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Mastertech1
Mastertech1, ASE Master Technician
Category: Mercedes
Satisfied Customers: 2261
Experience:  30 years of all phases automotive diagnostics and repair
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I replaced the gh pressure fuel pump and the car still

Customer Question

I replaced the high pressure fuel pump and the car still won't start. It cranks fine but it won't start. I checked the fuel comingout of the pump and it still isisn't just dribbling out. So that Must be just how it does that at stART UP. i tried gettimg an account with all data and there is nothing about fuel lines. Would the crank position sensor cause the car not to start? I just finished replacing the oil cooler seals which were deep in the engine. I put everything back the way it was supposed to but the thing will not start. Any ideas.at
Submitted: 11 months ago.
Category: Mercedes
Expert:  Mastertech1 replied 11 months ago.

Take a good look at the module in the fuel tank there is a float unit that in the sendor (with the fuel sending unit) that is designed to seal off the flow if the tank runs very low of fuel (this is to keep the system from getting air locked) and if it gets stuck, which they do, it will not allow fuel to be picked-up, you can add fuel it will not make a difference! Remove sendor module and free-ip float on bottom of unit, or remove,float and needle and seat Thanks Have a Merry Christmas!!

Customer: replied 11 months ago.
There is plenty of fuel coming from the tank. Its the high pressure fuel pump that isn't pumping much fuel. I get sufficient fuel to the fuel filter that is located in the engine. I am wondering if the camshaft position sensor is not working properly. I understand that there is a solenoid on the high pressure pump that is controlled by the cps and that the solenoid might stay closed if the cps isn't working properly. Is that a possibility?
Expert:  Mastertech1 replied 11 months ago.

Have you checked to see if there is any codes stored in the computer? Yes you could have sensor issue, or a fuel solenoid issue (fuel cut solenoid, this is what shuts down the engine when you turn the key-off, It cuts off the fuel supply to the injection pump so the engine shuts off, If solenoid is bad, or voltage to the solenoid, then it wont start!

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