When this is happing is the sight gage rising indicating that the fuel is indeed not returning as needed? If so and if there is good return lines and no leaks as you indicate then the only place for it to come out would be the vent hole. So again if the returns are open and no leaks are there then the pump would have to be pumping too much and overwhelming the returns. I take it from this discussion that you don't have an engine driven pump, only the electric?
Kevin1 --- In [email protected], "Bert" <stkb...@...> wrote: > > Thanks everyone for your input. Thus far, we have not solved the > problem but we have numerous good leads. Responses to the individual > who spoke up follows: > > Thanks Dan C > - I have flown for four years now, including many long cross country > trips using the electric fuel pump. Only turning it off when the red > light comes on indicating a dry line (empty wing tanks). A condition > that has always occurred at about 2:45 to 3 hours of flight. > > > Thanks John Cooper > - Having filled the tank and tested it (and all the lines) under > pressure, we are somewhat mystified. There do not appear to be any > leaks, holes, cracks, etc in the systems plumbing. > - The inability to replicate the event during static ground tests, > mystifies us as well. > > > > > Thanks Bill N1659Z > - The cap (and sight tube) are brand new. The old cap (with an > unprotected wire protrusion sight gauge) had a thin very old gasket. > The new gasket is surely making a better seal. > > > Thanks Syd > - The black rubber gasket is old and is a possible culprit. > - Yes we have verified the return line is clear. > - I'll have my A&P check the `restrictor'. > > > > Thanks - W. R. Bayne > -Yes the return line appears to go to the right wing tank (it is > clear, unobstructed) > -Yes the vents on all three tanks are clear > -I am looking up the old records for fuel system modifications as you > suggest. I have been flying this plane regularly for four years yet > never experiencing this problem (except for a frequent fuel smell). > Changes made over a decade or longer in the past should not be first > evidencing a problem now. > -Your idea about the "seal" being the culprit, seems worth pursuing. > The seal looks good, but is VERY old. I do know fuel was filled > above the the neck joining point during our test yesterday. > -I don't know what PSI the A&P used. > > > Thanks everyone. > > Bert Hampton >
