Bearhawk Aircraft Bearhawk Tailwheels LLC Eric Newton's Builder Manuals Bearhawk Plans Bearhawk Store


No announcement yet.

Lycoming engine driven wobble pump, fuel pressure fluctuating

  • Filter
  • Time
  • Show
Clear All
new posts

  • Lycoming engine driven wobble pump, fuel pressure fluctuating

    I have had two engine driven fuel pumps on my engine in the last 700hrs. Both wobble pumps. The first one failed in the mechanism (not the normal gasket).

    Normally the fuel pressure is steady, but I noticed that both old and new pump occasionally fluctuate between about 23 (or 25) and 27 PSI. If I apply the electric boost pump, then I see the pressure rise to about 28 or 29 PSI and the fluctuation reduces, but there is still a small fluctuation. It can keep doing this for hours. Other times, the pressure will be steady for hours on end, I can't say why.

    Can anyone comment on possible causes? Should I be concerned?
    I thought I saw a thread about this issue somewhere recently, but I can't find it.

    Fuel pressure is measured at the outlet of the engine driven pump.
    Fuel pump is a certificated part / installation.