Electrics flickered, engine backfired, no start

[Quinnyfreefly]

Hi All,
91 Jetta 1.8 Automatic. Driving along highway and fuel guage suddenly dropped to empty, lights flickered and then engine backfired twice(very loud), pulled over and engine shut off. Tried turning the key and engine wouldnt turn. Battery light usualy comes on when you turn the key but now it doesnt. All other lights are working. Waited an hour went and turned the key and it turned over for 1 second and then stopped and a loud humm could be heard(much louder than fuel pump) Looked at my timing belt and cant see any missing teeth or anything. Electrical short maybe but honestly am stumped!
Any thoughts would be appreciated.
Quinny

[denisond3]

The fuel gauge dropping to empty would indicate the main ignition circuit or the accessory circuit had gone down. This could be from a bad relay, or a connector pulled loose from the back of the fuse and relay block - or some other breakdown of the wiring. Have a close look under the hood at where the wires emerge from the cowling and run into the engine compartment. My Jetta had a leak from the EGR at that point, which melted the insulation on some of the wires, which then shorted together. **
Also, if you had a battery connection go bad, the car wont run just because the alternator is being turned by the engine, because (unlike generators) the alternator must have some voltage on its field coil (the inside part that spins) or it wont generate any output voltage at all. So look for a weak or corroded battery terminal, and check the length of the ground cable, all the way from the battery to where the ground cables (there are a couple of them) connect to the engine or transmission or the body of the car.
Its rare for a battery to utterly fail, but it can happen, from a cracked connector internally, between the 6 cells. This can also be intermittent - and come and go; which makes finding it about impossible. Though putting in another battery would eliminate that as the problem.
I always take a penknife and gently scrape the battery posts, and the internal diameter of the battery cable terminals. This ensures a clean connection.
If your Jetta has the same type of connectors as mine did, made of thin steel pieces - I consider them to be feeble. When one gave me trouble, I replaced it by soldering on one of the battery terminals that bolts on. The kind made of brass can be soldered. The kind made of lead will just melt if you try to solder them.
** I always install an underhood light when I get a car. But if the problem is with the battery connections itself - that light goes out. So...Its handy to carry a flashlight small enough to be held in your teeth, if you need to work on your car in darkness at the roadside.

And could the loud hum have been the heater fan? Or the radio now tuned to some default frequency like 87.5?

[Quinnyfreefly]

Hi Denisond3, thanks for your post. I will check the relays, and I think that the battery is cheap and old so I will take it out and try a new one. I think your right about it being an electrical thing but the backfiring scares me. I will let you know later how it goes. Thanks again its much appreciated
Quinny

[Quinnyfreefly]

Well sorry for the delay. I charged the battery over night and it held a charge perfectly the next day. Then moved on to the alternator. Took it off and the bearing was shot as the pulley could wiggle back and forth.
Replaced alternator and everything has been perfect since.
Cheers for your input denisond3 its very much appreciated

[denisond3]

Much Thanks for the feedback! Happy it got fixed.