This is a long story, but I seriously need some help. In September 2016 my 2002 Volvo S60 just stopped working. I could not figure out what the problem was (I'm not that great with cars), so I took it to a mechanic. I had 3 mechanics turn away the car cause they refused to work with European make. I finally hauled it clear up to my nearest Volvo dealership. They didn't know exactly what the problem was, but decided to charge me $1000+ to replace the throttle chamber. Lo and behold, the car still doesn't work. So I pick up the car and take it to one last mechanic. He has no idea what to do.

So now I am here almost 6 months later with a Volvo that won't start and no one knows why. The symptoms right now are the car will start, run for about 6-7 seconds, and then shut off. All the electric is still on, but the engine shuts off. Some say it is the immobilizer, others say its a problem with the fuel pumps. I really would like to salvage that car and it has been my favorite car to drive, but unless I can figure out what is wrong with it I'm going to have to sell it for parts.

In any case, if anyone has any suggestions I really need some help!

 

Those mechanics that don't know what to do,-have they even checked anything?
What exactly did they do?

Also, learn a lesson from those mechanics who wanted to replace the throttle body.
That is NOT diagnosing,-it's emptying wallets.
If parts were free, you could throw parts at the problem and sooner or later the car would be fine.
Since parts are not free, you need to get started doing some diagnosing.
Diagnosing is using your brain and testing parts, for finding out not so much what doesn't work, but what actally works.
After a while you will have eliminated what the fault can NOT be, and then you're left with what it CAN be.

Also, what kind of engine do you have? Some engines have a fuel pressure regulator and NO fuel pressure sensor while some engines have a fuel pressure sensor and NO regulator. Your first task is to find out which of these fuel systems you have.

Let's assume you have an engine with a pressure regulator and no sensor.
So, start with doing some thinking: -What does an engine need to run?
Fuel, spark and compression.
It starts, so obviously it gets all three things until a few seconds has passed, then it looses either fuel, spark or compression.
Is it likely that it looses spark after those few seconds? -No.
What about compression? -No.
Fuel? -Yes, if the the fuel pump relay enables priming but not running it would start and then die.

So,-first thing first,-get inside the car and insert the key. Turn the key one notch.
You should hear a climate control servo motor running for a second.
Insert the seatbelt in the seat your sitting in to make the alarm shut up, it's important to be able to hear the fuelpump running or not.
Now, turn the key another notch. Dashboard lights should come on, and you should hear a faint sound from the backseat.
That's the fuelpump priming the fuelrail. It should stop after one or two seconds.
Now there should be fuel pressure in the fuel rail, and it should hold for quite some time before bleeding off.
At one end of the fuel rail there's a little valve.
Find it and unscrew the plastic cap and depress the needle.
It should squirt gas and then stop.
In reality, there's no need for you to do this test, since we already know the fuel pump is priming, otherwise the engine would never start at all, but do it anyway just to get started.
Next step is verifying the fuel pump relay. Obviously it enables priming, but maybe not running.
This is how the relay works:
Ignition on - the relay starts the fuel pump and stops after a couple of seconds.
ignition key in cranking position - the relay starts the pump and lets it run continously even after you let go of the key.

So, how to check the relay? There are a number of ways you could do this.
You could listen to the fuel pump when the engine is running, IF you can hear it at all above the engine noise. Another way is to tear out the backseat and measure voltage across the contact on top of the fuel tank, or you could measure voltage on the fuel relay itself.
The last method requires you to know the relay pin-out and finding a way to access the relay pins while the relay is in the socket.
The easiest way is to replace the relay with a known good one, and if the engine doesn't die after a few seconds the fault is found,-problem solved.

To sum it up: I suspect the fuel pump relay is the cause here. It obviously starts the fuel pump to prime the fuel rail, but fails to make the pump run after the engine is running.

Replace the relay, and then get back here and let us know what happened.