"High" fuel pressure alerts

Brian,
Are you using a differential fuel pressure sensor with a pressure reference tube to the airbox, or are you using a gauge pressure sender and using the EFIS to correct for manifold pressure? Also, where is the sender located in the fuel system?  

Hi Jeff,

I'm using the UMA pressure sender PN EU-15,087/N1EU70D for my pressure sensor.  I'm not sure if that falls into either of those categories.  I am taking the feed off the engine itself.

I've attached a picture of the area where the sender is located... It's in the bottom left hand corner of the firewall.

Thanks,

That is the correct sender.  The black tube coming off the top of the sender is an air tube that runs up to the airbox so the pressure sender can reference manifold pressure.  The Rotax fuel pressure regulator references manifold pressure, so the fuel pressure sender should also.  So all is good with this configuration.

I would trace out the black tube running from the sender to the airbox just to make sure it’s not kinked or cut somewhere and is not leaking at either fitting.  And as your avionics shop suggested, you could connect an analog fuel pressure gauge for comparison, but it’s going to have to a differential type gauge and you will need to temporarily T into that black tube for your reference pressure to the temporary gauge.  If you use a standard gauge the readings will be wrong and won’t match your fuel pressure gauge.  

I think a likely problem here is that the fuel sender setup is wrong in your EFIS (and is set for the wrong sender). If it’s set up for a different sender it might give you readings like you are seeing.  What EFIS do you have? If it’s a G3X you can check this in the configuration mode.  

Also, the readings you are seeing could be accurate, but a swing in pressure of 7 PSI would not be typical.  If you are using automotive fuel the low pressure could be explained by a fuel vapor problem, but that would not explain the 47 PSI readings.  If you are using automotive fuel, you could simply try some Avgas and see if this improves.