push starting on flat battery ( mgb sorry )

[jms700]

had a flat today because i left the lights on :( (pretty daft)

the car wouldnt push start ( even on a big hill) and iv been told you cant push start mgb's on flat battery because of the electric fuel pump, is this true? if so is there away to prime it ?

thanks

[heraldcoupe]

The float chambers should hold plenty of fuel to get the car started, and to run it for a hundred yards or so.
If the battery is totally discharged, you won't have enough energy to fire the ignition, which seems far more likely. This is particularly true if you have electronic ignition,

Cheers,
Bill.

[jms700]

thats what i thought as well, but the mg  has hif's with the float chumbers underneath the carbs so will these hold less fuel than hs's?
if it were hs i would of been able to just fill up the float chambers if i had too which is annoying.

dont have electronic ignition. but the ignition sounds foar more lickly your right.


thanks

[Nick Jones]

Enough fuel in the carbs, even HIFs to fire up.

If the battery is really flat there won't be enough power for a spark, and more importantly not enough to energise the alternator to make more power.  Has to be pretty damn flat though.  Get it on charge quick - just a few hours in that state will ruin it through sulphation.

Cheers

Nick

[jms700]

i wasnt at home, i called the aa and the guy came in 15 minutes started it up with a booster pack, waited 10 minutes while i held the revs up,  ( iv got a bit of a dody alternator) and then he followed me home for 20 minutes. ( and he didnt even note it as a call out :) )

the aa do a great service.

thanks

[TedTaylor]

Some of those 'boring old fart' tricks.

Leaving the car to stand for a while .... making sure all electrical items are turned off  ;) .... can allow the battery to recover a little energy (its to do with the chemistry of a secondary/rechargeable cell and depends upon how deeply discharged the battery is).  It will not restart the car on the starter motor (which would waste this energy) but there may be enough to energise the coil and to enable the car to be push started.  If only having to worry about re-energising a coil then it often works but when the extra demand of a fuel pump is added then it is less likely.

It is one of those tricks that if you are stuck there is no harm in trying (and yes I have done it).  Once the engine is running the generator (dynamo or alternator) should put out enough energy to get some charge into the battery assuming with an alternator there is enough residual energy to excite it (and no silly jokes please!).

Another get you home trick if you are offered a jump start and because of the way the cars are parked and location of batteries, the jump leads are too short.  If the cars are of the same polarity (positive or negative earth) and both have plated metal bumpers or you are prepared to scrape of paint (unlikely on more modern cars) push the two cars together so that the bumpers firmly touch which will give you an earth contact.  Then with any luck clamping the two short (red and black) jump leads together should enable you to be able to link the feed side of the batteries together and you can 'jump' the car with the dead battery.

Finally with a dynamo equipped car temporarily borrow a battery and get the car running on that, then with someone keeping the revs up remove this battery and replace it with the flat battery when the dynamo will get charge into the battery. DO NOT DO THIS WITH AN ALTERNATOR BECAUSE YOU WILL BU**AR IT UP

Ted

[jms700]

thanks, i will keep that in mind.

the jump leads being to short was the problem i had, and spent abput half an hour in the wind and rain trying to get a set of leads to reach a van ( the batterys i nthe back seat so hard to get too)

once we got the leads on, the leads wouldnt even work. wasnt to happy about that.


thanks

[That Man]

Also! depending on which HIF carbs you have it might have a anti-run-on valve which shuts off the fuel when the ignition is switched off.

Gordon