wont start with a jump / push start

[beecee]

I left the lights on last night and drained the battery , so i tried a jump start with 3 adult males pushing and it wouldn't start , started 1st turn of the kay with jump leads , any thoughts ?

[witsend]

Is it that the fuel pump has to run for a while first to get fuel to ignite?

[beecee]

i really have no idea , just any other car would start with a push if it jut had a flat battery .

[steveinjapan]

witsend is right - these aren't the same simple cars we were raised on. There's probably a bit more to it than the fuel pump but whatever, I keep a cheap set of jumper cables in the boot and they have come in handy more than once.

[Steve_M]

It all depends how flat the battery was.

It's never going to start by bump starting if the voltage is so low that the battery can't run the ecu, the fuel pump and the ignition all at the same time. Normally the ecu will have a voltage threshold e.g. 9 to 10 volts which it would shut down. So once the ecu detected engine revolutions it would try to run the fuel pump which would drop the ecu below its threshold and it shutdown.

Any fuel injected car will require similar battery voltage to get the engine running, whereas a carbureted engine only need enough voltage just to keep the ignition energised which has a lot lower threshold and fuel would be supplied by a mechanical pump, so as the engine turns fuel is supplied, and there is likely be enough fuel in the carb float chamber anyway to get the engine started.