High Mechanical fuel pressure.

[DrBill]

Went to go fly today and my mech fuel pressure is 50psi. Was aok on 7/18. This obviously causes rich running and it quits at idle.

Any ideas ?  This engine had major in Jan and now has less than 20 hrs on it with the fuel system overhauled at same time.

Bill

 

[N201MKTurbo]

That pressure is set by the spring in the fuel pump. The only thing that I can think of that would make it do that would be high crankcase pressure which would act like a stronger spring in the pump.

One other thing would be the shaft in the pump that lifts the diaphragm could be jammed and driving the diaphragm instead of letting the spring push it up. (bad pump) 

Edited August 9, 2016 by N201MKTurbo

[Guest]

Connect a test gauge to the fuel system to verify the problem first.  

Clarence

[Yetti]

what device is saying 50 PSI?  could be a bad transducer.   Check downstream of the pump for blockage.  Say the screen at the servo.  old or new fuel lines?

[DrBill]

The dash fuel pressure gauge shows 50 with mechanical pump (engine running) and properly at 30 with electric pump only (engine off).

So tomorrow my A&P and I will try to pull the pump.  All new fuel system since had full Overhaul in Jan-Feb.  pump is under warranty from engine builder.

Was ok on 7/18.  and high yesterday, I understand it is a common mode of failure when the mech pump fails.

Thanks for all the responses.

Bill

 

[DrBill]

engine builder (triad aviation) giving me new pump under warranty. and will help with R&R labor !  YEA!

big job to pull pump, will do another day.

Bill

BTW the fuel pressure on mech pump is governed by  return spring under diaphragm.

[carusoam]

There is another thread discussing fuel pressure related to a C.  Typical range for the O360 is only 2-6 psi or so...

looks like somebody had received an E's pump for their carb'd engine.

Sharing similar story,

-a-

[DrBill]

I just read that thread and agree that he's got an electric pump for an injected engine.

Bill

[N201MKTurbo]

FWIW, if you want to void the warrantee on the pump, just chip the sealant off the pressure regulator, remove the little plate that says not to adjust and adjust the pressure to whatever you want....

 

[Guest]

9 hours ago, N201MKTurbo said:

FWIW, if you want to void the warrantee on the pump, just chip the sealant off the pressure regulator, remove the little plate that says not to adjust and adjust the pressure to whatever you want....

 

and hammer out a new data plate to "correct" the part number. Or just bend the needle on the gauge to a more pleasing value.

Clarence

[DrBill]

On 8/14/2016 at 5:54 AM, M20Doc said:

and hammer out a new data plate to "correct" the part number. Or just bend the needle on the gauge to a more pleasing value.

Clarence

The main problem is the engine runs like crap with the high pressure and is difficult to stop !  Mag drop went from 25 before to 110 after pressure change. So I'm looking forward to the lower pressure to get back in the air.

Bill

 

[DrBill]

M20Doc was  right.  Today we went out to replace pump and I said lets verify problem first.  So I started it up and sure enough c 45psi.

My A&P walked around and said no smoke, should be smoking at that pressure so we drove around the a/p for a while and back to hangar shut it down.

DUH  15 PSI at shutdown. So he grabs a couple of wrenches and dives under the panel.. "WHATS IT NOW" he yells, "15 " I say.  "Disconnected" he says.

SO saves us a ton of work, he pulls the gauge and now i need to send for repair.

ANY SUGGESTIONS ?

thanks.

BILL

[eman1200]

On 8/14/2016 at 5:54 AM, M20Doc said: and hammer out a new data plate to "correct" the part number. Or just bend the needle on the gauge to a more pleasing value.

Clarence

The main problem is the engine runs like crap with the high pressure and is difficult to stop !  Mag drop went from 25 before to 110 after pressure change. So I'm looking forward to the lower pressure to get back in the air.

Bill

 

Bill, wouldn't this indicate an actual issue and not "just a gauge issue"?

[mooniac15u]

20 hours ago, DrBill said:

M20Doc was  right.  Today we went out to replace pump and I said lets verify problem first.  So I started it up and sure enough c 45psi.

My A&P walked around and said no smoke, should be smoking at that pressure so we drove around the a/p for a while and back to hangar shut it down.

DUH  15 PSI at shutdown. So he grabs a couple of wrenches and dives under the panel.. "WHATS IT NOW" he yells, "15 " I say.  "Disconnected" he says.

SO saves us a ton of work, he pulls the gauge and now i need to send for repair.

ANY SUGGESTIONS ?

thanks.

BILL

Maybe Captainglen would sell you the one he removed.  It sounds like it was working correctly although not the correct part for his plane.

 

[Guest]

23 hours ago, DrBill said:

M20Doc was  right.  Today we went out to replace pump and I said lets verify problem first.  So I started it up and sure enough c 45psi.

My A&P walked around and said no smoke, should be smoking at that pressure so we drove around the a/p for a while and back to hangar shut it down.

DUH  15 PSI at shutdown. So he grabs a couple of wrenches and dives under the panel.. "WHATS IT NOW" he yells, "15 " I say.  "Disconnected" he says.

SO saves us a ton of work, he pulls the gauge and now i need to send for repair.

ANY SUGGESTIONS ?

thanks.

BILL

Try Keystone Instruments in PA.  They do a bunch of classic instruments.

Clarence

[Brandontwalker]

M20Doc was  right.  Today we went out to replace pump and I said lets verify problem first.  So I started it up and sure enough c 45psi.

My A&P walked around and said no smoke, should be smoking at that pressure so we drove around the a/p for a while and back to hangar shut it down.

DUH  15 PSI at shutdown. So he grabs a couple of wrenches and dives under the panel.. "WHATS IT NOW" he yells, "15 " I say.  "Disconnected" he says.

SO saves us a ton of work, he pulls the gauge and now i need to send for repair.

ANY SUGGESTIONS ?

thanks.

BILL

I have one for sale if interested. Make an offer.

Sent from my iPhone using Tapatalk

[Yetti]

On 8/14/2016 at 4:54 AM, M20Doc said:

and hammer out a new data plate to "correct" the part number. Or just bend the needle on the gauge to a more pleasing value.

Clarence

Is that why my father gave me all those number and letter punch sets...  snicker  :-)

[DrBill]

I'm having the original one fixed for $200 at Century Instruments where the flight school at my airport has theirs done.

I would have made an offer for Brandons but for some reason I did not get notified of new posts on this topic. I did look in the classifieds for one before he posted.

I wanted to go to triple tree on sat and I could  have put his in by then.  BUMMER.

Thanks for all the replies.

Bill