Maybe your pump was replaced in the past and it's not the correct one, even though it fit your old sender. Some pics would help.
Perhaps a trip to the auto parts store and have them show you the L4 pump (not yours) and the 2.8 pump next to one another. Might shed some light on the problem.
spoon
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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut