I have long wondered what kind of gremlin is sitting behind the functioning (or lack of) of my fuel gauge. I've read all about the issues with fuel senders from various sources and know there is no holy grail of a product, especially if you are running the stock system of a sender next to and separate from the fuel pump.
It was a nice Sunday morning, early, everyone else in the house was still asleep, so I decided I would get up and attempt an investigation and maybe even possibly resolve it. I dared to dream!
I first had to empty all my back up tools and parts that go everywhere with me to get to the tank area beneath the boot/hood space.
Once in the boot space and with the spare wheel removed, I unscrewed the access panel to the fuel tank.
Googling helped me find the following troubleshooting article which I followed: https://support.delorean.com/kb/a63/fuel-sending-unit-gauge-oem-style.aspx
The Sender unit is next to the fuel pump, to the right in the above photo. It is connected via a three pin connector comprising a light green/orange, black, and a green/black wire as shown in the photo below.
In order to unscrew the sender's retaining cap to remove the sender unit from the tank, I first needed to unclip the three-pin connector.
After removing the sender from the tank I tied the connector ends up to ensure they didn't get lost beneath the tub and then reconnected the three-pin connector to perform the tests.
I first of all tested the empty position by positioning the sender upright so the float falls to the bottom. It should show empty on the fuel gauge and the fuel empty light on the instrument cluster should illuminate. As can be seen below the gauge correctly read empty but no light came on.
Next I inverted the sender unit and heard the float slide to the opposite end. This should replicate a full tank scenario, the gauge should read full. As seen below this correctly happened, well more or less, given some patience I could have waited to see if it completely rose to the full position.
So as per the instructions in the guide, I further tested to check if it was the gauge itself by disconnecting the three pin connector and turning on the ignition, the fuel needle should shoot straight up, which it did, as shown below.
Then I unscrewed to sender unit to check for debris affecting the float.
Before putting the unit back together I also unscrewed the central shaft from the top to expose the sheathed inner part (sorry no photo of this). There wasn't anything obvious to tend to on this part, but I gave it a shake and let the excess fuel evaporate before putting it all back together and fitting the entire unit back into the tank and attaching the connector. With hindsight it occurred to me that surely the inner workings should be sealed within the central tube and as such there shouldn't be any fuel in there. Could this be what had been affecting the fuel gauge readings? I'd be interested to receive your feedback.
Next I turned the ignition on again and the needle rose from empty to just 1/8. I decided to give the car a spin and also fill up so I drove to my local petrol station. After fuelling I got back into the car, started the engine and the fuel gauge needle shot straight up, past the full (one o'clock) position to a twelve o'clock position (just as in the photo before last).
During the journey home the needle moved from the 12 o'clock position to 3/4 full as I went up hill and back to 12 o'clock as I levelled off, or went downhill.
The end result of this Sunday morning's activity has been somewhat of a success in that I know have a fuel gauge that registers something near to a full status and doesn't just go from empty to 1/4 full. However if the linked instructions above are correct, the tests conducted indicate either the contacts in the sender that activate the fuel empty lamp are corroded, or that the bulb in the instrument cluster is faulty. I will add the checking of the bulb to the to-do list since the sender is what it is!
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