Hi all, it's been awhile since I visited here, the job's kept me on the road a good portion of the year, and has kept me buried when I've been in town. Anyway, I have a little problem I'm hoping to get some help troubleshooting. Last week I took the green machine ('91 Formula L98) out for a run. It had been sitting for about 2 weeks prior in the garage I rent over on the mainland. It fired right up, and I cruised out to a low traffic road out west of town to get a few acceleration runs in. I did 3 or 4 runs and the car was running great. On the next run it seemed like the tranny was shifting slow. I got on it once more from a stop and the tranny short shifted, and the car seemed to be running slower. Started heading back toward town at that time. The next run I made the engine cut out or backfired twice. I came up to a traffic light, and I noticed the a/c blower was hardly putting out any air. Next the “Inflatable Restraint” light started blinking. I looked at the voltage gauge and it was down around 10 volts. I turned off the a/c and the radio, and when I left the light the engine was bogging badly…it felt like the timing had changed. I got back to my garage, and when I went to put up the power windows, they would not go up. I revved the engine one more time and it started popping. At that point I shut off the engine, went to restart and there was nothing, not even a click. The battery was dead. Now at this point I’m thinking I lost an alternator, but can’t figure out why all the other stuff was happening. It was getting late, so I closed the garage door and headed home. So today, I load up my jump starter, voltmeter and tools, and head to the garage. I’m fully expecting the battery to be dead. When I get to the garage, I figure what the heck, let’s try to start the car. It started cranking, you could tell the battery was low, but it fired up. I let it run for a few minutes to warm up, then revved the engine. It revved fine, no hesitation, no backfires, no popping. I looked at the voltmeter, and it was at a little less than 12 volts, and dropping slowly. I let in run till the voltage got down to around 10-11 volts, now the car is starting to run rough again, and the “Inflatable Restraint” light starts blinking again. I rev the engine and it’s popping again now. I shut it down, and try to restart…nothing…it’s completely dead again. So I pull the battery (a 4-year old Die-Hard), and take it down to Sears to get it checked. The dude puts it on his analyzer and tells me it’s too dead to test, so they throw it on the charger for 2 hours. They check it again and tell me it’s good. I take it back and put it in the car, it fires right up and runs great, no bogging, no popping, no lights, and the voltage is a little higher than 12 volts. Well, the temp in my little garage today was about 125 this afternoon, so I called it a day after that. Next weekend I’ll check the alternator output. Now my question, can low voltage cause all that other stuff to happen? The only thing I can figure is that the computer starts getting flaky at low voltage and screws with everything else. Has anyone else ever heard of anything similar happening due to a low voltage condition, and should I be looking at anything else? Any help will be greatly appreciated.

 

yeah, low voltage can cause those problems, especially if it's fuel injected and the fuel pump can't maintain adequate pressure.

 

yeah, low voltage can cause those problems, especially if it's fuel injected and the fuel pump can't maintain adequate pressure.

 

Dollars-to-donuts it's the alternator. You're SRS system requires 12V constantly, when it does not get it, the light will come on, or flash, letting you know that the SRS system will not function (as a safety precaution).
Your car was more than likely running solely off the battery. That is most likely why the windows would not roll up.
A discharged battery can sometimes regain some of it's charge just from sitting a while (seen it many times).
Still a good idea to replace the battery when you replace the alternator. They have a tendancy to discharge one or more of the cells. May not even cause much of a problem now, but chances are it will in the near future.

 

Well, start the eng. and using a DC voltmeter jump across the batt terminals paying attention to polairty. If your alt. and voltage regulator are ok you should read between 14.5v and 15.0v on your DC voltmeter.

Auggie

 

I took a voltage measurement today right after I started the car, it was shade over 12 volts. The voltmeter in the car was reading the same. It went down from there, so it sure is pointing to the alternator. It's hard to say when the alternator failed though. I had the car out two weeks before and drove it for a couple hours, and since it was all daylight highway driving, and I typically don't run the a/c when I'm cruising on the highway, the drain on the battery would have been minimal. The alternator really could have died awhile back and I wouldn't have known it. It was just kinda bizarre how a whole bunch of seemingly unrelated anomalies started occuring in a relatively short span of time. It was a good thing I wasn't cruisin' one my way to one of the big events when it decided to go south though...I can just see it failing on me in some tiny little town on a Saturday night...

...been there, done that, got the t-shirt.

Thanx for your responses guys

 

AAAACCCKKK! Paragraphs...please!
Sorry, too hard to read it all as one big mass.

 

It's not so much the fuel pump as the ecm. That requires clean 12 volts otherwise all sots of wierd things happen.
I would also check the ground at the block and the connections at the starter. High moister has been known to do some funky things to those connections. Problems at either will easily contribute to a fried alt.