does your fuel pump have to be on a relay or can you just have it on a switch on/off?

You will melt the switch... that's why the relays are there

You can get switches heavy enough for this, but as said relay is easier.
tabetha

You wont melt the switch.It all depends on what switch you buy. But most of them wont melt. So yes it can be. I am going to do it. The best one is one of those "nos" switches. They are good and can handle the current. Cos it isnt much.

Any DC current IS a lot, and a LOT harder on switches than AC current.
tabetha

>>>>>>>They are good and can handle the current.<<< MR JeroentjeRS
YOU HAVE JUST ANSWERED YOUR OWN REPLY MATE!!!- IF YOU WAS RIGHT NO CARS WOULD USE RELAYS!!!!!!!!------------------ IF IT USES A RELAY -USE A RELAY!!!

Didn't say that mate. It would be stupid to use a on off switch in a factory car would it? The guy asked if it has to be. Awnser is yes and no. They use relays on fog light these days. But it wasnt always like this was it? So yes it is better to use a relay cos its std like this. No reason to remove it. Then again if you don't have one in a cross car or something like that. A switch can be used. So i didnt say don't use the relay cos a switch is better. Read before you post something

The POINT of WHY they use a RELAY is due to COST, pure and simple, a RELAY is CHEAPER than a SWITCH THAT IS HEAVY ENOUGH to carry the same current.
Relays cannot be used in some circuits(not cars) due to NOISE they create electrically.
POWER STATIONS, still use KNIFE SWITCHES, these carry MILLIONS OF AMPS, the sort you see in old black and white FRANKENSTEIN FILMS, they spark like buggery when switching, but on a car it is due to cost nothing esle.
tabetha