Mod Details

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This page covers all ICE cars. It’s more generic help and some parts may not relate directly to certain models but it’ll give you an idea of where to look and what to try.

My Fuel Pump Stopped Working

The knee-jerk reaction is to just think that the fuel pump has failed. In my experience, there are several other things that are far more likely. Yes, fuel pumps can fail. Normally due to water in the tank causing corrosion. However, it’s much more likely to be one of the following issues.

Fuses

Check all of the fuses to be sure but for example, the fuel pump fuse is:

450 (600cc) – lower fuse box, fuse 2.
450 (700cc) – fuse 16.
451 – fuse 16.
452 – fuse 16.
453 – rear fuse box, fuse 3.
454 – fuse 11.

Relays

Only the 600cc fortwo and 454 forfour had relays that could be changed.

450 (600cc) – Lower fuse box, relay K1.
454 – C and K.

All other models had relays soldered directly to the PCBs inside the SAM unit. There have been instances of them failing but it’s very rare.

Earth Connections

For a pump to function, it requires power and a return to ground. You can have all the power you like but if it’s not making a return path back to the battery negative, it’s not going to work.

Earth points can be found around the car. They are lugs bolted directly to the car’s body, usually with several brown cables coming from them. I have listed the Roadster earth points here. Other models are similar.

Check the grounds are connected securely, all of the wires are connected to the lugs and there’s no damage to the wires.

Damaged Wire

Get your multimeter out and continuity test the wires from the fuel pump connector to the SAM unit connection and the body earth.