Tyson0317

I found out recently that my '94 pickup has a curious flaw. I have been having a weird electrical leak somewhere - something has a low draw on my battery to where it will kill a full charge if I dont drive for about 3 days. Its been that way for almost a year and I havent had the willpower to mess with it. When the battery got too low to crank, I can usually just push-start. I live on a hill and it's pretty easy to do. Problem is, there seems to be a too "low to start" condition in that if the battery is completely dead (4V or less), the truck simply wont start. I have rolled it all the way down a pretty long hill in gear and it just does not get going (which is frustrating because then I got to walk up the hill to get a battery or the wife's car).

There is obviously something in the system that required some juice for the system to work - which is really lame and unlike every other stick-shift car that I have owned. Does anyone have any idea why this is happeing and if there is a way to "fix" this? The 'Yota is my " hit the fan, run to the woods" truck and I would like it to be battery-independant...

xjdubber

computers need power to work, if there's not enough juice for the ecu the ignition wont work.

easy way to trace down your leak to ground would be to take a 12v light with wires and hook it up to the battery post and the other wire to the ground cable. start pulling fuses after that when the light stops glowing you have found the circuit with the leak to ground.

Tyson0317

I have a number of other (newer) cars with ECUs and they push-start just fine without juice. My '05 Audi A4 will start without a battery at all; my '99 Mitsubishi will roll-start from the dead as does my '95 F-150. All of them have ECUs. The rotation of the engine gets the alternator rolling, thus giving the ECU power. All of these cars even have electronic ignition (which amazingly the 'Yota is still has a distributor).

I wonder if the alternator has a solenoid that needs to be electrically turned on before the current can flow (which would be stupid indeed)...

milehigheric

Alternators are an electromagnetic device...They need power in order to make power, hence the battery. If the battery is beyond the point of exciting the alternator (when the light on your dash fails to come on) then you can push all you want but the alternator wont make power, ECU wont get power, Ignition wont get power, fuel pump wont get power and suddenly your at the bottom of a hill swearing. I am going to call bull on push starting without a battery in place...Unless I am missing something?

What is in the truck that is not stock? Cb radios, alarms, sound systems, clocks? Check after market appliances for parasite draw first.