I have been reading about CIS to attack the funky idle on my 380. I think you should get it to crap out and then be prepared to quickly check fuel delivery. You check this off the return hose and the spec is one liter in 30 seconds. Personally, I would have a helper jumper the relay for 10 seconds and measure that quantity against the spec.

If flow is in spec, you can stop worrying about the fittings and move on to the fuel distributor or injectors.

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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