Chimaera 4.0 ‘96 Fuel pump wont prime.

[cheltgar]

Trying to get to the bottom of why my Chimaera won’t start…. And know this may be a similar line to lots of other posts on the forum.

Basic description that everyone knows. Disarm alarm, and put ignition into activate, but not start – Don’t hear the fuel pumps priming.

Assumed first thing to try – ECU and Fuel Pump relays in passenger footwell. They are both ‘clicking’ in. Have removed the relays and bench tested them both, and they appear to be fine.
Have added a bulb to the output of Fuel Relay, and it lights for 3 second on ignition – so assume 12v out of relays (Pin 87). Cable out of relay for me is White / Purple.


Disconnected the inertia switch, and applied +12v to the output, and the fuel pump runs. So I assume from inertia switch to fuel pump ok.
Have bridged the inertia switch, and turned on ignition, and fuel pump doesn’t prime (also tested for continuity across inertia switch and OK) so I assume its not the inertia switch. Output from Inertia switch yellow wire – input into inertia switch yellow / black wire.

In the first instance – have I missed anything obvious?

Secondly, how and where are the terminations between the white and purple wires out of the Fuel Pump Relay, (located in the passenger footwell) until it turns into the Yellow / Black wire that are the input into the inertia switch located under the passenger side dash?
I can see a black plug / socket I the footwell with linking wires, but all appear to be back - so even if this is in circuit, they must also connect in at least one other place.

Looking at the schematic on page 270 of the bible, there appears to be a block F:G coming back from the Yellow / Black input into the inertia switch. Any ideas what this is? What colour? Where in the car?

Any help greatly accepted

thanks

[cheltgar]

Hi

N7GTX - Thanks for the info re the wires behind passenger B Pilar. Didn't know they were there.
However, I cant see either a white with purple wire (output from the Fuel Relay) or Yellow Black (input to the inertia switch).

I have just made a bridge directly out of the fuel relay into the output of the inertia switch, and that primes the pump as expected (both signifying the connections to the pump and earth from the pump ok, and also that the fault lies somewhere between the two). BUT WHERE.....

Penelope Pitstop, I had seen that diagram, but still cant find either a black connector with the white / purple wire going in, or a brown connected block anywhere on my car.

Belle427 Could be through the immobiliser, but the diagrams I have managed to find on line don't show this? Not sure how I could find out, as cant find where the white / purple wire goes

[cheltgar]

Am guessing fuse between battery and supply to fuel relay, but don’t know.. could be between fuel relay and inertia switch. Anyone know ?

[cheltgar]

Thanks Steve and chimpongas
I have tried hard reset by disconnecting battery

If I have a dodgy immobiliser, understand how to bypass this circuit now, will try tomorrow, but are there any other circuits I should also bypass?

Thanks in advance

[cheltgar]

Thanks Steve and chimpongas
I have tried hard reset by disconnecting battery

If I have a dodgy immobiliser, understand how to bypass this circuit now, will try tomorrow, but are there any other circuits I should also bypass?

Thanks in advance

[cheltgar]

Hi Chimpongas

Thanks for the Immobiliser bypass instructions.

Took top off dash, to gain access to alarm, and test the output of the two power leads from the black socket, and wasn't getting 12v. So checked all fuses. All fine. Then before re-testing tried disarming the immobiliser with the fob.... and the fuel pump kicked into life, for the first time in few weeks of trying! Clearly an intermittent problem, as hadn't got around to making the modification (which I will probably still do).
However, now when turn the key to start... nothing.

Could this also be an immobiliser issue, or is there something else I could look at before making the modification. Really not keen to make the mod if there is another issue and worried about changing too many things at once now the fuel pump is priming.

Thanks

Gareth

[cheltgar]

Not sure I proved the immobiliser wasn't switching, as I didn't actually do the bypass, couldn't see 12v at the appropriate wires, so went to check fuses etc before making the modification - and it came to life. (I did spray contact cleaner onto the black connector in the footwell, not sure if that took time to take effect or not - could be unrelated).

I had sort of got my head around the fuel pump circuit - linked relays etc. but don't really know which connectors to test for the starter circuit out of the back of the alarm to the immobiliser.

Chimps explanation was super helpful anyway!

[cheltgar]

Hi ChimpOnGas

Do you mean just the two thick wires - do they control both the ECU and starter solenoids to the immobiliser, or will I need to do the total bypass?
I am getting the fuel pump now priming, but nothing when I turn the ignition to the starting position.

Sorry for double checking, but want to be sure doing the correct thing before splicing into the wiring loom

thanks in advance

Gareth

[cheltgar]

Thanks everyone for your help (especially ChimpOnGas). Just done the partial immobiliser bypass - and the TVR has sprung back into life!!! Perfect for this boiling weather we are having.

I know, being a TVR, doesn't mean it will start in the morning, but at least wont be the immobiliser thats killing it.

Probably due for a speeding ticket now after it not running for so long

Gareth

[cheltgar]

Am guessing fuse between battery and supply to fuel relay, but don’t know.. could be between fuel relay and inertia switch. Anyone know ?