Car won't start, humming noise at the back of car

Question

I have a 1995 Buick Regal Custom. When I start the car, it spins but doesn't turn over. Electronics work fine and I got the battery tested and both the battery and alternator are completely fine.

When I turn the key back, I notice a buzzing electronic sound coming from the back of the car. It's a lot like a spinning sound and it is not coming from the engine.

This usually only happens if we don't plug the car in on a cold day. But it's not cold at all and even after being plugged in, it still won't start. ​​​​​​​It's probably not the starter since I hear a buzzing sound coming from around the back wheel area instead of ticking sound in the front.

I have expended my only knowledge about cars from my time in automotive class. What do you think it could be?

Answer 1

Ok, so to draw a little bit of a picture with words, the start cycle is basically:

1. Pump fuel
2. Rotate motor
3. Intake fuel/air mixture
4. Ignite

Note that the above is not necessarily in that order and there are some nuances left out.

However, of the components involved in the ignition cycle, most are in the engine bay (engine, starter, ignition system etc). The only component involved in engine starting at all that is located near the rear, is the fuel pump. So this could be the culprit, however it is most likely not the source of the whirring/humming noise. The fuel pump will only operate when the ignition is in the "on" and in some cases "acc" positions, but almost never in the "off" and certainly not the key out position.

There are a couple other possibilities that could create a sound like that which have nothing to do with you engine issue. The 2 that come to mind are power antenna being stuck (odd that the sound would last so long but I have seen this several times in vehicles as the culprit of a phantom whirring noise) or possibly air suspension if the package is installed.

Now if we consider only the engine not starting, there are a few possibilities.

1. Not getting air/fuel for combustion a. Valves could be a factor
2. Not getting spark for ignition
3. Starter not actually turning motor

You said the starter and power checks out, so we can theoretically eliminate #3.

It is possible that it's not getting air/fuel, but that would usually have other attributes as well.

If it's not getting sufficient spark (little or none or wrong timing) it may also not start (or worse).

What it comes down to in my personal experience debugging no-start scenarios is what does the motor sound like. Is it a dry raspy spinning sound or a wet chugging?

Answer 2

The sound by the engine is the starter spinning. Because you have had the battery tested, I am guessing the starter solenoid (part of the starter) is defective and the starter needs to be replaced.

If the solenoid isn't working, the starter will spin but not engage the engine.

Answer 3

If your car is turning over, and your battery checks out, then I would guess that your battery, starter and solenoid should all be fine. Because there is a humming sound coming from the back, I would also look at the fuel pump. An engine needs two basic things to run, fuel and spark. If you take away either one, it won't run. I would also guess that its not a fuse because if the fuel pump is making noise then it has power. Its an older car so the fuel filter could be clogged as well.
One more thing, if your car has auto leveling suspension, it might also make a noise but if it is trying to level a car that has sat still, you have other problems.