Fuel Gauge Reading Problems

[mr299ron]

My fuel gauge only reads above half at any level above half. e.g. If I stick a full tank in gauge reads half. If I stick 3/4 in it still reads half.

Once the tank is physically only half full and under it will read less, properly. However, it won't read on empty once I'm on empty. I actually ran out of fuel because of this.

Also, the empty fuel light seems to always be on. This can be when I have half a tank, half a tank, half a tank, and a little less than half a tank.

Where is the fuel gauge sensor/reader and is it a total xxxx of a job to replace?

[bobhatton]

My fuel gauge only reads above half at any level above half. e.g. If I stick a full tank in gauge reads half. If I stick 3/4 in it still reads half.

Once the tank is physically only half full and under it will read less, properly. However, it won't read on empty once I'm on empty. I actually ran out of fuel because of this.

Also, the empty fuel light seems to always be on. This can be when I have half a tank, half a tank, half a tank, and a little less than half a tank.

Where is the fuel gauge sensor/reader and is it a total xxxx of a job to replace?

Just remove the tank and fit new gauge sensor.

[Pauln]

You don't need to remove the fuel tnk to change the fuel level gauge sensor. It's actually accessible form inside the cabin.

Just remove the ash tray and ash tray holder and you will see an inspection panel with a couple of cables coming out with connectors on the end. Unclip these and remove the inspection panel.

Below this is a circular panel which is the top of the sender, unscrew and remove the sender. It can be a bit of a juggle getting the sender out, but it will come.

Obviously make sure you do this in a well ventilated space or the car will quickly fill with petrol fumes.

The fuel level meter sender is just a simple variable resistor linked to the float arm. Usually all that needs doing is a light cleanup of the wire wound variable resistor with some fine wet and dry to get it to read accurately again. If you have a multimeter aim for readings of something like 3 ohms with the arm raised(full tank) increasing to around 110 Ohms arm fully lowered.

You'll need to gently bend back the tabs on the folded metal cover over the wire wound resistor to gain access once you've removed the sender from the car. It's all pretty straightforward.

But the low fuel level warning light is controlled by a different sensor attached to the assembly. If that's on all the time that sensor is probably blown, and I don't know of any doges to fix it. Mine went following a long layoff with low fuel tank.

I just fitted a second hand assembly from fleabay, having cleaned and checked the variable resistor first.

Paul

[rgb]

pauln is right but sometimes the fuel gauge gets messed up when people fit lockwood dials and move the needle.

[Pauln]

pauln is right but sometimes the fuel gauge gets messed up when people fit lockwood dials and move the needle.

Too true, and not just the fuel gauge

Spent ages trying to work out why my turbo had a high idle speed. It didn't actually, the previous owner hadn't fitted the tacho needle back correctly when he fitted Lockwood dials.

Just add injury to insult, he also fitted blue leds at the same time, so all the needles were actually invisible at night

But that's OT.

[masterbateson]

pauln is right but sometimes the fuel gauge gets messed up when people fit lockwood dials and move the needle.

Too true, and not just the fuel gauge

Spent ages trying to work out why my turbo had a high idle speed. It didn't actually, the previous owner hadn't fitted the tacho needle back correctly when he fitted Lockwood dials.

Just add injury to insult, he also fitted blue leds at the same time, so all the needles were actually invisible at night

But that's OT.

This is a problem I've got with mine, speedo reads about 10 mile per hour out so 40 in a 30 and fuel gauge never goes up to full when I've filled the tank fully up.
How I'm going to get the needle for either back in the right place I'll never know.
And I bet trying to sort this out with your RPM is nigh on impossible I mean how on earth would you know what your engine is idling at?
You could just assume your car is set up to idle at right speed/rate but its not guaranteed.

[Pauln]

If you're lucky and have a steph delimiter fitted to your speedo you can use its built in "test sweep" facility to check the speed displayed is accurate and adjust the needle if necessary. Otherwise the only way I know is "trial and error" adjustment comparing the speedo readout with that on a sat nav.

To adjust the tach I borrowed a dongle that you can plug into the diagnostics port to read out the actual rpm info supplied to the ecu via a bluetooth connection to an app on your mobile or tablet. etc



There's more info about this method in my Profile Thread

Back on topic, in the case of the fuel gauge you first need to take the sender out as discussed above. Then use a multi-meter to check for the correct resistance at both ends of travel of the float.

If the readings are out, lightly clean the wire wound track of the variable resistor which is inside the folded metal cover on the sender assembly (carefully bending back the tabs).

Once the readings are within spec (around 3 ohms with the arm raised(full tank) increasing to around 110 Ohms arm fully lowered) you can then test if your fuel gauge needle reading is correct.

Put a temporary cover over the open panel in the fuel tank to try to stop petrol fumes entering the car and make sure the car and surrounding area are well ventilated to clear any existing fumes.

With the sender still removed from the fuel tank reconnect the wiring to it and hold the float at the top of it's travel.

If you now turn the ignition to ACC, you should see the fuel gauge needle slowly rise, and I mean slowly. Creep is probably a more accurate description. The fuel gauge should eventually come to rest on full. If you then turn off the ignition and lower the float to the bottom of it's travel, when you turn the ignition back to ACC the needle on your fuel gauge should eventually drop down to empty (or below).

If all is well turn the ignition off, and carefully replace the sender in the fuel tank.

If using this method this please be carefully. The last thing you want is to create a spark when there are petrol fumes around.

Paul