Piper Arrow IV fuel pressure

[MC]

Does your fuel-pressure gauge fluctuate noticibly ?

Mine vibrates at about a 3Hz rate between the
middle and bottom of the green-band.
Engine runs fine...

Turning-on the electic pump reduces the amplitude of
the swing and stablizes it at around mid gauge.

Is this 'normal' ??

[Bob Chilcoat]

The fuel pressure gauge on our '74 Archer is rock solid. So was the gauge
on the Arrow III I flew once, and on every other Cherokee I've ever flown.
I've never noticed fluctuation on the fuel pressure gauge. Don't ask me
about the load meter (ammeter), though.

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney (Or Kerry, for that matter) to love
America

"MC" > wrote in message
...
> Does your fuel-pressure gauge fluctuate noticibly ?
>
> Mine vibrates at about a 3Hz rate between the
> middle and bottom of the green-band.
> Engine runs fine...
>
> Turning-on the electic pump reduces the amplitude of
> the swing and stablizes it at around mid gauge.
>
> Is this 'normal' ??

[Aaron Coolidge]

MC > wrote:
: Does your fuel-pressure gauge fluctuate noticibly ?

: Mine vibrates at about a 3Hz rate between the
: middle and bottom of the green-band.
: Engine runs fine...

: Turning-on the electic pump reduces the amplitude of
: the swing and stablizes it at around mid gauge.

: Is this 'normal' ??

Every Arrow I've ever flown (three different 180 HP versions) does this.
Don't know if it's bad or good, they were rental AC.
--
Aaron Coolidge

[PaulH]

MC > wrote in message >...
> Does your fuel-pressure gauge fluctuate noticibly ?
>
> Mine vibrates at about a 3Hz rate between the
> middle and bottom of the green-band.
> Engine runs fine...
>
> Turning-on the electic pump reduces the amplitude of
> the swing and stablizes it at around mid gauge.
>
> Is this 'normal' ??

My 69 model does not fluctuate. Air in the line?

[Roy Page]

Check the gascolator for a leak !
Had a similar problem on my Archer II.
In climb the fuel pressure gage fell back to midway between the red and the
center point of the green arc.
After leveling off the indicated pressure slowly came up.
With the electric pump on the variation was significantly less or stable at
higher indicated pressure.
I foolishly flew the bird halfway across the country like this.
Back at home, my AP found the gascolator top seal was unseated and leaking.
New seal fixed the problem - now have normal indicated fuel pressure with or
without the electric pump.
Normal for this and our club's Archer is needle in the center of the green.
Don't accept this varying pressure something is adrift.

Good Luck,

Roy



"PaulH" > wrote in message
om...
> MC > wrote in message
> >...
>> Does your fuel-pressure gauge fluctuate noticibly ?
>>
>> Mine vibrates at about a 3Hz rate between the
>> middle and bottom of the green-band.
>> Engine runs fine...
>>
>> Turning-on the electic pump reduces the amplitude of
>> the swing and stablizes it at around mid gauge.
>>
>> Is this 'normal' ??
>
> My 69 model does not fluctuate. Air in the line?

[[email protected]]

This sounds like something that needs immediate attention. My guess would
be a leaking (or otherwise faulty) engine driven fuel pump or possibly a
leak in the gascolator.

On our Arrow IV, the fuel press gauge is stable in the middle of the green.
It moves just a bit (to higher pressure) when the electric pump is turned
on.

I think in your case a visit to the A&P is definitely in order. The good
news is that the problem is most likely not going to be terribly expensive
(in aviation terms) to fix.

Please let us know what you find.

--
-Elliott Drucker

[MC]

Roy Page wrote:
> Check the gascolator for a leak !
> Had a similar problem on my Archer II.
> In climb the fuel pressure gage fell back to midway between the red and the
> center point of the green arc.
> After leveling off the indicated pressure slowly came up.
> With the electric pump on the variation was significantly less or stable at
> higher indicated pressure.
> I foolishly flew the bird halfway across the country like this.

I did the same thing. <g> (although in Oz it can be a long
distance between licenced mechanics.)

> Back at home, my AP found the gascolator top seal was unseated and leaking.
> New seal fixed the problem - now have normal indicated fuel pressure with or
> without the electric pump.
> Normal for this and our club's Archer is needle in the center of the green.
> Don't accept this varying pressure something is adrift.

I too had a slight gascolator air leak on my last trek, (which made
for a somewhat lean mixture), but the fluctuating pressure predates
that problem for several inspection cycles.


> "PaulH" > wrote in message
> om...
>
>>MC > wrote in message
>...
>>
>>>Does your fuel-pressure gauge fluctuate noticibly ?
>>>
>>>Mine vibrates at about a 3Hz rate between the
>>>middle and bottom of the green-band.
>>>Engine runs fine...
>>>
>>>Turning-on the electic pump reduces the amplitude of
>>>the swing and stablizes it at around mid gauge.
>>>
>>>Is this 'normal' ??
>>
>>My 69 model does not fluctuate. Air in the line?

[MC]

wrote:
> This sounds like something that needs immediate attention. My guess would
> be a leaking (or otherwise faulty) engine driven fuel pump or possibly a
> leak in the gascolator.
>
> On our Arrow IV, the fuel press gauge is stable in the middle of the green.
> It moves just a bit (to higher pressure) when the electric pump is turned
> on.
>
> I think in your case a visit to the A&P is definitely in order. The good
> news is that the problem is most likely not going to be terribly expensive
> (in aviation terms) to fix.
>
> Please let us know what you find.

Some feedback..
I hade my LAME replace the seal in the gascolator.
The fuel pressure gauge now indicates a tad below mid-scale
with only a little fluctuation during flight.

Thanks for the responses everyone.., greatly appreciated.

[Roy Page]

Well it does seem that all us PA28 cowboys want to stop riding the horse as
soon as we see in flight variations in fuel pressure reading.
Thanks for the feedback.

Roy

"MC" > wrote in message
...
> wrote:
>> This sounds like something that needs immediate attention. My guess
>> would
>> be a leaking (or otherwise faulty) engine driven fuel pump or possibly a
>> leak in the gascolator.
>>
>> On our Arrow IV, the fuel press gauge is stable in the middle of the
>> green.
>> It moves just a bit (to higher pressure) when the electric pump is turned
>> on.
>>
>> I think in your case a visit to the A&P is definitely in order. The good
>> news is that the problem is most likely not going to be terribly
>> expensive
>> (in aviation terms) to fix.
>>
>> Please let us know what you find.
>
> Some feedback..
> I hade my LAME replace the seal in the gascolator.
> The fuel pressure gauge now indicates a tad below mid-scale
> with only a little fluctuation during flight.
>
> Thanks for the responses everyone.., greatly appreciated.