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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53904
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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85 mercedes sel 500, car is hard to start when cold, when

Customer Question

85 mercedes sel 500, car is hard to start when cold, when starts runs very rough, engine will nor rev up til about 5-6 minutes, then it runs great cranks right up the rest of the day,, when cold, pour littlg gas in tb, cranks right up, runs great,, have replaced gas filters, fuel pressure is a steady 85 lbs,, thought i was apretty good mechanis, but this has stumped me, thanks danny after initial start car runs beautiful
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, welcome to Just Answer. My name is***** are you taking your fuel pressure reading?

Expert:  Marty replied 1 year ago.

You need to be taking it between the top of the fuel distributor and the warm up regulator. The fuel pressure should be approximately 30 psi when the car is cold and rise to over 50 psi when the car is at operating temperature. If the pressure never drops to 30 psi you will need to replace the warm up regulator.