No fuel pressure

[AlfredE]

Hi Pelican, I have a w203 C200, 2002 kompressor. I recently find that the car cranks but refuses to start. I checked the fuel pressure and realize fuel wasn't coming to the fuel rail. I subsequently checked the fuel pump and realized that they was no voltage at the fuel pump, however, once the fuel pump was plugged out, there was a voltage reading at the connector at the fuel pump. I had the car scanned and the technician said I had a faulty fuel pressure sensor. Unfortunately, I cannot seem to locate a fuel pressure sensor for the 2002 C200, neither can I locate the faulty one on the car, can you help me.

[W126world]

Fuel pump relay

[tjts1]

There is no fuel pressure sensor. Your pump is toast.

[muller]

I agree with tjts1, if you're getting voltage to the pump with no load (i.e. the pump is disconnected) then no volts at load, this means your pump is shorting.

[Graham]

It depends on how the voltage is being tested. When you first turn the key on, the ECU tries to run the pump briefly by actuating the relay and then turns off. If pump doesn't run, it could be a problem with the pump, or the relay, or the ECU and it's inputs.

I would try disconnecting the pump or just removing the pump relay then apply 12v to the pump itself. That will tell you if the pump is faulty or not.

I would also check that you have spark - get that easy check out of the way.

It could be a completely different problem. Maybe the crankshaft position sensor? You can check that by watching rpm with an OBD2 meter or app while cranking. You should see the cranking rpm - maybe about 200rpm.

I went through something like this on our e320. Turned out to be an ecu related problem.