I took my Blazer to the shop today because I had a few issues. One was I had this feeling my fuel pump was on its way out. Just a few things like I could hear it whining sometimes but not others then it was hard starting sometimes.
So I took it up to the shop that does my work here in Arizona. They hooked up a scanner that read pressure & bleed off. Those appeared to be OK, then the tech switched this scanner to a different mode & it would read the electrical pulse of the pump motor. Then the truth showed up instead of a nice smooth pulse it was all over. Kind of like an EKG on your heart. Well bottom line the pump was starting to fail. I was told it could go miles & months or maybe not out of the shop. From my experience with electric fuel pumps I knew that was a true statement so I had the pump modular replaced with a Delphi unit so I don't have to worry about it for some time.
I thought that little (it is only about 10"x!0" like a notebook) scanner was pretty neat. So the next $15,000 I have to invest in scanners I think I'll buy one.
So bottom line now they can tell you pretty much right on if your fuel pump is working correctly or not. We might have to start buying health insurance for our cars to afford to keep them running.