Fuel Pump keeps dying ? Help

Tue Sep 08, 2015 4:31 pm

Ok, so my 318i m40 was refusing to start last few weeks.

Diagnoised it to be the fuel pump as there was a faint buzz from the pump.

I purchased a non oem replacement last week, it worked great, fitted it to the car and the car started, lasted a few hours and the same thing happened, no power at all from the pump now.

What could be causing the pumps to fail ? or is it just a mad coincidence.

I also checked if the DTM and Fuel Relay was clicking once power was applied and the both did. Also tryed a 12V Power Supply from a car battery charger to test if it was the car battery at fault.

Starting to become clueless at this stage.

Any help appreciated.

Tue Sep 08, 2015 4:43 pm

Is there power at the new pump but the pump is not running?

Could be a duff replacement.

Tue Sep 08, 2015 4:47 pm

Is the tank full of silt or rust?

Tue Sep 08, 2015 5:51 pm

Theres power going to the pump. The pump started gradually losing its healthy buzzing noise and eventually just stopped working. The tank has fuel yes, however the replacememt pump came with no filter.

Tue Sep 08, 2015 6:33 pm

Has it got a filter on it?

Tue Sep 08, 2015 6:35 pm

Is replacement new or second hand?

Tue Sep 08, 2015 10:00 pm

Replacememt was new. And it had the old filter on it but with pulling the pump out it wasn't on then so it could have sucked up old dirt. I also read somewhere about a power surge through the alternator or a bad earth. I did have my suspensions about The battery but I didn't Want to waste money changing it. Thanks Again so far for the input guys

Tue Sep 08, 2015 10:25 pm

Shiz wrote: I also read somewhere about a power surge through the alternator or a bad earth.

Either you've misinterpreted what you read, or it was complete rubbish!
Filter is important, but unless your tank is badly contaminated with dirt, it's unlikely to be the problem, as the pot in the tank where the pump draws from is continuously flushed by filtered fuel returning to the tank from the fuel rail.
Either connect a 12 volt bulb directly across the pump plug terminals, so that you can see if the pump is not running, but still getting power, or arrange a 12 volt feed to the pump, via a 7.5A fuse and a switch, directly from the battery or lighter socket, and see if the car behaves with the pump connected like that.