Causes of excessive fuel consumption

Some possible causes could include:

1. A malfunctioning oxygen sensor: The oxygen sensor measures the amount of oxygen in the exhaust and sends this information to the engine control module. If the oxygen sensor is faulty, the engine may run too rich or too lean, which can result in excessive fuel consumption.
2. A clogged air filter: A clogged air filter can restrict airflow to the engine, causing it to work harder and use more fuel.
3. A faulty fuel pump: If the fuel pump is not working properly, it may not be delivering an adequate supply of fuel to the engine, causing it to consume more fuel in order to compensate.
4. A leaking fuel injector: A leaking fuel injector can allow fuel to escape from the engine, leading to an increase in fuel consumption.

To determine the cause of the excessive fuel consumption in your Mazda Demio, it is best to have it diagnosed by a mechanic. They will be able to perform tests and inspections to identify the problem and suggest the appropriate repairs.

You can overinflate your tires by a few psi over standard, not use AC, avoid stop and go driving and jack rabbit starts, remove unnecessary heavy objects from car, keep max speed around 55, proper oil level, no brakes dragging, anticipate stops and let off gas, etc.

change fuel filter + clean egr valve

The computer will very likely be generating engine fault codes if you have quite excessive consumption and there is no point in guessing what the problem is as there can be numerous causes. You have not mentioned if you have a check engine light showing but if you don't just yet you soon will if the problem persists.

1. Go to a reputable mechanic and have the car scanned for fault codes because it will be very likely throwing some codes if you are having a high engine fuel consumption issue (as opposed to a loss of fuel from the fuel system due to an external fuel leak).

2. On thing you can do yourself is remove the old dusty air filter element in the air intake box ( which no doubt has not been changed since ????) and put in a new OEM air filter unit. A dirty clogged unit will cause your engine to run poorly.

How to open

Check or have checked the O2 sensors for reading false lean causing a constant over rich running condition leading to higher fuel consumption.

Emissions System not functioning properly can cause excessive fuel consumption. Emission System Evaporative Canister is likely clogged this will cause both oder and excessive use of fuel.

Hi, Lee,
you have lose earth connection somewhere.It is difficult to find.Can be anywhere.

have you checked your tires? a low tire will cause fuel consumption

Brakes could be binding or hand bake cable holding on but you think youd smell burning brakes if that was the case!What condition is the oxy sensor in ,maybe carboned up and contaminated which can tell the engine management to supply more fuel than required.is the air filter air box in good condition and air box lid securely fastened.Should be sealed from air box to throttle body If the air filter is clogged and dirty that can lead to excess fuel consumption.Have you installed any injector cleaner in the fuel tank.cleans up dirty injectors thst can cause excess fuel consumption.