Citroen C3 Owners

Hey guys wondering if anyone can help, have a 1.4 mk1 c3 with a voltage drop at the fuel pump, have changed fuel pump and have got a good earth, any ideas?

Hello Babychaz07

When you say a voltage drop can you explain please. I'm guessing you're measuring the voltage across the pump?

What is the voltage you're measuring?

Apart from you're measuring the voltage drop, is there a problem with the pump and how it's working?

And finally, have you measured the voltage on the wiring at the pump with the pump disconnected?

Babychaz07 wrote: ↑Wed May 15, 2019 1:23 pm have changed fuel pump and have got a good earth, any ideas?

I wouldn't advice changing the pump until it was tested and found to be faulty.

You checked for a good earth,

but did you check for a good +12v supply?

Missing Lincs wrote: ↑Wed May 15, 2019 2:47 pm Apart from you're measuring the voltage drop, is there a problem with the pump and how it's working?

It does seem like we only have half the story.

Car wont start, will turn over but not start, battery has been charged, fuel pump works, drops by 2volts at fuel pump. Sorry not very good at explaining

Babychaz07 wrote: ↑Thu May 16, 2019 9:26 am Car wont start, will turn over but not start, battery has been charged, fuel pump works, drops by 2volts at fuel pump. Sorry not very good at explaining

It sounds like an IMMO - immobiliser fault.

Try the other key will prove that one.

But you also get this with crank/cam sensors and a broken (sheared) cambelt

Read the codes with a cheap OBD2 reader from here


and it would be worth checking if the cam belt is due for service.

C3CAR wrote: ↑Thu May 16, 2019 3:41 pm

Babychaz07 wrote: ↑Thu May 16, 2019 9:26 am Car wont start, will turn over but not start, battery has been charged, fuel pump works, drops by 2volts at fuel pump. Sorry not very good at explaining

It sounds like an IMMO - immobiliser fault.

Try the other key will prove that one.

But you also get this with crank/cam sensors and a broken (sheared) cambelt

Read the codes with a cheap OBD2 reader from here


and it would be worth checking if the cam belt is due for service.

Unfortunately I only have the 1 key have had car plugged into a snap on reader and no codes came up so I'm really at a loss

Babychaz07 wrote: ↑Thu May 16, 2019 3:45 pm Unfortunately I only have the 1 key have had car plugged into a snap on reader and no codes came up so I'm really at a loss

Snapon is not well known for doing well with the finer points of the C3.

If you want to check IMMO problems, I would recommend lexia/diagbox - or a trip to the dealer that uses the same equipment.

One key problems crop up quite often and I have never worked out why anyone would buy a C3 with only one key, considering this is all there is to open it and start it.


If you get 'no faults' then you may have a blown fuse to engine ECU, check the BSM fuses including F3.