Fuel pump continually primes

[CraigAuk]

Hi all,

When I purchased my Chim last month I was told the fuel pump had been upgraded to a 'racing pump'.
Well, ever since I've had it the car runs the fuel pump continuously when the key is in the ACC position, ready to start.
It doesn't do the usual prime then stop like everyone else's car does.
Do you know what controls the priming - is it the ECU?
Any idea how I can stop it running continuously?

Thanks

Craig

[s6otty]

The ECU controls it, via one of the silver relays in the passengers footwell.

Worth checking if it has been done for a reason, I'd say they've just bypassed the relay!

Scott

[blitzracing]

Im with above- highly dangerous if get involved in an accident and the impact trip is not working or by passed (check this) - here let me help you by pouring some petrol on that fire!

[CraigAuk]

What's the easiest way to tell? Pull the relay out and see if the pump still runs??

[Simon says]

blitzracing said:

Im with above- highly dangerous if get involved in an accident and the impact trip is not working or by passed (check this) - here let me help you by pouring some petrol on that fire!

+1 Very dangerous the pump can move fuel at an alarming rate

[s6otty]

You can pull the relay, depends on how they have bypassed it, but it does need looking in to, ASAP.

Let me know if you need any info while mine is in bits!

Scott

[MADMAX2]

If it's the fuel pump relays they have bypassed make sure you get OEM original Bosch ones the spurious ones are rubbish

[rev-erend]

There is a sensor at the front of the fuel rail - check its still connected.

[Simon says]

rev-erend said:

There is a sensor at the front of the fuel rail - check its still connected.

That sensor is for fuel temp calculations for the ECU nothing more

[rev-erend]

Ah, fair enough..

[Simon says]

rev-erend said:

Ah, fair enough..

[finestjammy]

MADMAX2 said:

If it's the fuel pump relays they have bypassed make sure you get OEM original Bosch ones the spurious ones are rubbish

Just as an additional note, you can't get the silver/aluminium Bosch relays now. They are brown plastic I thought I'd been sent the wrong ones but it seems Bosch have switched to plastic.

[CraigAuk]

OK - I've had an eyeball at the relays today and I have 2 silver relays, both with 'LUCAS' stickers on the top. They look ancient, so I assume they are 16 years old!

However, none of the wiring looks bodged/bypassed based on my once over - so question 1 is would the fuel pump relay be likely to fail closed? (I would expect a relay, unless it's latched, to fail open)

Second question: there are a couple of 'relay style' connector blocks (multiple spade connectors terminating in a plastic block) - yellow coloured, with no relays attached - is this normal?

[peaktorque]

CraigAuk said:

OK - I've had an eyeball at the relays today and I have 2 silver relays, both with 'LUCAS' stickers on the top. They look ancient, so I assume they are 16 years old!

However, none of the wiring looks bodged/bypassed based on my once over - so question 1 is would the fuel pump relay be likely to fail closed? (I would expect a relay, unless it's latched, to fail open)

Second question: there are a couple of 'relay style' connector blocks (multiple spade connectors terminating in a plastic block) - yellow coloured, with no relays attached - is this normal?

Yes, the relays can fail in the closed position. Have you tried pulling them and seeing if the pump stops?

There are spare connectors attached to the rats nest, just ignore them

[FlipFlopGriff]

Swap the 2 silver relays to see if that works - one is fuel pump, oneis ECU but can't recall which is which.
If that works you've found the problem. Always best to have a couple of spare relays for these 2 as the fuel pump one is a common failure issue. About £15-£20 each the last time I bought some.
FFG