Random no-start

[Reggit 0]

I've got this random non-starting problem which is gradually getting worse;

 

The engine turns fine but just won't try and fire. No relays click when cranking. It will eventually start after multiple attempts if the battery holds up that long. Once it does start it runs fine. (I've had a no-start issue before, but that time a relay was chattering whilst it was cranked - this one's different.)

 

Today it played up and I noticed that the fuel pump didn't appear to prime. After about 4 seconds of the ignition being turned on a relay clicked (pump turn off signal?), but no whine from the pump.

 

Is the prime cycle controlled by a different circuit than the constant run cycle?

 

The car runs fine usually, just has this annoying non-start issue, then it's fine when it eventually start.

 

I'm wondering if it is the pump going weak as I can hear it whining if the parcel shelf is removed.

 

Before anyone suggests it, the ignition switch has been changed with a decent geniune VW one.

 

If anyone's got any ideas I'd be grateful - the wifes hinting at getting something reliable (and boringly mundane!)

 

Cheers.

[Supercharged 2]

Must be Fuel pump relay if not priming, I'd replace this and do the ECU one at the same time.

[Reggit 0]

Good call - changed the relays and it has been starting reliably again. Thank you. :thumbleft: