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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3567
Experience:  Qualified Mercedes Benz Diagnostic Technician - 20+ years experience - Workshop Foreman for Mercedes
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GL450 2007 cranking but won't start, tried to swap fuel pump

Customer Question

GL450 2007 cranking but won't start, tried to swap fuel pump relay from working ML350 did not helped.
Has code 0521
Where else should I look further?
Submitted: 9 months ago.
Category: Mercedes
Expert:  Michael Warfield replied 9 months ago.

I wouldn't be concerned about the 0521 fault code since that will not prevent engine starting. Have been able to check to see if there is any fuel pressure in the rail? I would suggest popping off the front engine cover, unscrewing the round black plastic cap on the fuel rail, and pressing the small shrader valve to see if fuel squirts out forcefully. Here is a picture of the fuel pressure port I'm referring to.

Customer: replied 9 months ago.
Hi Michael,
thank you for your response, I was waiting 2 days without the answer and I have had mechanic fixed the car before you answered.
Expert:  Michael Warfield replied 9 months ago.

Ok great, sorry for the delay. Hope all is well!