Hi Everyone,

I just wanted to bump this thread as I’ve just dealt with this very frustrating intermittent fault. My symptoms were identical to those described here. The car would crank all day long (if the battery had the charge) but it just wouldn’t start.
Then after 10 minutes or, most 3 days, the car would randomly fire up again and run perfectly. One time I was stuck at a petrol station and had to call the recovery team to collect me; as soon as they arrived, they tried the key and the bugger started first time.

In amongst this, I took a number of steps to resolve the issue, felt like I’d got there every time until the car wouldn’t start again 3 weeks later. Scanning the car with icarsoft and carli only said the vehicle had no fault codes”. So I was a bit stuck.

I then had to go through a number of trial- and- error procedures to narrow down the problem. I began with all the fuses.tested every one with a multi meter- all good. Then I found the elusive fuel pump relay (on the other side of the glove box fuse box in my model) and swapped it with the horn relay. No luck there.

Next, I decided to inspect the fuel sender (found under the rear passenger seat, drivers’ side on UK models). Hooked this up to my 12v drill battery and all was fine. As my car has done 150,000 miles I looked into whether I should replace this anyway as a serviceable item while the car was apart. I decided to replace this although I now know that it probably would have been fine for a few more k. Changing this part is very easy and there are a ton of videos on it. Just make sure the fuel tank is not full if you can help it.

Anyway, this didn’t solve my problem as another 3 weeks down the line, my non-start was back. So now wondering if the non start could be an immobiliser issue or a cam/crank shaft position sensor issue. Speaking to some specialists told me that cam/crank sensors typically throw a code, and I had none. I checked for water in the e-box in case this had shorted the anti-theft circuit- nothing wrong there.

Then, at last, my intermittent fault turned into a permanent fault and wouldn’t start. I was actually glad because it meant if I fixed it, it would stay fixed and if I didn’t, I was in for the big bucks. Then I remembered reading about the pre-supply fuel pump (alternatively called the in-line fuel pump).

I didn’t want to get into the habit of just changing every part conceivable, but I had no codes and couldn’t work out a way to see if fuel was getting to the injector. Therefore, I bough my a £30 online pump from eBay with the reasoning that I’ll try that as a last resort before getting it towed to a bmw specialist - something I know would end up costing me thousands.

This was easy enough to change, but getting the panelling out the way is the frustrating part. The in-line pump is located next to the diesel filter on the underside of the car. Directly underneath the rear passenger-side seat.

Anyway, this sorted all of my problems and the car is now running beautiful again!

I must add that I’m not trained in anyway and so I’m sure have made mistakes and/or wasted my time,, but I do like to save myself pennies here and there by fixing issues like this myself. Just thought I’d post this in case anyone else may benefit.

2004 3.0d E53