Ask the Mechanic: Why is my fuel gauge not working?

Please help diagnose my Belta 2001. The fuel gauge does not work. Wiring mechanics have been unable to solve the problem. Sometimes the tank shows it is full, other times it indicates that it is empty even after fuelling. Mechanics have even changed the dial to no avail. What could be the problem? 


Hello Anne, it is very uncomfortable to drive while you are guessing how much fuel you have in the Toyota Belta fuel tank. Fuel gauges fail when they give wrong fuel level readings or no readings at all.

The four common causes of fuel gauge failure on your Toyota include a faulty fuel sender attached to the fuel pump, corrosion damage or kinked fuel sender circuits or connectors, a faulty fuel gauge dial or damaged instrument clustre which houses the fuel gauge. It seems your mechanics have only looked at the fuel gauge located in the instrument clustre.

They need to check the other components of the fuel metering system of your Belta. The fuel gauge (dial as you call it) in the instrument clustre works in tandem with the fuel level sender unit which is in the fuel tank and reads the fuel level using a floating device. They are both electrical devices with power supply, integrated circuits and mechanical components that can fail due to corrosion, kinking or breakdown due to ageing. A damaged instrument clustre or broken circuit will affect the fuel gauge, which can be inspected as well. One of the four usual suspects will be the trouble causer.


I recently bought a 2008 BMW X5 3.0 diesel. Few months after purchase, its belt tensioner got damaged and the external pulley part fell off. I have never seen this part fall off any other car. Is this a common problem with BMW X5? Is this a reliable car and what should I expect in future?


Hello David, the engine V belt tensioner and its pulley on your BMW X5 E70 engine, just like other car engines, works hard. It tensions the V belt which pulls different engine accessories such as the water pump, alternator and steering pump and works in a very hot condition which makes it susceptible to mechanical wear and damage overtime.

A V belt tensioner and pulley failure does not make your BMW E70 or any other car unreliable.

The V belt tensioner and the attached pulley is an engine component that is expected to fail and should be replaced during maintenance checks in accordance with manufacture recommended maintenance schedule or when it shows signs of ageing.

To avoid unexpected failure and getting stranded, pay attention to squeaking or rattling noises from the tensioner pulley or unusual tear of the V belt both of which can be a result of a failing V belt tensioner and its pulley.


I have a Toyota Picnic 2000cc 1AZ-FE engine but it has low power when going uphill and also hesitates when accelerating. I have tried cleaning the throttle body, MAF and oxygen sensors without improvement. Also, fuel consumption is high, averaging 8kpl. I am thinking of finding a suitable modern engine that can swap directly with the 1AZ-Fe. Please advise.


Hello Daniel, your Toyota Picnic 1AZ-FE engine loss of power may be caused by reduced fuel pressure or a dirty and clogged Exhaust Gas Recirculation (EGR) valve. Ample fuel pressure is essential for optimum engine power. If your fuel system filter located in the fuel tank is dirty or clogged, it will reduce the fuel pressure and start to damage the fuel pump.

It is a good idea to check the engine fuel pressure using a fuel pressure gauge or diagnostic computer. If the current fuel pressure values are lower than the recommended values, consider renewing the fuel filter or replacing the fuel pump. Should the fuel system be okay, then check the EGR system.

The EGR regulates flow of exhaust gases into the air intake system. This helps improves engine efficiency, fuel economy and reduced emissions. Overtime the EGR valve may fail due to clogged soot.

This will reduce engine power and performance. Check those two areas before you look for another engine.

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