W203 turns over but won't start

[Scampi1812]

My wife took our beloved C180 Kompressor (1995 W203) shopping at the weekend. Her last stop was at a supermarket, where she put petrol in and then moved to the parking area to do her shopping. When she returned, the car simply wouldn't start. All the dash lights come on. The engine turns over, but it won't start. My first thought was that she'd filled with diesel instead of petrol, but this is apparently impossible with the filler nozzle which prevents this.
Has anyone any ideas? I'm thinking fuel pump, but I feel it's strange that a pump would go instantly with no warning signs. I've checked the fuel pump fuse and relay and both appear to be fine.
Any help or pointers would be gratefully received.

Thanks.

 

[markjay]

If you ruled-out misfuelling, then the typical reasons why the car would crank but not start are crank position sensor, camshaft position sensor (there are two), oil-in-loom (camshaft position sensor), or timing gear failure (on the M271). But there are other possible causes... STAR is needes.

 

[mersum1es]

as above plus fuel pump/ pump relay

 

[Scampi1812]

Thanks, guys. A number of options there.
As I said, I checked the relay (just put 12v to it and heard it click), but would any of the options happen instantly with no warning? As I said,the car drove perfectly, right up to her stopping to shop, but then wouldn't start the minute she tried after leaving the supermarket.

 

[markjay]

Also clogged fuel filter (should be replaced every 4 years / 40,000 miles).

But statistically speaking... fuel-related issue is still the most likely culprit.

Diesel instead of petrol?

Contaminated petrol?

Water in the garage's petrol tank?

The last two would have affected other cars though.

Etc.

 

[MrGreedy]

I had Crank sensor fail like this on me. Then a day later it worked. Then a week later it failed for good. Cheap part to replace though, so worth a try?

 

[MrGreedy]

I had Crank sensor fail like this on me. Then a day later it worked. Then a week later it failed for good. Cheap part to replace though, so worth a try?