I recently swapped the sender in my 89 740 turbo with a junk yard donor ('92) to fix the bad fuel lever sensor. I put in a new pump on the sender and replaced the return and supply hoses as the replacement sender had straight pipes coming out of the sender not 90 degree pipes like my original.

Everything seemed good for a while then my main pump became noisy and later died. I replaced it but it was still noisy.

I figured I had a bad sender so I built a test set with a pressure gauge to test some spare tank pumps I had and I would test the installed unit after I removed it. Turns out the amp draw was 2 amps DC with the pumps returning fuel back to my test bucket. With the pumps supplying pressure to a closed gauge it was 3 amps and the PSI was 15.

I then started to remove the sender and saw the supply hose had kinked! The new 180 degree bend was too much. I ended up putting in a 90 elbow and all was well.
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Paul NW Indiana '89 744 Turbo 190 K/ '90 745 turbo 145 K