Electrical issues, High idle, stalls when brake is applied. (Page 1/4)
Zach85GT JAN 08, 01:51 PM
85 GT wouldn't start in the morning, so I boosted it and all was fine for the morning. Then I hit a bump and it cut all power to my car for a split second, Then after when I pressed the brakes I can hear the idle crimple down(almost to a stall), It seemed like an electrical issue so I turned headlights and radio off, and got home safe. The battery was a 2 1/2 year old Ever start, so I went to Walmart and got a replacement under warranty as my first step. Car started and didn't have any issues until the next day, where it wouldn't start on it's own again, boosted it again, then when I pressed the brakes it stalled instantly.

I was thinking it was a bad ground, or alt. I looked for the engine to R/H deck hinge ground and found it was broken off and floating, Got a new ground strap from AZ cleaned both grounds, greased it, then boosted the car again, I was able to press brakes and lights seemed way brighter but then 5 min later the same issue where i press brakes it it stalls, lights dim and It won't start on its own. I've checked most of the common grounds and they all look okay. I thought that the broken ground would fix my issues but now I'm at a loss. Could that bad ground have killed my battery and now that I fixed the ground I need a new bat again ?

I was possibly thinking a bad alt, or fusible link. I've tried to look around the forum and ogre's cave for this symptom but no luck.
any suggestions would help a lot. I'll be back for updates.
(Edit)>also forgot to add that every time I boost it, the idle jumps from about 16-1700 until I add a load on the electrical and it stalls.

Thanks, -Zach

[This message has been edited by Zach85GT (edited 01-08-2023).]

IMSA GT JAN 08, 03:56 PM
Do this CAREFULLY so you don't tangle the cable in the motor. Take a pair of jumper cables and use only one of the cables to tie from the negative of the battery to one of the bolts on the engine. Make sure the rest of the cable is out of the way of moving parts. Start the engine and see if it stalls.
Mike in Sydney JAN 08, 05:00 PM
Poor ground? What does the negative cable from the battery look like?
theogre JAN 08, 05:53 PM
Jumped/Boost battery takes time to charge... If the battery is still good... Starter Batteries are often wrecked drain < ~ 11v and may charge but damage will shorten the lifetime a lot.
If you drive after jumping then needs highway speeds and 30min to 1 hour or more to charge.
Is better and often safer to charge w/ 6-10a plugin charger.

But new battery dies overnight.
can be bad alt, gen 1 HL motor or releys, etc.

Turn on to Raise HL then pull plugs for the motors and leave motors disconnected.
Pull the alt and get part store to check is working etc. SI alts are know to kill a battery when diodes are bad.

See my Cave, Battery & Battery Leaches
Get a small DC Amp Clamp to find problems faster and w/o disconnecting/cutting wires.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 01-08-2023).]

Zach85GT JAN 08, 07:35 PM
I will try to jump the car tomorrow morning with neg to a engine bolt, Any specific bolt that works best/won't work ?

Mike, I was thinking the same with a bad bat ground, but I disconnected the big bat cable and wire brush cleaned the end, greased it and it looked good for the most part.

Ogre, I was trying to leave it running for a bit after boosting it, but after around like 10-13 min it stalled on its own, the RPMs start super high like around 17-1800 don't drop until it starts to go down to around 700 and barley run then stalls. Keep in mind that at any point I press brake or turn on head lights it will kill the car also.

Thanks guys, I have all day tomorrow after 4 to work on it.
Mickey_Moose JAN 09, 02:33 PM
If you battery is going dead overnight to the point you have to boost it - you have a short someplace that is killing the battery.

I would start there.

Get a current meter and measure the amperage coming from the battery while it is parked (key off). Check Ogre's Cave: http://fierocave.shorturl.com/ratio.htm
Zach85GT JAN 09, 04:54 PM
The Current with a multi meter is 11.1 v... it Should be around 12.6v (parked and key off) correct ?... I haven't tested volts while running yet... The volts should be around 14.4v on running fieros correct ?

I like the idea of a short because after I shut the car off the battery is dead instantly...

Getting to work on it now... Thanks.
ArthurPeale JAN 09, 05:01 PM
I'd definitely check your grounds - especially the one that goes to the engine block.

On my 86 SE the nut that holds the terminal tight to the bolt had backed off at some point in the past. The whole thing had rusted. The terminal was just wiggling up and down with my fingers.

How it was able to run as well as it did, I have no idea.

I replaced the bolt and negative wire and was surprised how much better it ran.
Patrick JAN 09, 08:28 PM

quote
Originally posted by Zach85GT:

The Current with a multi meter is 11.1 v...

I like the idea of a short because after I shut the car off the battery is dead instantly...



We go down this road so often here.

If your Fiero is killing its battery while just sitting there, the first thing to check is the headlight motors. Disconnect the single wire that goes to each motor and see if the battery now retains its charge.
sleek fiero JAN 09, 09:03 PM
sorry to break in but when I read this it reminded me of mine one day. I would touch the brakes and it would stall or idle would go up. After some checking I found that the brake booster diaphragm had a hole in it. we put in a fresh booster and everything returned to normal. just an idea to check.