High Fuel Pressure - IO-540

My fuel pressure alarm went off today because the fuel pressure exceeded the upper alarm limit I had set in my VP200 (fed by GRT EIS).

Here is a graph of the hour long flight Fuel Pressure is the green line.



As you can see, the pressure is quite erratic on the high side upon startup, for the climbout, and for a few minutes after and then settles out to the normal range. It spikes once over 45 lbs just at the beginning of runup, and again over 40 lbs as we begin cruise.

I looked at graphs of previous flights and looks like it started acting up 2 - 3 hours ago and has been getting worse. I suspect the sending unit is the problem, or connections to it, but is there anything else that could cause this? I can't imagine the fuel pump actually putting out this much pressure but..........................???

The boost pump is on only for a couple minutes during climbout and again during landing.

First I would check to see if it happens only when the boost pump is on, only when the boost pump is off or regardless of the boost pump. If regardless, or when the boost is off, then I would certainly expect a sender. It could be a loose wire or a bad ground.

I agree with Jesse. Also, the GRT senders seem to fail in the mode you are seeing fairly regularly. I have replaced a couple of them in the last five years.