After filling up my 2003 Transit campervan with diesel the other day, I noticed that the fuel gauge was very slow to respond: after 10 miles it showed 3/4 full, but eventually came up to the 100% line. It hasn't done this before. Is there any cause for concern?

In case it changes anything: this was the first time I'd filled it up in about 6 months. I only drive about 50 miles per month regularly, and couldn't even do that over summer because of an injury. I normally fill up when it gets to about 1/4, but left it until about 1/8 because I was hanging on for somewhere cheaper.

  • 1
    I would have liked to have kept a closer eye on it to see whether it crept up or went up in little steps, but I needed my eyes on the unfamiliar roads.
    – Chris H
    Nov 5, 2019 at 12:52

2 Answers 2


There's 2 possibilities here. The first is that you have an electro-mechanical fuel quantity meter, and that it may be sticking a bit due to a lack of movement. The good news is it did eventually react, and hopefully it will go back to normal. As long as it shows the fuel level accurately it doesn't matter if it moves a bit slow, the major concern is that sticking may eventually lead to failure. I would do nothing at the moment, just keep an eye on it and reset your trip odometer every time you fill up as a backup to the fuel gauge.

The other possibility is that you had a weak battery, and that was causing the gauge to show low. As you drove the alternator charged the battery and the gauge went back to normal. This is a real possibility as you are not driving often. If the battery is old it may need replacement, if you are driving once in a blue moon a trickle charger would be a good idea to keep it charged when it is not in use.

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    I suspect the former. Transits used fairly old technology even for the time they were built, but mainly because I was well on the way through one of my occasional longer trips so had done a few hundred miles in the preceding few days. As it had sat nearly full for several months sticking would seem plausible.
    – Chris H
    Nov 5, 2019 at 12:46
  • That would suggest that I need to keep an eye on it to make sure it drops roughly as expected; the trip meter already acts as a backup (I know my typical fuel consumption well enough and reset it every time I fill up), and not worry beyond that.
    – Chris H
    Nov 5, 2019 at 12:49
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    Exactly @ChrisH, it's not going to affect how it runs, so as long as you keep an eye on it you should be fine.
    – GdD
    Nov 5, 2019 at 12:55

In the fuel gauge, they use a potentiometer to measure the amount of fuel (For simplicity: Something like a thing seen in flush tank, connected to a volume control in radio or something). So it take a little time to raise. In your case there must be a problem(may be electric or mechanical).

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