High Fuel Pressure

[Mark Anderson]

On my 61 250 carb engine, after having the electric pump replaced I am having fuel pressures intermidiately above 5 psi on my JPI 930 wich causes it to flash a warning of high fuel pressure. The highest i have seen it is 5.3. This happens even with the electric pump off. Before replacing the pump i would often get high fuel pressue in the descent if the electric pump was on. The reason I had the pump replaced was that I was experiencing very low fuel pressure in the climb to the point the engine stumbled a couple of times. My A&P said the bad diaframs in the electric pump was the cause of this problem even though they were not operating at the time of the problem. The engine is running great and the pump replacement seemed to fix my problem. Although the flashing high fuel pressure on the JPI is annoying. My A&P tested the fuel pressure with a gauge ans said it reads exactly the same as the 930. Any ideas how to fix this?

Thanks

Mark Anderson

[N3322G]

Mark,

For decades the electric fuel pressure gauge has been the most electrically sensitive instrument in the Twin - through three different gauges. If it were me, I'd check that all is grounded according to the JPI manual. I can't even recall how many problems checking the grounding on the Twin as solved but it has been a bunch.

Perhaps even easier is downloading the JPI data and looking to see if the fuel pressure fluctuation corresponds to any change in engine perfroamcne. Easy to do if you note the time of a fluctuation. This is even less expensive than checking grounds and will help to diagnose if it is a gauge or mechanical issue.

Please post the results so we can all learn from your experience.