Engine dies after 5 seconds

[Boatbuoy]

Hello All,

I'm desperately trying to re-commission my car after its chassis refurb.

I had the engine running for about 3 or 4 minutes on Saturday evening. Everything seemed fine up until the point where the hot exhaust manifold burnt through the battery/starter cable (my bad cable routing!!). At this point the battery was temporarily shorted, but only for a few seconds. Since then I've replaced the burnt cable which meant removing the exhaust and undoing the starter. It's all gone back together but now the engine will only run for about 5 seconds before dying. We think it's a fuel pressure issue, the current sequence of events is:

The fuel pump primes, the engine runs, the engine dies and then the pump automatically runs again.

The battery has been tested and is fine, there's no fuel leaks, and there's fuel in the tank.

Any suggestions as to what's going on?

Best Regards,
Olly

[FarmyardPants]

Sounds like the fuel pump is only running when ignition is on and engine isn't running, which is why it dies and you hear it reprime after it cuts out. It might be immobiliser-related. Good luck!

[Byker28i]

What happens if you power the fuel pump directly?

The fuel pump is fed through the immobiliser circuit, as is the starter. When you get the fault, is your imobiliser red led still flashing in the center cubby hole (under the stereo).

It might be you've upset the immobiliser? It might need a reset in which case opens all doors, boot and bonnet and disconnet the battery for a while

[fatjon]

Boatbuoy said:

Hello All,



The fuel pump primes, the engine runs, the engine dies and then the pump automatically runs again.

That sounds wrong. It should prime when the ignition transitions from off to on and not run again after what the ECU would see as a stall until the starter is engaged. If it reprimes after the stall then that means the ECU lost power and then power was re-established to it.

The above could be bks on the cerbera and mines not an MBE to test the theory but that is the way most ECUs do it, so that in the event of an accident the fuel pump is stopped when the engine is stopped and will not prime until it's power cycled or fully restart unless it's cranked. I would be checking that the ECU is not losing power intermittently.

[Boatbuoy]

Thanks for the replies, keep them coming!

I should add that for various reasons the immobiliser has been taken out of the loop (in accordance with the suppliers guidance).

We now think that the battery short may have upset the ECU. Does it need plugging into the diagnostics software to be reset?

[FarmyardPants]

Did you replace the battery? It might test ok but still worth doing if it has been shorted out.

Edit: also worth checking all the relays in the boot. If one has fused closed it might cause odd behaviour