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Old 03-04-2010, 01:59 PM
ctaylor738 ctaylor738 is offline
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Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,316
You are testing by connecting the gauge between the fuel dist. and the warm-up regulator, correct? You shut the valve on the WUR side and measure system pressure. Then you open the valve to measure control pressure.

70 psi system pressure is good. Your control pressure with at cold engine should be 21-24 psi and warm about 55 psi. If you have 70 psi cold, the car probably won't start. Why? Because the high pressure will not allow the air sensor plate to deflect enough for the piston in the FD to move, hence no fuel.

The most common cause of this is the mesh filter in the WUR inlet is clogged. You can remove the fitting and fish the filter out with a pick and clean it. There are several layers of mesh and they all need to be clean.

You can try cranking the engine while someone pushes the sensor plate down about half an inch with a stick. Dont get your face close because you may get a backfire!
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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