Update On E39 Starting Problem

[boatman]

Hi folks,a couple of replies to my last entry mentioned the fuel pump relay which I thought could be the answer so I replaced it a couple of days ago also tried to check wiring everything seems ok but I havent tried any meters not sure how.The problem is no better you switch on either first thing or after the cars been stood a while as soon as I switch on if I can't here the underfloor pump I know it won't start then after a few tries the pump can be heard and it fires up no problem once its running it does'nt miss a beat seems worse if its wet the cold does'nt seem to affect it,its a shame because its putting me right off don't trust it any more

[Guest Mister Dabsy]

Wish I was there to nail it for you...

My fuel pump buzzed for 1 - 2 secs just to prime, couldn't hear it after that (before starting motor) !

Just wondering whether the fuel-pump's internals are dodgy ?!

[Bizeebmw]

Have you tried the ignition switch? It's mounted behind the key barrel. Costs about £35 and take 30 mins to fit. Most common fault with e39 non start. If not get it in a diagnostic machine, only safe way to diagnose it without shovelling more money in.

[boatman]

just thinking if its ignition switch why does it only do it first thing or when its been stood a while,think maybe diagnostics is the thing is it possible to plug a lap top into it if you,d got the right lead.Thought the other day it had improved since it warmed up but the last two days have,nt been all that cold and its took a few minutes trying to get it to start,got a mate whose a bit good with diagnostics maybe I,ll have to admit defeat and go and see him.On the subject of the pump buzzing for a long time yea I,ve wondered about that never really waited to see how long it lasts you,d think it would only work a few seconds till it needed more fuel