URGENT No power to fuel pump, fuse and relay ok

[DuncanM]

Hello,

We are trying to fire up the Cerb after years off the road.

It is cranking over nicely but we're not getting any power at the fuel pump.

We have checked the relay and both switches are working fine. The fuse is fine too.

The immobiliser is switching off ok.

If anyone can help it'd be much appreciated!

Regards

Duncan

[sonnylad]

Have you tried tapping the casing of the fuel pump as they can stick, a sharp shock may do the trick.

[DuncanM]

Hi,

We've checked the pump with a spare battery and it works fine. Are problem seems to be that when pressing the start button we're getting no power to the fuel pump.

Relay and fuse have both been checked.

Duncan

[Ireland]

Try tapping the immobiliser.

It might just be an issue there and tap may sort it (temporarily).

Otherwise get a wiring diagram and check using that.

[M3John]

Not the fuel inertia switch?

[DuncanM]

Hi John,

Can you tell me where the fuel inertia switch is please (and what it looks like).

Duncan

[itiejim]

Top left hand side of the fuel tank (looking from the back) it's just a sort of button that needs to be pressed in IIRC.

[M3John]

DuncanM said:

Hi John,

Can you tell me where the fuel inertia switch is please (and what it looks like).

Duncan

Well mine is mounted in the space above the fuel tank behind the Velcroed on carpet roughly in the center of the car. It's a large switch with a big rubber bung (as the button part) and has one wire/plug into it.
Just like THIS ONE only just mounted with the rubber bit at the top.

[DuncanM]

inertia switch seems ok, stripped it and is making contact both sides. So back in the car, still no power to fuel pump.

So far we've
1. checked fuse in drivers side boot fuse box
2. checked relay in drivers side boot fuse box
3. checked 'big fuse'
4. Starter works fine
5. Imobiliser light seems to go off ok!
6. The silver key has been bypassed so cannot be this.

How can we check the immobiliser for faults? We've tapped it :-), but still no joy!
And really thought we were going to hear the engine fire up into life this evening :-(

[JensenA]

I've just had a very similar problem that only happens when a car has been off the road for 1 year +. I'm not positive, but I think the Immobilser has separate circuits and the fuel pump could be one of them.
Have you traced the pump wiring back to see if you have a broken or loose connection somewhere?
When you connected your battery did the Alarm go of 'properly' or did it make a feeble weird sort of strangled chirp? If it did, then it points towards a possible immobilser issue.

PS a smiley is just a ':' followed by a ')', ie miss out the '-'

Edited by JensenA on Tuesday 10th August 18:58

[DuncanM]

JensenA said:

I've just had a very similar problem that only happens when a car has been off the road for 1 year +. I'm not positive, but I think the Immobilser has separate circuits and the fuel pump could be one of them.
Have you traced the pump wiring back to see if you have a broken or loose connection somewhere?
When you connected your battery did the Alarm go of 'properly' or did it make a feeble weird sort of strangled chirp? If it did, then it points towards a possible immobilser issue.

PS a smiley is just a ':' followed by a ')', ie miss out the '-'

Edited by JensenA on Tuesday 10th August 18:58

Hi Alan,

We are thinking more and more that it's going to be the immobiliser.

We haven't traced the pump wiring at all yet. Will have to check it next time.

Out of interest, how did you solve your issue?

Duncan .

[Ireland]

DuncanM said:

.....How can we check the immobiliser for faults? .....

You'll need a wiring diagram for the car and a 12v test light.

(As it's what helps to keeps your car from being stolen you'll appreciate us not going into too much detail on-line. )

[JensenA]

DuncanM said:

JensenA said:

I've just had a very similar problem that only happens when a car has been off the road for 1 year +. I'm not positive, but I think the Immobilser has separate circuits and the fuel pump could be one of them.
Have you traced the pump wiring back to see if you have a broken or loose connection somewhere?
When you connected your battery did the Alarm go of 'properly' or did it make a feeble weird sort of strangled chirp? If it did, then it points towards a possible immobilser issue.

PS a smiley is just a ':' followed by a ')', ie miss out the '-'

Edited by JensenA on Tuesday 10th August 18:58

Hi Alan,

We are thinking more and more that it's going to be the immobiliser.

We haven't traced the pump wiring at all yet. Will have to check it next time.

Out of interest, how did you solve your issue?

Duncan .

A new immobiliser was needed

[DuncanM]

Oh dear, Is it time to call Carl Baker?

Arghhh! We are so close. After years off the road the engine is in and cranking over wanting to fire up!

Bloody immobilisers .

Thanks for the replies everyone, I'll post up once it's started .

Duncan

Edited by DuncanM on Wednesday 11th August 11:21

[Ireland]

If it is the immobiliser you'll be able to loop out the faulty circuit and start the car.

You'll still have the protection of the remaining circuits when it's immobilised.

[RUSSELLM]

My fuel pump's been A bit hit & miss of late & I'm fairly confident it'll be the immobiliser. The function to break the circuit on the starter motor failed first, so it makes sense that it will be the same again. Something else to look at. I once left the car facing down hill on the drive for a couple of months & the ECU ended up submerged in water & gave similar symptoms

[DuncanM]

Hello everyone,

Just to let you know that my problem has been fixed now and the engine boomed into life after 3+ years off the road!!!! .

A very satisfying sound I can tell you, like a Spitfire what with no exhaust, just headers .

The electrical problem wasn't the immobiliser in the end.

We called out a local auto electrician and the fault was diagnosed as being resistant rather than a break. It was then traced to a connection at the back of the fuse box.

The immobiliser still works fine .

Duncan

[M3John]

Glad to hear it sir !

[JensenA]

Good news - I'm pleased that I was wrong