W220 S55 AMG Kompressor won't start

[Dave Brock]

2003 W220 S55 L AMG Kompressor

Driving along and I lose all response from the accelerator pedal. As I pull in to the side of the road it sits idle fine so I pull away again. 5 minutes later it happens again only this time when I stopped so did the engine.
It hasn't started since. Just turns over.
No warning lights.
No fault codes (cheap generic obd reader).
Plenty of battery power.
Camshaft position sensor replaced (didn't solve it).
Getting spark and power to the injectors (so I assume that means the crank and cam sensors are working fine) but no fuel pressure (pushed the pin in the pressure check valve and nothing).
Fuel pump relay and fuse beneath rear seat are fine.

What's next?
Is there any other relays or fuses in the way or any module that controls the fuel pump? I've read online somewhere that the AMGs have a secondary pump relay but I can't find any details on location.

Any help much appreciated.

 

[m2287]

Sounds like throttle position sensor to me although I don't think that would make it refuse to start...

 

[E55BOF]

If there's no fuel pressure then the fuel pump isn't pumping. With those symptoms, I'd suspect it was partially seized the first time, and gave up for good the second time. If you can get at it, a direct power supply to the pump positive terminal will tell you if it's serviceable - it will pressurise the fuel rail. Is the fuel pump in the tank on these, or more easily reachable?

 

[Dave Brock]

Forgot to say, the throttle is working fine too. The fuel pump is underneath. A sod to get at with the car quite low and parked bedside the pavement but I have got to it.
With the ignition on (pre turning over) will there be constant power at the pump or does it just run for a few seconds to prime the system? I only ask as I was on my own when testing it for power. Turned ignition on, crawled under car and then got test probes onto the terminals to find I had no voltage.

 

[Auto-mobile]

There will be 12v for around 3 seconds.

 

[Dave Brock]

There will be 12v for around 3 seconds.

Looks like tomorrow I'll be calling on a mate to help.

 

[E55BOF]

One of you turns on the ignition, the other checks the fuel rail to see if it's pressurised. If not, if you can reach it, a direct feed from the battery to the pump's positive terminal - or a decent battery charger to both terminals; that's how I checked on my n/a E55 - will reveal whether the pump runs at all.

 

[Dave Brock]

Solved the issue (well, diagnosed it). Faulty fuel pump. A swift "engineer's tap" and it came back to life. New one and filter on order.

 

[E55BOF]

Thought so. Glad you got it solved.