Petrol gauge

[Fayjoe]

Hi I have a 20 year old Yaris that I love. Recently I am putting petrol in my the gauge starts flashing. I have put £20 Friday and only done 10 miles and it’s flashing. Could there be a fault? Thanks 

[flash22]

Faulty gauge, sender, a fuel leak or someone is syphoning your petrol

[Cyker]

My diesel one started getting weird fuel gauge issues before I had to get rid of it for the ULEZocalypse - It was like the sender was getting stuck and wouldn't report the fuel level properly past a certain point. I took it out and cleaned and checked it but couldn't find any problems (Arm moved freely, resistance changed properly etc.). Was going to replace it but figured there wasn't any point since I had to change cars anyway.

The sender is incredibly easy to access on the Yaris Mk1 - You just slide the rear bench all the way forward, then fold it up and lift the carpet and there it is! I loved how easy it was to work on that car  

Just make sure you have lots of sacrificial towels ready or something as the fuel pipes hold a fair amount of fuel and it goes everywhere when you remove them!!

[Stevie J]

Old Mk1 models were prone to the metal fuel filler neck pipes rusting through due to them being exposed to water and spray from the passenger side rear wheel. When I had a mk1 about 10 years ago, this pipe rusted through, and its breather rusted through into a massive hole behind the filler cap as well. If this pipe is rusted through badly, it would be possible for fuel to leak out when going round sharp bends in the road - but if it was this severely holed, you would likely smell petrol from the area around the back corner of the car, and it may possibly leak through when filling the car using the pump at a petrol station. 

Check the filler neck pipe, and its smaller breather pipe which runs alongside it, from the fuel tank to the filler cap thoroughly before condemning the fuel tank sender unit. If the filler neck pipe is OK with no holes through corrosion, then it is, as said above, likely to be a problem with the sender unit in the fuel tank giving incorrect data to the LCD display cluster in the dashboard.

[Cyker]

Good shout, hadn't considered that! Might be able to look at that from under the back with a torch, but can't remember if the wheel well liner obscures it or not on the Mk1. At the very least should be able to smell it...!

[Stevie J]

On my T reg 1.0 CDX 5 door (that I owned between 2011 and 2016) there was no liner to protect the filler neck pipe at all - easy to see from under the wheel arch, and the fact that there was no protection for this pipe is one of the reasons they rust through. Not good either when they do rust through as water and spray can get into the fuel tank through the exposed rust holes. Fortunately though I suspect that a good many of these damaged pipes will have been picked up at MOT inspections and the issues sorted out before they get really severe, but the rust holes can form on the upper side of the filler neck pipe, well up into the top of the wheel arch and may not be picked up by an MOT tester. On my own car, it was about 12 years old when we found the holes in the very top of the neck pipe and its breather pipe too, but left longer, this would have get worse quite quickly.