Having a frustrating problem with a 220SEb. Car sat for a while, obvious isues in fuel tank. Removed tank and had it coated, rebuilt fuel delivery pump, (have done more than 10), flushed lines, changed filter in canister. Car cranked and ran after about 15 seconds, drove it, ran good, idled good. Next day car cranked and ran for about 30 seconds, developed a lean miss and shut off, would not restart. After about 15 minutes same thing. Figured trash blocking rebuilt pump, took apart, no problem. Disconnected return line to tank and tested flow, which was good. Still same result. Disconnected metal fuel line to cold start valve and hooked up pressure gauge. Initial pressure 12 psi, drops off quickly to zero. Installed late model pump from C220, same pressure, same result. Blocking the return line partially, was able to raise pressure to about 40psi and car would continue to run. Talked to Gus and he said there were no pressure regulators in system, just dampners, pump takes what it needs out of "flow through". What's going on here?