Archer Fuel Pressure, typical or tell the owner?

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San_Diego_Pilot
The usual Archer II that I rent was booked up yesterday so I rented a relatively new Archer III, only about 1,400 hrs on it

My question is: In cruise the fuel pressure was at the very bottom of the green band, I would say maybe a millimeter or two above the red low end mark. Switching tanks didn't resolve it. This was with the fuel pump off since that is what is called for in the cruise checklist. I did toggle the pump on and it went back to a typical mid scale indication

What's odd is, on the second leg of the trip the fuel pressure was in the middle of the green band, again at cruise with fuel pump off

The older Archer II that I usually fly stays about mid level, with the fuel pump only having a small effect on fuel pressure. I've never seen the fuel pressure gauge be that low, especially in cruise, in any Pipers I've flown

**So, would you tell the owner, or since it stayed with the green band that's just typical for the newer Archers?** The other peculiarity, when it was near the bottom of the scale it was jumping around a bit. The plane gets flown a couple hours a week so it doesn't sit. And yes I sumped both tanks and the gascolator
 
If something is different with the fuel pressure, it definitely merits looking into. I suspect an air leak somewhere (primers are usual culprits).
 
The usual Archer II that I rent was booked up yesterday so I rented a relatively new Archer III, only about 1,400 hrs on it

My question is: In cruise the fuel pressure was at the very bottom of the green band, I would say maybe a millimeter or two above the red low end mark. Switching tanks didn't resolve it. This was with the fuel pump off since that is what is called for in the cruise checklist. I did toggle the pump on and it went back to a typical mid scale indication

What's odd is, on the second leg of the trip the fuel pressure was in the middle of the green band, again at cruise with fuel pump off

The older Archer II that I usually fly stays about mid level, with the fuel pump only having a small effect on fuel pressure. I've never seen the fuel pressure gauge be that low, especially in cruise, in any Pipers I've flown

**So, would you tell the owner, or since it stayed with the green band that's just typical for the newer Archers?** The other peculiarity, when it was near the bottom of the scale it was jumping around a bit. The plane gets flown a couple hours a week so it doesn't sit. And yes I sumped both tanks and the gascolator
I'd call.
 
Yeah, think of it this way, if you owned it and it did something odd, wouldn’t you want to know?
 
Right, just didn't know if that was typical for newer Archers, don't want to be an alarmist since I usually am in the older Archer II or the SR20. I'll drop him a line. Thanks for the replies and letting me know I'm not (that) crazy!
 
I did end letting the owner know who also said he noticed it get very low with the pump off as well.. they're going to get it looked at, so that's good!

Incidentally I did come across this YouTube video of an Archer III (clip below, I have no idea the language) and you can see his fuel pressure is also pretty much at the bottom of the green arc.. (the top right needle in the gauge cluster under the VSI) so maybe it is not usual for it to hang out at the bottom? Perhaps the design changed from the Archer II to the Archer III? The Archer II seems to always be in the middle of the gauge..

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In a case like this, why would you ever not tell the owner?
 
@airdale because it was still within the green arc and inside the Min and Max limitations. I have less time in Archer III so I didn't want to be like those people who complain about a barking dog on Airbus planes...

No harm in telling them though so I mentioned it and it will be looked at
 
If you're planning to fly the plane again it's a fair question to ask the owner for your own education. He could say, "yah, that's about where it rides" or he could say, "I better get that looked at."

Either way, anything that looks like a developing issue should be discussed. It's a good trait.
 
Have him check it out. I saw a very similar issue on a different brand of low wing plane and it was a bad engine fuel pump.
 
What was the temperature? I had a low fuel pressure issue with my Sport a few weeks ago. Less than 1/2psi with engine pump, 3psi with the electric pump. Added Prist to fuel and have seen steady 3psi on engine pump. My temps were 10 to 15F when I had low fuel pressure. Engine O-320 green arc for fuel .5 to 6psi.
 
Either way, anything that looks like a developing issue should be discussed. It's a good trait.
Yeah, plan on flying it again.. ultimately no harm in asking and I'm glad he's having it looked at

bad engine fuel pump.
Yes, I read on some Piper forms that it could be the engine-driven fuel pump starting to go, I believe it's a rubber diaphragm type pump where as the electric pump is different

What was the temperature?
Mid-sixties, San Diego wasn't too cold that day. Since you needed prist, does that mean you were getting small ice crystals in your fuel?
 
This is a known issue for O-360 equipped low wing aircraft. That is probably why the green arc is so wide in the Archer and in my M20C. Typically my Mooney will run 6 to 7 psi with the electric fuel pump on, drop 1 or or 2 psi when the pump is turned off after takeoff, and slowly decline as you climb, to just above the redline or maybe around 2 psi at 6,000-8,000 feet. After level off and cruising for a while, it will usually creep up to around 3 or 4 psi. I have no idea why this is so, but it has been discussed extensively on the Mooney blogs.
 
If the engine is running fine and the airplane is flying fine, most likely a gauge/indicator problem. Not like that hasn't happened before...
 
Fuel pump failing replace it !!!. There was a service bulletin on these pumps a while back that spoke of the check valves in them not being properly staked in place resulting in movement and fluctuating pressure readings which would eventually fail causing no fuel pressure. Mine failed in flight over the Chesapeake Bay several years ago giving no pressure. Engine continued to run fine I can only guess, due to full tanks gravity feeding the carb. Again I would strongly suggest replacing the pump. They are cheap and easy to install.
 
Was the jumping a flutter, or a quick jump and then a slow return? A flutter suggests a fuel pressure fluctuation. The quick-jump suggests a failing electrical component. And no, it working fine at a higher pressure doesn't negate an electrical problem, strain gauges can develop dead spots.
 
Was the jumping a flutter, or a quick jump and then a slow return?
A very slow fluctuation.. like across the span of a few seconds.. sounds similar to what @skmoore63 mentioned about his Mooney

Thanks for all the replies, I'll check back in on Thursday once we know more about it
 
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