i wasnt able to pinch any lines on my 420sel as they were so hard and old. i tighened the washers down snug at first and spot checked for leaks and tightened as needed. One more turn of the wrench after that proved enough. If you did not purchase new rubber fuel line and yours is old and hard, do not do the work on a sunday afternoon like i did when no parts are available. especially if you rely on your car to get to work in the morning.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual