High fuel pressure with new fuel pump

[takair]

6 hours ago, Hillard said:

Despite this issue having been around for at least six months, mooney and lycoming appear to have done nothing to resolve it.  We have just discovered this issue after starting up an overhauled A3B6 engine last week.  Everything was fine except the fuel pressure gauge is hard over to the right.  No response yet from mooney or lycoming.    

Despite it being listed on the type certificate and marketed for the 20J, the engine supplied by lycoming is incompatible with the airframe in three respects:

a) fuel pressure higher than mooney limit

b( prop oil line supplied interferes with engine mount and has to be replaced at your cost (usd500)

c) extra parts required from mooney to rig prop control cable (another usd500)

Did lycoming tell me any of this when they supplied the engine? - no.  I’ve only discovered it from mooneyspace.  

The engine supplied is not “fit for purpose” and lycoming appear to care not a jot.  I treat their statements about “customer care” as utter garbage.  

They never replied to my request to return the unused pump.  It was really a disappointing experience and it sounds like the wrong pump is still marketed for Mooney’s.  I was lucky enough to sell my pump to a Piper owner who was looking for higher pressure and the aircraft was approved for higher pressure.

[kellym]

On 12/5/2017 at 4:59 PM, takair said:

They never replied to my request to return the unused pump.  It was really a disappointing experience and it sounds like the wrong pump is still marketed for Mooney’s.  I was lucky enough to sell my pump to a Piper owner who was looking for higher pressure and the aircraft was approved for higher pressure.

After thinking about this overnight, and doing a fair amount of research...I would put at least 95% of the blame on Lycoming. They obviously changed the specification of what fuel pressure was acceptable and making a change in the product, without much if any consultation with airframe manufacturers or FAA. I found that POH or equivalent for Mooneys has contained an airworthiness limitations that includes fuel pressure gauge reading between 14 and 30 psi since 1967. I suspect that Cessna had similar limitations for Cardinal RG that uses same engine.

While the 45 psi max spec I found as far back as 1984 Lyc POH, it appears that the pump until fairly recently didn't produce above 30.

That fact alone makes thousands of aircraft unairworthy if a new Lycoming pump is installed. The best remedy I can think of is to submit a Service Difficulty report to the FAA for each and every instance.  I don't know what prompted Lycoming to make the change, but it affects the red lines on installed gauges for every engine that uses this pump...which is every Lycoming 4 and 6 cylinder normally aspirated, fuel injected engine. I don't really blame Mooney, as they have much smaller numbers involved than other airframe manufacturers and probably have little leverage with Lycoming since they switched all of their new models to using Continental engines.

 

[N201MKTurbo]

I reciently had my fuel pump overhauled. It is a rare Rajay pump. It costs 4 times more to overhaul than a standard pump. There is only one repair station on earth that is authorized to overhaul it. When it came back it made 32 PSI. Ii has sense dropped down to 30.

I suspect someone changed the spec on the spring and it is the same spring used in all the pumps. It may be the only part available to the rebuilders. 

Other than the regulatory implications. There isn’t an operational issue with the higher pressure. I reciently talked to the chief engineer for Precision Airmotive and asked him how much fuel pressure the RSA-5 could tolerate. He said it would work fine up to about 75 PSI.

[carusoam]

Another thread has an interesting note about ray jay turbo set-ups...

I believe the STC indicates a different pump with pressure output control on it...

@tomgo2 may know something about ray jay STCs...

Best regards,

-a-

[N201MKTurbo]

1 minute ago, carusoam said:

Another thread has an interesting note about ray jay turbo set-ups...

I believe the STC indicates a different pump with pressure output control on it...

@tomgo2 may know something about ray jay STCs...

Best regards,

-a-

That’s who brokered the overhaul of my pump. There is an upper deck pressure line to the pump. There is no pressure regulator.

tomgo2 doesn’t rebuild the pumps. The repair station that does doesn’t deal directly with customers.

[carusoam]

Hey Rich!

Tomgo2 is our MSer with Ray Jay STC and hardware parts. Who, Unfortunately, does not have the control of the Mooney / Ray Jay STCs...

 

Inviting @Spike Kavalench To this discussion....

Spike shared some details (today) regarding Ray Jay required (?) fuel pumps... for his M20B...

I’m trying to not accidently add improper tech details in the process of connecting people and threads....  

Best regards,

-a-

[J0nathan225]

Anyone have a remedy other than replacing the pump at owner cost?  Should I reach out to lycoming (I know some of you have tried) and/or Triad who ordered and installed the pump when the previous owner O/H'd the engine?  

What was the damage for installing the new pump? 

[takair]

1 hour ago, J0nathan225 said:

Anyone have a remedy other than replacing the pump at owner cost?  Should I reach out to lycoming (I know some of you have tried) and/or Triad who ordered and installed the pump when the previous owner O/H'd the engine?  

What was the damage for installing the new pump? 

I would try to reach out to Lycoming, even though it didn’t work for me.  Really wish they would stop selling them for Mooney’s.  3-5 hours labor seems reasonable if they’ve done it before.  Seems to depend on how crowded the back of your engine compartment is.  I like to pull the magneto, mainly because I find it easier to get the plunger out of the way.  Other mechanics do the pump with the magneto in place.

[Browncbr1]

Just for community record, I replaced the fuel pump on my io-360-a1a. 67F with rebuilt tempest LW-15473 and the fuel pressure and flow is perfect.   

Lycoming has a record of giving bad guidance for our engines.  The fuel pump is one issue and the engine timing/mag issue is another.   

[outermarker]

I'm going to replace my mechanical fuel pump this year. This thread mentions for a IO360-A1A , a Lycoming pump LW-15473. A Tempest pump 41234 is also mention to be for this engine. It seems that both pumps are being supplied by Tempest. They are both an overhauled pump. What am I missing besides about $150 if I choose the Tempest version of the Lycoming LW-15473?

TEMPEST O/H FUEL PUMP 15473

$307.00/Each

41234 TEMPEST O/H FUEL PUMP

$464.00/Each

[Will.iam]

On 3/31/2022 at 9:01 PM, outermarker said:What am I missing besides about $150 if I choose the Tempest version of the Lycoming LW-15473?

TEMPEST O/H FUEL PUMP 15473

$307.00/Each

41234 TEMPEST O/H FUEL PUMP

$464.00/Each

From what I’ve read you will be missing the headache of psi above 30 problems. 

[ArtVandelay]

From what I’ve read you will be missing the headache of psi above 30 problems. 

FYI, for me after about 30 hours this problem went away, pressure drops back down to high 20s.

[Patrick Lyons]

I visited the Lycoming booth at Airventure ( circa 2018)  with videos of my new IO-360A36B AT IDLE, TAKE-OFF AND CRUISE. Spoke with several techs.

 

1.   Lycoming will give you a lengthy dissertation.... summation... pressures bumping into 32 LBS is NOT A Problem.

2.   Lycoming is fully aware this condition exists...and if you INSIST on A SOLUTION ...YOU/I " WILL NOT BE SATISFIED" .

3.   I wish I could provide  you the Techs names and a summation of the 3 mans team's substantiations... for Lycoming's position!!!

FYI:   . Lycoming is HOLDING THEIR "COME TO WILLIAMSPORT"   pay for a seat ..for a week to learn ... April 4--8; 2022.

I agree there are other's who are flying with..and provided comments on this high oil pressure  and may  have shared a better solution than mine. 

[carusoam]

30 minutes ago, Patrick Lyons said:

I visited the Lycoming booth at Airventure ( circa 2018)  with videos of my new IO-360A36B AT IDLE, TAKE-OFF AND CRUISE. Spoke with several techs.

 

1.   Lycoming will give you a lengthy dissertation.... summation... pressures bumping into 32 LBS is NOT A Problem.

2.   Lycoming is fully aware this condition exists...and if you INSIST on A SOLUTION ...YOU/I " WILL NOT BE SATISFIED" .

3.   I wish I could provide  you the Techs names and a summation of the 3 mans team's substantiations... for Lycoming's position!!!

FYI:   . Lycoming is HOLDING THEIR "COME TO WILLIAMSPORT"   pay for a seat ..for a week to learn ... April 4--8; 2022.

I agree there are other's who are flying with..and provided comments on this high oil pressure  and may  have shared a better solution than mine. 

Patrick,

Is that a Typo or are you really discussing high OilP?
 

Where the thread is discussing a quirky fuelP challenge…

Just wondering, not the thread police….

Best regards,

-a-

[PT20J]

They seem to have figured it out. I purchased a IO-360-A3B6 rebuilt from Lycoming in Oct 2018 and the fuel pressure is around 23 psi in cruise. The RSA injector has a max operating pressure of 80 psi.

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[Patrick Lyons]

Carusoam, 

We DO need a Man in BLUE like You, watching over the Mooney Spacers,  thank you !!

Yepper, my OIL PRESSURE gauge has been  bumping the red line since day one .  We checked my pressure with both a digital and analog Systems after new engine install.

Ottis Cameron , the JPI representative installed My JPI 830, in 2014. He urged me to include the optional OIL temp and Oil Pressure systems for the JPI 830.

  The original Mooney Oil gauge in the airplane worked fine ..  and the flags went up at install of the New Lycoming causing higher than prior oil pressure. 

That started the in-depth Conversations with Lycoming, Bendix and Mooney  .about the this engine assembly knowingly  exceeding oil pressure limits. 

Full Stop

Pat Lyons

Again:  Thank you for all your help and assistance with our forum.

[ArtVandelay]

They seem to have figured it out. I purchased a IO-360-A3B6 rebuilt from Lycoming in Oct 2018 and the fuel pressure is around 23 psi in cruise.

The high fuel pressure is a problem only at idle, at least it was in my case.

[larrynimmo]

I have documented my issue with fuel pressure years ago, and the problem hasn’t gone away, I have learned to live with it.my Lycomming factory engine was installed in sept 2018 .  Ever since I have had an issue with excessive fuel pressure developing after shutdown.

on occasion when I would stop somewhere and when I would go to use restroom and get ready to fly again…I physically could not move my mixture or my throttle lever…both would be fully out.   Left sitting there eventually the controls would work again.  Twice I had to send out the servo to get it rebuilt due to associated high pressure damage…rebuilder stated it appears it was exposed to pressures greater than 100#.

after getting second one on the plane…I let the plane get into this situation with my upper cowling removed and ready to check.  Controls were stuck…with two wrenches I cracked the fittings for the fuel pressure transducer…in less than 1/10th of a second all pressure bled off, and controls were no longer stuck.

I don’t know how to fix this, but I have learned to live with it…I literally bleed down my fuel pressure on shutdown as part of my procedure…not happy about doing this.  Lycomming and precision both want to point to an airframe issue.

[takair]

15 minutes ago, larrynimmo said:

I have documented my issue with fuel pressure years ago, and the problem hasn’t gone away, I have learned to live with it.my Lycomming factory engine was installed in sept 2018 .  Ever since I have had an issue with excessive fuel pressure developing after shutdown.

on occasion when I would stop somewhere and when I would go to use restroom and get ready to fly again…I physically could not move my mixture or my throttle lever…both would be fully out.   Left sitting there eventually the controls would work again.  Twice I had to send out the servo to get it rebuilt due to associated high pressure damage…rebuilder stated it appears it was exposed to pressures greater than 100#.

after getting second one on the plane…I let the plane get into this situation with my upper cowling removed and ready to check.  Controls were stuck…with two wrenches I cracked the fittings for the fuel pressure transducer…in less than 1/10th of a second all pressure bled off, and controls were no longer stuck.

I don’t know how to fix this, but I have learned to live with it…I literally bleed down my fuel pressure on shutdown as part of my procedure…not happy about doing this.  Lycomming and precision both want to point to an airframe issue.

That is very strange.  It seems that your idle cut off valve works better than most, but I would still expect the excess fuel pressure could backdrive the system.  It’s almost like you have a ball valve in the line.  You mentioned transducer, is it possible your fuel flow transducer has some FOD in it such that it allows flow to the engine but not back.  There has been at least one accident where a small amount of RtV got stuck in it…..in that case it wouldn’t allow flow to the engine.  The transducer has an intentional reduction to spin the impeller.  This would be an easy thing to check by removing the fittings.

[PT20J]

@larrynimmo do you have an RSA or Avstar fuel injection system? 

Some while back Lycoming switched fuel injection vendors from Precision Airmotive (RSA) to Avstar which is a copy of the RSA design. My engine, built in 2018, has the Avstar. The Avstar does seem to have a much tighter idle cutoff valve than the RSA which is designed to have a small leak to bleed off pressure. Precision has a spec on the leakage with a note that the valve is not designed as a fuel shutoff but only designed to reduce fuel flow enough to shut down the engine.

After shutdown, the heat in the engine compartment causes the fuel in the lines to boil and this vapor expands and increases the pressure. My fuel pressure increases after shutdown, but I haven’t had any issues with controls sticking. I’m not sure why that would happen, but the throttle is linked to the idle mixture valve so both throttle and mixture controls are exposed to unmetered fuel pressure.

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