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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 22756
Experience:  BEng hons Mech engineering, in auto industry 22 years
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1989 300SL auto ,when engine cold cuts out when put into drive

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1989 300SL auto ,when engine cold cuts out when put into drive . No problem when engine warm .Idle control valve seems to be working correctly

this sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank.

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,
Ideally measure the pressure at the inlet to the main engine fuel distributor (should be 5 to 5.8bar) and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.
Customer: replied 3 years ago.

Hi Matt ,if fuel pressure is problem would it not cut out regardless of engine temp ?

Hello Phil

not necceserily as the fuel pressure is changed by the device known as the 'warm up regulator'

this is electrically heated from a cold start and adjusts the fuel pressure to provide cold enrichment

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