What's that noise when I switch on the ignition?

[KTiM]

I've always heard a noise that I would describe as sounding like an electrical motor working for about two seconds when I switch on the ignition. I switch the ignition on today and for the first time didn't hear the noise and the car wouldn't start. So, presuming that the absence of my noise is connected with the failure to start, can anyone tell me what that noise is/was and how can I get it back? (car is a 450 SE)

[barrington]

its the fuel pump if you look infront of the driver rear wheel under the car you will see it on a plate with the fuel filter

[350zwelgje]

Agree with previous post, would think it to be petrol pump linked (relay/fuse/pump itself) as well. Pump operation depends on the car you have. Mine doesn't pump until engine is cranking, but it is only a humble 350i.

Test with two leads directly from the battery, and even reverse the connections. But if the pump springs to live on reverse, it could be dead within a short time due to debris that will kill it as that would be it that it stopped working in the first place.

Rob

[dougc]

Definitely the fuel pump. Test it out as suggested but don't rule out a simple electrical fault. When mine went it turned out to be an immoliser problem. Check all the fuses first.

[The Colonel]

Tim
Just a long shot this - but have you been fiddling under the bonnet just prior to this? Might be worth checking the fuel cut out switch (small black box which has a manual push / pull knob on it) Has it been tripped?

[Gandalf]

Sorry to hear the bad news Tim hope it proves to be a simple fix - ditto what Doug said mine went AWAL en route to Le Man last year and was the good old immobiliser, since replaced and not a hint of a repeat problem.

Good luck let us know how you get on.

[KTiM]

Hummmm, thanks for the suggestions, I hadn't been under the bonnet at all, the car had been running fine, I parked it in the garage about 10 days ago and then this when I tried to get it out again. I have checked all the fuses and they all look to be fine. I know that it's always hard to find where a noise comes from but "my" noise always struck me that it was coming from under the bonnet. I take it that the fuel pump noise would be the pump priming itself, thus only being heard for a couple of seconds?

Colonel, where might I find this fuel cut out black box, just to be sure.

dougc, I'm wondering if it could be my imobiliser (I'm a bit of a luddite when it comes to alarms etc), what was your problem and what sort of imobiliser was it?

Edited by KTiM on Sunday 3rd June 01:34

[KTiM]

Right, I've been out in the garage this morning. Fuel pump fuse checked and is fine, as is the fuel pump relay that I changed with the boot lock relay and both relays worked on the boot. I have also checked the pump itself by giving it a direct 12v feed and it which made it "wherrrr" in both directions - I'm still not sure that that is "my" noise.

[Danny Hoffman]

CD changer?

[KTiM]

Nope, no CD changer fitted.

I have, this afternoon, managed to get the car to start by running the fuel pump off a spare 12v battery, with leads going directly to the pump. So, with the fuel pump fuse and relay checked I'm no thinking that it's an alarm/immobiliser problem. Anyone have any experience with a Laserline 996v3?

[redwedge5]

Its probably a long shot and you may have already tried it, but when I had an electrical problem the fuse looked OK (even to the AA breakdown technician), but it was only when a brand new fuse was tried that everything started working again.

[KTiM]

Thanks but I tried a fuse that I knew to be working just to be on the safe side.

Thanks for the suggestions, any others are most welcome.

[350zwelgje]

Don't know what the electrical power requirements of the pump are, but if the normal cables are not ok, perhaps it doesn't get enough juice. Seems that many of us, with the age of our cars, get more and more intermittend issues with the cabling itself as well (besides the rest needing our devoted attention).

Rob

[The Colonel]

KTiM said:

Colonel, where might I find this fuel cut out black box, just to be sure.

Its screwed to the side of the pedal box. Size about 50 x 50 x 25mm from memory.
Pull knob up for off and down for on (normal position).

I always hear the priming noise coming from rear offside under the car i.e. the pump.

[Hormone]

Obviously the answer has already been given - fuel pump.
This happened on my 400. Ran superbly with no hint of a problem then next day would'nt start.
On advice I had changed fuses,relays and had half the wiring loom out before I relaied that the reason I was 'getting no power' to the pump was that by the time I had turned on the ignition & got under the car with the meter the relay had shut off the power! It sent me in totally the wrong direction.

Changed the pump & away she went.
It would be worth checking the rubber bushes etc on the mounting when you replace as mine were shot & probably the vibration caused the pump to fail.

Good luck.

Brian

[TVRleigh]

When My pump went, it would work with a direct feed, but but via the car feed, but the new pump worked fine on the car, it seems that duff pumps will work for a while with a direct feed. so don't asume that the pump is ok just because it works on a direct feed. I think the extra current on a direct feed, will force the last bit of life out of the pump.

[KTiM]

Ahhh, good advice there, thanks. Anyone know the part number or what sort of pump I need?

[combine]

Number on pump , take it to your motor factor , easy to get hold of , about £65 inc vat , mine went last year or was it year before ...

[KTiM]

Thanks.

[pwd95]

Have you fiddled with the fuel cut off switch? (little black box with push pull knob) Had exactly the same problem with my old 400SE.