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My last two flights have seen some irregularities on my fuel pressure read out. The problem occurs during climb out after I have switched off the electric boost pump and no where else during the flight (I.e. I Can't recreate the issue on the ground during normal run up). Here is what happens: -Fuel pressure slowly drops once the electric pump is turned off (from 22psi all the way down to the bottom of the Green Arc ~15psi) -Once the electric pump is turned back on the pressure comes back up to about 24psi -I tried switching tanks and no luck, the issue is persistent on both sides. -Once I reach cruise altitude and pull the prop back/lean the fuel, the fuel pressure remains steady (22psi) without the electric pump on and I have no further issues My assumption is that the mechanical fuel pump is going out and can't handle the pressure requirements when I am at full throttle and prop but I would like to see what the Mooney verse had to say about this. BTW: IO-360 in a 1976 M20F

My vac pump died about a month ago and a week later I took it for Annual. Sure enough, pump disintegrated. The pic shows the flight (actually, my FR) where the pump failed, then the flight home from Annual with the new pump purring perfectly along at 5.5 or so, and then the flight last week where I kept getting vac warnings on my MVP-50 (4.5-5.5). Is this how a regulator goes south? I have not pulled the cowling and looked at anything yet. I have the full-monty Brittain system (Step, PC and 3-axis A/P). I also have the big filter that protects the system from a disintegrated pump.

Hey Guys....... I need some help with a fuel pump problem. Just prior to my annual inspection I noticed when I ran the fuel pump on low it would run the pump for a few seconds then stop..... High seems to work just fine. I reported the problem to my mechanic and he send out for a new/rebuilt pump. Same problem after replacement.... This is the email I got after the new replacement pump was installed ...... "We installed the fuel pump, Thursday, and, Friday, found the low side pressure to be way higher than what is stated in the manual. We attempted to adjust the output by adjusting the boost pump regulator (it is essentially a voltage regulator) as described in the manual and were unable to get a consistent reading. We contacted tech support, Monday, and they indicated that rarely the regulator fails, but oddly enough have come out with a retrofit kit that removes the current style regulator and replaces it with a “new” style. The kit has a 120 day lead time and is $1700. I then contacted another Mooney service center to see if they had any leads on the old style regulator or had the components necessary to assemble a retrofit kit, no joy. They recommended contacting another service center in Texas, who happens to repair the “old” style regulators. I have sent it to them for evaluation and quote for repair. By talking with other techs they verified that we had a pump issue. So it is good that we put the gauge on it to verify pressure as to not wear out another pump." This is email I got today.... "We received the pump back late Tuesday and are having the same issue(s). Pump works when voltage is set high for high output, but when trying to adjust to low output the pump doesn’t operate." Does anyone have any experience with this issue? I have not been able to fly for about 6 weeks .... I miss my Mooney! Thanks for the help Mike Johnson Mooney M20R N871TX