Car question for mechanics

[awagnon]

I guess you can't bump start or push start a fuel injected BMW motorcycle if the battery is nearly completely dead because there must be some juice to pressurize the fuel injection system. Does this also apply to cars? I have a Honda CRV with standard transmission. If the battery was dead, would I be able to push start it with it's fuel injection system?

[adamceckhardt]

I guess you can't bump start or push start a fuel injected BMW motorcycle if the battery is nearly completely dead because there must be some juice to pressurize the fuel injection system. Does this also apply to cars? I have a Honda CRV with standard transmission. If the battery was dead, would I be able to push start it with it's fuel injection system?

I am not a car mechanic, but I am a mechanic, and I used to work at a Honda dealership, and I once stayed at a Holiday Inn Express.

With that, I have successfully bump started a CR-V with a dead battery. How dead was it? Dead enough that the engine wouldn't crank. Give it a whirl. If you're not feeling adventurous, just call a tow truck.

[awagnon]

I am not a car mechanic, but I am a mechanic, and I used to work at a Honda dealership, and I once stayed at a Holiday Inn Express.

With that, I have successfully bump started a CR-V with a dead battery. How dead was it? Dead enough that the engine wouldn't crank. Give it a whirl. If you're not feeling adventurous, just call a tow truck.


Thanks, Adam. That was a fast response. I'm sure if I would try it before calling a tow truck. One of the reasons I like standard shift, is the ability to bump start a car if needed. It just never occurred to me before that it might not work with fuel injection.

[BuddingGeezer]

A car battery could be dead but it would have to have enough power to run the fuel pump or either the alternator would need to turn fast enough to supply enough power to run the fuel pump. Unlike a carburetor which has fuel in the fuel bowl if the fuel pump doesn't send fuel to the injectors the engine won't start.

Ralph Sims

[BubbaZanetti]

cut the wire to the pump and tape a 9v and two AAs in series near the pump :)

[dsenn]

battery cannot be totally dead if you want to bump start any vehicle with an alternator and injection. There is no residual magnetism in an alternator like there is in a generator so the battery has to have enough life left in it to energize the field in the alternator, once that is done and the engine turns fast enough for the alternator to produce current it will produce enough to operate the injection system and charge the battery. The old cars with a generator were capable of bump starting with the battery removed because of the residual magnetism all it needed was enough RPM. An alternator requires some voltage initially to produce more.
(over 45 years auto/heavy truck mech.)

[PGlaves]

In addition to having enough power to run the pump the battery voltage needs to be/stay high enough to be above the low voltage limit for the brain - ECU. Somewhere around 10 volts, probably

[lkchris]

battery cannot be totally dead if you want to bump start any vehicle with an alternator and injection.

Or any engine with spark plugs, for that matter. Save maybe those with magnetos.

[john1691]

Ummmm, just going out on a limb here, but.........did you try jumper cables?

[108625]

Keep in mind that a "dead" battery is one indicating less than about 11.7 volts.
It may not have enough of a charge to do anything noticeable when you turn the key, but can still power the fuel pump and ignition if you can just get the thing turning over.
When I was a poor airman stationed in Germany, could start my "dead" '81 GTI because I lived on a hill. Turn the ignition to run, put it in second gear, release the brake and dump the clutch halfway down the hill. It fired right up every time.
I milked that battery for about a week before I had time (or funds?) to replace it.

[crazydrummerdude]

Or any engine with spark plugs, for that matter. Save maybe those with magnetos.

I disagree, from experience.

But, I wonder if my truck could be bump-started. That would be cool.

[osbornk]

Or any engine with spark plugs, for that matter. Save maybe those with magnetos.

You can push start a vehicle with a generator, conventional ignition and a carb. (and the battery doesn't matter). Been there and done that manyand many years ago working at a used car lot.