Help - Car won't start!

[Martin J]

Those voltages sound low at the fuel pump But as you know when everything was working the moment you deactivated the immobiliser you hear the pump prime for a couple of seconds.

Only an idea but can you hook up a via jump leads a booster battery & see what effect that has on your readings. Lead acid batteries are fickle things & assuming you have the banner battery they can be sensitive to long periods of sitting idle. Did you have it hooked up to conditioner? How are the electrolyte levels?

[charlie_pank]

I think you need to be a bit more methodical with this, for example, we know that the FIA switch works ok because when big red key is removed, s/motor does not turn, but with big red key in, it does. We can also stop worrying about the battery because jump-starting doesn't work either.

 

I'm not sure where you're getting 4 wires on the fuel pump. The test I was suggesting was to take a the +wire out of the inertia switch and brush it on the +terminal of the battery. If this gets the fuel-pump priming then the problem is upstream of the inertia switch, If it doesn't then your problem is downstream of the inertia switch...

 

PS just been to garage and done a little test for you, the inertia switch has 12v across it when the ECU is priming the fuel line.

 

Edited by - charlie_pank on 14 May 2012 21:10:58

[ric355]

I wonder if you have a dodgy fuel pump relay. If it is, it might be what you can hear clicking. See if you can swap it for a less critical one to test if you don't have a spare. That could also explain a low or no voltage at the fuel pump.

[bigsi55]

Hi,

 

Just tried brushing the inertia switch wire on the battery. The fuel pump primes. Also, the fuel gauge read 50% so I now know a couple more things:

 

Fuel pump is fine

Battery is fine

I have enough fuel in the tank

 

Soooo, the problem appears to be in the wiring between inertia switch and battery.

 

I also checked:

 

Relays, these are all fine. I swapped them all into the light and indicator positions, and they all work fine.

Fuses are also all fine. Swapped these out to check in the same way.

 

The wire from the inertia switch goes to the starter relay. The other side of the relay goes to:

 

Ignition switch

Starter solenoid earth

Engine harness

 

Earth looks ok, engine harness I have no idea about. Would the ignition switch indicate an immobiliser problem, or any ideas where to go from here?

 

Thanks,

 

Simon

[Bio]

The fuel pump gets it's voltage through the contacts of the fuel pump relay. The relay coil is switched by the immobiliser.

Does the relay coil operate to close the contacts?

Trace the wires that go to the contacts and connect them or bridge them, if the pump runs the fault must be with the relay.

 

John

[charlie_pank]

Ok, so the next thing to check is the relay and the wiring to it. You need to figure out which of the leads to it is the +feed from the ECU (via the 'engine harness' you mention. Disconnect that lead from the relay, then use a spare bit of wire to connect it to the + of the battery while the ignition is on. The fuel pump should prime, if not, the relay or its wiring is bust.

[bigsi55]

Hi all,

 

For any of you that had your money on the ECU being knackered, you win a prize! Took the ECU to Caterham Midlands today, and it basically is funked. Not great for a 15 month old car, but hey ho.

 

Apparently this is only the second sigma ECU that has gone that they know of. I feel like I'm in a special club!

 

Seriously though, I really appreciate all the help with the troubleshooting, makes me glad I joined the club

[Martin J]

Was it replaced free? They are expensive aren't they 😔