Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Pontiac Bonneville 1997 battery

Hi all
I have a pontiac Bonneville 1997. Recently the car was stalling also engine looked unballanced and stall. Battery is draining when car is off although the battery is only 3 months old

Sorry Toni, there are too many possibilities associated with your symptoms.
There might be an intermittent electrical problem causing all your symptoms.
But that is going to take a good independent shop to locate.

1 Like

I am still trying to get past"engine looked unbalanced and stall".

1 Like

Yes, noticed that. That’s why I was thinking intermittent electrical. But with a carbureted engine with primitive pollution controls could be unrelated to the battery drain. Vacuum leaks, fuel delivery, primary wiring? Some joker may have even cross wired some plugs.

1997…I don’t think it had a carburetor. I doubt the pollution control was that primitive too

Yeah I think carbs had been gone for ten years by then. So much for professional advice. Best to take it to a shop to look for a drain on the battery. That’s what shops do.

OP must have edited it, originally listed as a 77
Or my eyesight is failing…

Even without the stall, how does an engine look unbalanced? Three cylinders on one side and two on the other?

For the battery draining problem you need a phantom-current draw test. Anything over 50 mA indicates there may be a problem. For the stalling, possible misfiring, start with checking the diagnostic codes stored in the computer’s memory. Before going down these paths suggest to first clean and tighten the battery connectors, see if that has any effect.

Hi all thank you for sharing your thoughts.
I meant by unballanced engine is that when engin is running idle u feel it is shaking and not running smoothly.
I have changed the spark plugs myself and also the wires. Found 2 of the wires badly damaged and “sparking” all over when engine is on. Thus i got rid of the unbalanced engine run. It was a serious misfiring …
As for the battery drain while car is off, i took it to an electician and he said he didnt find any power drain!
So i guess i will have a 2nd opinion on this one. I doubt that the alternator is somehow messed up…

Sorry it is 1997 lol…
Fuel injection system for sure

Thanks George.
I will show your msg to the electrician as i dont know how will i say it myself lol

The basic alternator/battery test a diy’er can do w/an inexpensive DVM:

Before the first start of the day the battery should measure about 12.6 volts. Immediately after starting the engine, at idle, 13.5-15.5 v. If your measurements are outside of that range , some sort of battery, current drain, or alternator problem. Good for you for diy’er solving the misfire problem.