Why Petrol Pump Called Petrol Pump, Not Diesel Pump? Know Here

There could be two possible explanations for this. The first is that historically, petrol (or gasoline) was the main fuel used for vehicles when these stations first became common. 

Also, you may be aware that petrol cars always outnumber diesel cars. Thus, they are more popular. Therefore, the name "petrol pump" stuck among us even though currently these pumps also dispense diesel as well.

It's similar to how we still call certain things by their original names, even after they evolve to include other functions. Like, for brushing teeth, many Indian households still use the term 'colgate' and how 'Fevicol' became synonymous with adhesives. 

The second reason could be, that petrol, diesel or CNG are extracted from crude oil which is also known as petroleum. Thus, the name petrol pump became widely popular.

However, in some countries, petrol pumps are also called gas pumps, fuel dispensers, fuel stations etc.