In my case after i had performed this service my gauge still was at the full position.
If this repair does not work then it is time to get into the electrical diagnosis of the whole fuel sender circuit. Below is the diagram of the circuit
In this circuit There are two basic wires going to the fuel sender. There is the Purple wire ( PPL) and there is the Black and white wire ( BLK/WHT). To test these wire to make sure they are in good condition you should test the resistance of them to ensure they will carry the current that the computer sends it. To do this effectively you should remove the cowl above the Instrument cluster to gain access to the Cluster harness/ connector. Disconnect the connector on the right. it should look like the diagram below
** DISCONNECT BATTERY BEFORE USING OHM METER**
Now use a pin to back probe terminal C2 which you will notice is the purple wire that is coming from the sender. After this terminal is back probed now you need to back probe the connector in the trunk. And using an Digital Multimeter on the OHM function measure the resistance of this wire.
The resistance of this wire should read 0000 OHMS if it is in good shape. next do the same with the BLK/WHT wire that goes from the sender to the cluster. The wire on the connector to the cluster is terminal C13. This wire should also read close to 0000. If these wire do not read 000 then that means that there is a restriction in the wire that is causing it not to allow current to flow. The solution is to follow the wire from the sender in the trunk back to the instrument cluster and observe if there is any obvious problems that stick out. such as corrosion or a broken wire. But if these wires prove to be good and the sender in the tank is good than the problem is probably in the instrument cluster and can only be solved by replacing the cluster.
My Findings:
After i replaced the sender arm in the tank my gas gauge was still stuck in the full position. And by looking in the tank with the sender assembly out i knew there was not much gas left in the tank. So i tested the resistance of the PPL wire and the BLK/WHT wire
These were my results:
PPL = 1.994 Million Ohms of resistance
BLK = 3.00 Ohms of resistance.
So obviously there was something wrong with the purple wire. The black wire i figured 3 ohms wouldn't make the big of a difference so i didn't even bother looking for the cause of that resistance. So the next step i took was to follow the PPL wire from the fuel sender, and right away i discovered the problem that was causing the high resistance. The wire had rubbed against the under body of the vehicle for so long that it actually caused the insulation of the wire to wear at that spot. and as water found its way on the copper it corroded the wire so badly that the wire was only held together with green dust. After cleaning up the wire and crimping the two ends together i then tested the resistance of the PPL wire again, Except this time the resistance was a perfect 0000. So after i put everything back together my gas gauge was working again. Although it said i only had 2 gallons left i then went to the gas station to top it off and it took exactly 16 gallons to make a complete 18 gallons which is the specified FULL amount.
I hope this write up can be helpful for those of you that have lived with the faulty gauge and have found no solution to the problem.
EDIT; pic resized
Below i will explain step by step how to resolve an inaccurate or fluctuating Gauge. The main reason that fuel gauges are inaccurate or fluctuate is due to the level arm in the tank that is connected to the float. this arm has two contacts on it that allow current to flow through resistors which then go to the instrument cluster to control the gauge. In most cases these contacts will wear over the life of the car and no longer generate a good connection. In this circuit a full tank of gas causes the resistance value to be high. and a empty tank of gas causes a low resistance.
The solution to this fix is to replace the little arm that has the two contacts on them. If you open up your fuel tank and notice these contacts are worn i would suggest replacing them even if it doesn't solve your original problem.
Materials:
New fuel level arm * Look at picture below for Part #*
Hammer
Screw driver or equivalent
Pliers * needle nose preferred*
Two sockets of equal size
First step is to verify the complaint...
Although this gas gauge is not fluctuating it is however stuck in the full position. As you can see that the car was driven 103 miles and the gauge did not budge the full position.
The next step is to relieve the fuel pressure by letting the car sit for a little bit to let the pressure go down on its own. You can also try to run the car with the fuel pump relay removed.
Once the pressure is relieved then you need to remove the carpet from the trunk to gain access to the fuel pump/ sender access plate
Now you need to remove the cover bolts that hold it down. When you are prying on the cover it is key to be careful not to ruin the seal around cover. This seal keeps water from entering the trunk and getting soaked up by the thick insulation attached to the carpet which could cause mold/ mildew.
After this cover is carefully removed it will look like the picture below.
The next step is to remove the fuel lines from the sender assembly. To do this you need to use the pliers to depress the plastic tangs at the end of the line and pull the lines from the assembly. Keep some shop towels around to soak up the fuel that will leak from the lines. After the lines are taken care of then you need to remove the Two electrical connectors. One is for the Fuel tank pressure sensor and the other is for the fuel pump and level sender.
After everything is removed from the top of the sender then comes the fun part. The lock plate will most likely be rusted to the tabs on the tank and it will need to be hit a lot to get the plate off.
After you remove the lock plate from the fuel tank the Fuel sender assembly can now be pulled out of the tank. Keep in mind that the assembly is filled with gas and should be tilted on its side over the tank to let the gas drain back. otherwise it will spill all over the place when you start to work on it.
This is a picture of the assembly once it is pulled from the tank and drained of fuel.
The next step is to un-clip the electrical harness that has the wires for the sender and fuel pump from the whole assembly. Then it is time to un-clip the sender from the assembly by depressing the two tabs that hold it in place and sliding it off grooves that it sits on.
Once you have the sender off the assembly then it is time to remove the float from the sender. It is held into place by tabs on the little arm that is going to be replaced. Just pry it off with a small screw driver being extra careful not to bend the float. if this gets bent than it could potentially cause an inaccurate gauge. Once it is removed it will look like the picture below.
Now it is time to remove the arm from the sender. Balance the front of the sender on the two sockets and use a screwdriver and the hammer to tap the pressed in brass retainer. Be careful and take your time since you are just replacing the arm you don't want to damage the scale that the resistors are on or else you might have to get a whole new sender.
After you remove the old arm now it is time to do the same thing with the new sender. Be extra careful with the new part because you don't want to disrupt the new contact points. After you have both parts removed compare them side by side to verify that they are the same part. You will also notice the extreme difference in the contacts.
After you verify they are the same part now you need to install the new arm on the sender. To do this just balance the back of the sender on one socket under the brass retainer and use the screwdriver and hammer to tap it in place. Tap it enough so the arm can move freely while also making sure the contacts are touching the resistor scale at all times. After the new arm is installed it will look like this.
Now all you have to do is put the sender back on the assembly and connect the harness and put the assembly back into the tank. After you have completed the repair verify that the new part fixed the inaccurate or fluctuating gas gauge.
Although this fix will work on fluctuating gauges it may or may not work on a gauge that is stuck at full or empty. In my case after i had performed this service my gauge still was at the full position.
If this repair does not work then it is time to get into the electrical diagnosis of the whole fuel sender circuit. Below is the diagram of the circuit
In this circuit There are two basic wires going to the fuel sender. There is the Purple wire ( PPL) and there is the Black and white wire ( BLK/WHT). To test these wire to make sure they are in good condition you should test the resistance of them to ensure they will carry the current that the computer sends it. To do this effectively you should remove the cowl above the Instrument cluster to gain access to the Cluster harness/ connector. Disconnect the connector on the right. it should look like the diagram below
** DISCONNECT BATTERY BEFORE USING OHM METER**
Now use a pin to back probe terminal C2 which you will notice is the purple wire that is coming from the sender. After this terminal is back probed now you need to back probe the connector in the trunk. And using an Digital Multimeter on the OHM function measure the resistance of this wire.
The resistance of this wire should read 0000 OHMS if it is in good shape. next do the same with the BLK/WHT wire that goes from the sender to the cluster. The wire on the connector to the cluster is terminal C13. This wire should also read close to 0000. If these wire do not read 000 then that means that there is a restriction in the wire that is causing it not to allow current to flow. The solution is to follow the wire from the sender in the trunk back to the instrument cluster and observe if there is any obvious problems that stick out. such as corrosion or a broken wire. But if these wires prove to be good and the sender in the tank is good than the problem is probably in the instrument cluster and can only be solved by replacing the cluster.
My Findings:
After i replaced the sender arm in the tank my gas gauge was still stuck in the full position. And by looking in the tank with the sender assembly out i knew there was not much gas left in the tank. So i tested the resistance of the PPL wire and the BLK/WHT wire
These were my results:
PPL = 1.994 Million Ohms of resistance
BLK = 3.00 Ohms of resistance.
So obviously there was something wrong with the purple wire. The black wire i figured 3 ohms wouldn't make the big of a difference so i didn't even bother looking for the cause of that resistance. So the next step i took was to follow the PPL wire from the fuel sender, and right away i discovered the problem that was causing the high resistance. The wire had rubbed against the under body of the vehicle for so long that it actually caused the insulation of the wire to wear at that spot. and as water found its way on the copper it corroded the wire so badly that the wire was only held together with green dust. After cleaning up the wire and crimping the two ends together i then tested the resistance of the PPL wire again, Except this time the resistance was a perfect 0000. So after i put everything back together my gas gauge was working again. Although it said i only had 2 gallons left i then went to the gas station to top it off and it took exactly 16 gallons to make a complete 18 gallons which is the specified FULL amount.
I hope this write up can be helpful for those of you that have lived with the faulty gauge and have found no solution to the problem.
EDIT; pic resized
1920x1080 Good Job!