Clutch Pedal Start Interlock

[oldmacdonald]

Yeah as a last resort that is what I'd probably do. Might try it on the weekend and see if it works. Just don't want to be doing it for the first time in the bush.

[Yom]

You also need enough voltage for the computer to make all systems go. I suspect the only time a push start will work in a JK is when the starter motor is screwed.

Not enough power and the computer will say no. Doubt it'll even give you any decent warning that its becoming a problem either?

[MightyMouse]

And just as importantly run the EFI pump... all in all not an insubstantial load.

If you caught it as the battery was getting down then pushing would work.

i've roll started mine ( battery ok ) just to see what would happen.... no issues except the fuel gauge suddenly read VERY low. Turned off and restarted - all back to normal. I'll leave that to someone else to explain......

[tdwrangler]

Yep I've heard this before - all cars with electronically controlled fuel systems require a certain level of power in the battery (10 amps maybe if memory serves) for a clutch start to work.

Just out of curiosity though, how much power would the alternator produce as the engine turns over while clutch starting? What I mean is, if you had a long hill and got the car to run down the hill long enough (clutch out, so turning the engine) would that produce enough current from the alternator (even if the battery was dead flat) to give the ECU what it needs to supply fuel?

[Yom]

Originally Posted by tdwrangler

Yep I've heard this before - all cars with electronically controlled fuel systems require a certain level of power in the battery (10 amps maybe if memory serves) for a clutch start to work.

Just out of curiosity though, how much power would the alternator produce as the engine turns over while clutch starting? What I mean is, if you had a long hill and got the car to run down the hill long enough (clutch out, so turning the engine) would that produce enough current from the alternator (even if the battery was dead flat) to give the ECU what it needs to supply fuel?

I remember an auto elec telling me most modern alternators are designed to create their best output ~5000 to 9000rpm. Different sized pulleys mean your alternator is doing a different RPM to your engine - they just act as gearing.

Jump starting would be an unlikely way to get the alternator to generate enough power to run the electronics in a modern vehicle. Also, I don't know about the petrols but I am fairly certain the CRD has a clutched alternator pulley (CBF going downstairs to have a look sorry ) so it is not likely to be spinning at low idles such as a push start.

[oldmacdonald]

One of the reasons I ask is that I have jump started mine once before when (I assume) the battery was only a little bit too low to start it. Got me wondering what I would do if there wasn't a car around to jump start off.

[oldmacdonald]

Originally Posted by Yom

You also need enough voltage for the computer to make all systems go. I suspect the only time a push start will work in a JK is when the starter motor is screwed.

Not enough power and the computer will say no. Doubt it'll even give you any decent warning that its becoming a problem either?

F**kin computers.