Mr2 Starting Trouble

[Utah]

I am not sure if I can post a car problem here. If not, please feel free to delete. However, I am hoping there is a gearhead or 2 who may be able to help me.

I have a 91 MR2 Turbo and it has been awesome for me. However, it has decided not to start for me periodically and I have no idea what the problem is.

I bought a new battery today and it immediately started. I turned it off and went inside for 30 minutes. I went to go to the bar to watch the Twins with my friends and the damn thing would not start. It just clicked and appeared the battery was dead. I jumped it and went to the game (30 minute drive). It died at the bar and I jumped it again.

I got home and tested the alternator by disconnecting the battery. It still ran so it wasnt that. I turned off the car and tried to start it 4 times. It started immediately every time.

I am clueless and I cant really trust it to drive anywhere. Any ideas would be greatly appreciated.

[d10]

Looks like something is draining your battery while the car is not running. It probably won't be easy to figure out where the problem is. If you need the car for transportation, you could unplug the battery whenever the car is not running and it will probably be good when you want to start it again. I'd also check out www.mr2oc.com if you're not over there already, it's a really good board, they know MR2s there like we know poker here.

[Osprey]

It sounds like the starter is starting to go bad... they get intermittent sometimes before they go for good.The part that doesn't fit is that jump starting is working... Sounds like there's an drain somewhere, an open circuit or something. Any new radios, electronics etc.. recently?

[CORed]

I agree with people that say something is draining your battery. If it is draining in thirty minutes, you've probably got something pretty badly shorted to ground. Even leaving your headlights on won't drain a good battery that quickly. Disconnecting your battery when the car isn't running might be a temporary workaround, but you need to find the problem and fix it (or pay someone to do it). There is enough current flowing that an electrical fire is a distinct possibility. Also, disconnecting the battery while the engine is running is not really a good idea. The alternator, etc. is designed to work with a battery in the circuit, and disconnecting it can cause voltage spikes that could fry electronics. The correct way to test an alternator is with a voltmeter. With a fully charged battery, you should read about 14 volts across the battery terminals with the engine running, and 12 - 12.5 with the engine off.

[CORed]

[ QUOTE ]
It sounds like the starter is starting to go bad... they get intermittent sometimes before they go for good.The part that doesn't fit is that jump starting is working... Sounds like there's an drain somewhere, an open circuit or something. Any new radios, electronics etc.. recently?

[/ QUOTE ]

It could be a starter winding shorting to ground. Or it could be something else shorting to ground.

Edit: On second thought it's probably not a shorted starter winding, becuase that shouldn't be getting any current when the starter is not actually engaged. I still think it's likely somewhere in the starter circuit, because anything else drawing enough current to drain the battery in 30 minutes would probably blow a fuse, the fusible link or burned out a wire. The starter circuit is designed to take heavy current loads. It would be a good place to start when trying to find the problem anyway.

[Utah]

Thanks everyone for the info. I am pretty confused as it has worked perfectly since I made this post - although it could simply be in remission. Is it possible that the connection was not solid on the post and that when I tested by removing the connection when the car was on and then reattached that I got a much more solid connection (note: I cleaned the post a bit when I did the test, although they didnt look bad). It doesnt seem to fit the symptons. However, it is the only thing that changed between working and not working.

[Ricky_Bobby]

When it clicked did the dash lights go out and come back on after you let off the key? The starter takes a ton of power and if your battery connection was bad it typically doesn't have any effect until you try to start it. Usually the solenoid will click and your dash lights will go out from the drain. When you let off the key they come back on. It sounds like this could be your problem. Its not the alternator if it runs without the battery. If there was a drain that could make it go dead in 30 minutes you would've got some serious spark jumping when you hooked your cables up. Kind of confusing that it works with the jump except that the jumper cables are maybe bypassing the battery connection? Maybe the extra pressure assisting the connection. Since it hasn't screwed up since you reconnected the battery maybe you got lucky and fixed the connection. It sounds like either the connection was the problem or the starter/solenoid. Could possiblly be some corrosion with the ground wire or the starter wire where it connects to the starter itself. This is either a really simple corrosion problem or a starter problem. GL

[relsieh]

i used to have a 91 mr2 as well, its most likely the alternator, the mr2 is notorious for having a bad one, i had to replace my alternator twice. Its not the starter if its making that clicking sound nor is it the battery. So get the alternator looked at.

[CORed]

Good point that anything causing a severe drain should cause an arc when battery is connected or disconnected. Something else to consider: Brand new batteries don't always have a full charge when you buy them. There's usually enough charge to start the car, but sometimes you need to run the engine for awhile to get the battery fully charged.

If the problem recurrs, here are some things to check:
Connections: The starting cirucit is a low voltage, high current circuit. This means that the resistance in connections, wiring and solenoid needs to be very low, or there will be a voltage drop which prevents the starter from getting enough voltage to crank the engine. You should check not only the battery terminal, which are the most common cause of problems, but the connection between the cable and the starter, and if the solenoid is a separate unit (as on some Fords), the connections on both ends of the solenoid to starter cable. The solenoid itself can cause problems, because the contacts can burn. Also check the connection between the ground cable (connected to the negative battery terminal) and the engine block. Take the connections aprt and use emery cloth or fine sndpaper to get any metal survaces clean, bright and shiny. Also, lose starter mounting bolts can cause a faulty ground connection.

Cables: Sometimes acid gets inside the insulation and causes internal corrosion on cables, usually on the positive side of the battery. This may not be visible. Calbes are farely cheap. Make sure any replacement cables are the same guage or larger than the originals.

[Utah]

Thanks everyone for the advice. I really appreciate it. It has worked perfectly since. I even had it sit for a couple of days and it started immediately.