912ULS Low Fuel Pressure on Climb-Out

With a low wing aircraft, you are pumping fuel Uphill when climbing and downhill when descending.

The fuel pressure will change 1 psi for every 40 inches of rise, not including restriction losses.

I will ask the rhetorical questions, "Was your AUXillary fuel pump running at the time?"

And, "Do you have a fuel return line installed?"

Van's Aircraft has an optional upgrade that includes a higher pressure fuel pump that helps to address low fuel pressure:

https://www.vansaircraft.com/service-information-and-revisions/n-2018-07-12/

Bill Hertzel wrote:

With a low wing aircraft, you are pumping fuel Uphill when climbing and downhill when descending.

The fuel pressure will change 1 psi for every 40 inches of rise, not including restriction losses.

I will ask the rhetorical questions, "Was your AUXillary fuel pump running at the time?"

And, "Do you have a fuel return line installed?"

Thanks for answering Bill.  Yes, the aux pump was running, and there is a return line.  It just started doing this last week.  One thought is a bad fuel flow sensor, so we ordered a new one, but still waiting for it to come in.  I am not confident that will fix the problem as everything except climb is good.

Bob

It does not sound like a Pressure sender problem.

Are you sure that the AUX pump is operating properly?

Do you see the pressure vary with the pump ON or OFF?

I posted here a few months ago, with virtually the same problem. I have yet to get an answer here on the forum, and now a similar issue comes up again. 

As to my low pressure issue, well, it seems to have disappeared for now. I’m not 100% sure why, as the only differences have been a temperature change, it got warmer here and I found a loose hose clamp when the left card connects to the air box. I noticed soot on the air box sleeve. There are two clamps, it was the clamp at the air box side. I tightened the other three. Could this have caused the problem? 

At first I thought it was a fuel problem, I primarily use 91 octane NON Ethanol fuel, so I added 100LL, the low pressure readings were still present. 

As I stated, the issue on climb out has vanished on the few flights I’ve had recently, now that the temps here in the northeast have risen. I’m keeping a close eye on it for now.