Let down for the first time - 100 yards from home.
Let down for the first time - 100 yards from home.
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Macbags

Original Poster:

119 posts

72 months

Friday 3rd June 2022
quotequote all
After four years of faultless fun my 450 let me down for the first time, ran perfectly for half a hour and then suddenly stopped running 100 yards from home. Very kind neighbours helped push her home and she’s back in the garage albeit I had to endure a bit of micky taking.

Sooo….

Half a tank of fresh fuel.
Alarm appears to de activate
Still turns over fine and plenty of juice in the battery
Absolutely nothing.

Left her for an hour to cool down and xactly the same as the above.

So where to start?

My first thought is fuel pump as I don’t have that customary whirr after de activating the alarm. Do I just check for voltage between the pump terminals or should I be checking fuses first….if so where are they?

Any other thoughts and suggestions?

Charlie

s p a c e m a n

11,372 posts

165 months

Friday 3rd June 2022
quotequote all
In the battery area in the passenger footwell is a relay on a blue plug, the fuel pump relay. You should be able to feel it click when the fuel pump should be priming, ie when you first turn the ignition on. I'd start there.


sixor8

7,085 posts

285 months

Friday 3rd June 2022
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If it's still on the original alarm / immobiliser system, this could be at fault. The commonest fault is failure to even turn over (starter solenoid circuit) but the immobiliser also disables the fuel pump / ECU.

You say the pump doesn't run but the car will crank so as above, it could also be one of the relays.

s p a c e m a n

11,372 posts

165 months

Friday 3rd June 2022
quotequote all
Yeah if it's not clicking you need to check if it's getting signal power, if it's not getting any signal then check that the ECU relay next to it operating when the ignition is on. If it's not it's probably immobiliser.

Just a thought. Above the passengers knee is an access hatch into the bottom of the dash where the fuel pump inertia switch is, check the button hasn't popped out.

Your fuse box may differ depending on what day of the week they glued your car together hehe


Tyre Smoke

23,018 posts

278 months

Friday 3rd June 2022
quotequote all
Also, you may find it will bump start ok. This happened to me on the way home from purchase. The wires had become corroded and disintegrated due to lack of use. No fuel pump whirr, but bump started fine.

It'll be something on that pile of loom and relays sitting on top of the battery.

Macbags

Original Poster:

119 posts

72 months

Friday 3rd June 2022
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Thanks guys I’ll have a look tomorrow, fingers crossed it’s just a bad connection somewhere?

x 7usc

1,431 posts

212 months

Friday 3rd June 2022
quotequote all
you didn't hit a pot hole or bump in the road did you, it could have set off the inertia switch for the fuel pump

QBee

21,806 posts

161 months

Saturday 4th June 2022
quotequote all
As said above, the symptoms are exactly what I had when my roll over cut off had popped.

Finally, do try locking and unlocking the car to reset the immobiliser.

Edited by QBee on Saturday 4th June 09:57

Macbags

Original Poster:

119 posts

72 months

Saturday 4th June 2022
quotequote all
Hi

Fuses are good
I can feel a very faint click from the relay when disengage the imobiliser
I think I’ve found the fuel cut off / inertia switch ( see photo) but don’t know how to reset it? It has a rubber diaphragm thing one end which I’ve pressed and prodded but couldn’t feel any switching?
If all the above ok then I’ll roll it out of the garage, jack it up and check if I have power to the fuel pump…..maybe tomorrow if the weather holds off and I’m not dragged round the neighbours to eat cake and drink pins!!!

Any other suggestions?

C

Edited by Macbags on Saturday 4th June 17:25

Polly Grigora

11,209 posts

126 months

Saturday 4th June 2022
quotequote all
You could check if there is a positive supply at the inertia switch before jacking the car up to test at the pump

If there aint no juice to the inertia switch there won't be any pumpy taking place

Belle427

10,810 posts

250 months

Saturday 4th June 2022
quotequote all
Pressing the rubber reset is all you need to do, you should feel a noticeable click if its tripped and needs a reset.
I'd do as you suggest and see what your missing, a test light is useful and better for this something to load the circuit up with a few amps.

Steve_D

13,799 posts

275 months

Sunday 5th June 2022
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Another favourite loss of power is the connectors in the passenger side 'B' pillar under the carpet flap.

Steve

Macbags

Original Poster:

119 posts

72 months

Sunday 5th June 2022
quotequote all
Thanks for all your help, she’s back up and running. It did end up being the relay and it’s incorrect to test them by simply stopping over the main relay and fuel pump relay as both appear to be needed to be functioning correctly to run? I was lucky and had a couple of spare relays in my box, replaced the fuel relay with a ‘new’ one and the pump started.

Sadly I was one hour in and re tracing steps after having the rear wheel off and checking the voltage at the pump end…good earth but nothing off the positive terminal……retraced all my steps and tried replacing the relay and bingo.

Thanks again for all your support.

C

Steve_D

13,799 posts

275 months

Sunday 5th June 2022
quotequote all
You did fit the correct type of relay?
It is an uncommon configuration having 2 pins marked 87 (ie not 87a or 87b etc).

Most 5 pin relays are a 'change-over' type where pin 30 is connected to 87a when the relay is off and connects 30 to 87 when the relay is activated.
If you fit the wrong type it may well seem to work as the fuel pump now comes on but when you switch everything else off the lambda sensor heaters will be running full time which will take down your battrery in short order.

Steve

Macbags

Original Poster:

119 posts

72 months

Sunday 5th June 2022
quotequote all
Not sure Steve….. the replacement Bosch relay had the same number but was brown plastic rather than the metal of the original?

Polly Grigora

11,209 posts

126 months

Sunday 5th June 2022
quotequote all
Nice fix

Zener

19,222 posts

238 months

Sunday 5th June 2022
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The later correct relay has a brown plastic cover rather than metal , well was the last pair I purchased through Euro Car Parts as it's a 80's injection BMW relay also

Tyre Smoke

23,018 posts

278 months

Sunday 5th June 2022
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Let's face it, if it's the wrong one, you'll have a flat battery in the morning. biggrin

Zener

19,222 posts

238 months

Sunday 5th June 2022
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0 332 014 112 Relay Land Rover BMW Jaguar

s p a c e m a n

11,372 posts

165 months

Monday 6th June 2022
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Yeah you need both as one is for the ECU and the fuel pump won't run without it. I've pulled the cap off of an old dead relay and squeezed the contacts together, good as a tester or a get you home bodge. Change both for new ones, if one has died the other has probably had as much usage.