Fuel servo replacement

[xcrmckenna]

On my 77’ J I’m only getting about 14.5 gph full throttle on takeoff at sea level. We are planning to send off my fuel servo and divider off to be adjusted or overhauled. Has anyone had any work done by Western Skyways?

 

 

Sent from my iPhone using Tapatalk

[larrynimmo]

I dealt with AVStar direct in Jupiter fl...they turn around quickly...while it looks perfect, I’ve had repeat issues with excessive pressure buildup...

I am to the point that I bleed down the pressure by opening mixture after shutdown 

[jetdriven]

1 hour ago, xcrmckenna said:

 

On my 77’ J I’m only getting about 14.5 gph full throttle on takeoff at sea level. We are planning to send off my fuel servo and divider off to be adjusted or overhauled. Has anyone had any work done by Western Skyways?

 

 

Sent from my iPhone using Tapatalk

 

they liklely send it off to a fuel system repair shop and mark it up 50%.  just send it to a shop that can overhaul it.

[xcrmckenna]

they liklely send it off to a fuel system repair shop and mark it up 50%.  just send it to a shop that can overhaul it.

My understanding western skyways does overhaul them in house. Is that not correct?


Sent from my iPhone using Tapatalk

[xcrmckenna]

I dealt with AVStar direct in Jupiter fl...they turn around quickly...while it looks perfect, I’ve had repeat issues with excessive pressure buildup...
I am to the point that I bleed down the pressure by opening mixture after shutdown 

I spoke with a Mooney owner today that just got a servo and diverter from them. They had everything in the shelf for fast turn around. I’ll give them a call after Christmas. Thanks for the endorsement. Was that your problem that got you to overhaul your servo or are you still having to do that?


Sent from my iPhone using Tapatalk

[Guest]

The OEM supplier, Precision Airmotive isn’t really expensive and sells through a number of networks.

Clarence

[xcrmckenna]

The OEM supplier, Precision Airmotive isn’t really expensive and sells through a number of networks.
Clarence

Nice, they are just north of me.


Sent from my iPhone using Tapatalk

[PT20J]

Are you sure that the servo is bad? Assuming that the engine is putting out rated power, I would expect a FF that low to cause elevated head temperatures. I'd verify the accuracy of the FF indicator. Transducers can read low as they age.

Also, I'd contact Al Jesmer at Precision Airmotive (now part of Tempest) and discuss it with him. I've found him very helpful. alan@tempestaero.com

Skip

[Guest]

Just now, xcrmckenna said:

Nice, they are just north of me.


Sent from my iPhone using Tapatalk

I thought that they were in your part of the country.  They may also do test and repair for you.

Clarence

[EricJ]

1 hour ago, xcrmckenna said:

My understanding western skyways does overhaul them in house. Is that not correct?


Sent from my iPhone using Tapatalk

They say they do, iirc.

They overhauled my flow divider several years ago.   I think it was several hundred bucks, which seems high in retrospect since there's almost nothing to those things.   We sent it in because we noticed a tear in the diaphragm when we opened it up to check for dirt, etc.   My IA recommended them, so off it went.   'Spensive, but it's been fine since.

When my servo failed it got sent to the local engine shop, which is a repair station for those.   It's been fine since, too.

 

[xcrmckenna]

Are you sure that the servo is bad? Assuming that the engine is putting out rated power, I would expect a FF that low to cause elevated head temperatures. I'd verify the accuracy of the FF indicator. Transducers can read low as they age.
Also, I'd contact Al Jesmer at Precision Airmotive (now part of Tempest) and discuss it with him. I've found him very helpful. alan@tempestaero.com
Skip

My EGT’s are high on take off when I’m that low. I don’t spend much time that low as the higher I go the fuel flow is sufficient. I verify my fuel flow down to the .1 so my fuel flow indication is correct.


Sent from my iPhone using Tapatalk

[xcrmckenna]

I thought that they were in your part of the country.  They may also do test and repair for you.
Clarence

Would you suggest anything else? My egt’s are high on take off, my fuel flow indication is within a .1, and I’m full throttle and full mixture. We verified the throttle and mixture are hitting the stops. Or is the fuel servo a good culprit?


Sent from my iPhone using Tapatalk

[EricJ]

14 minutes ago, xcrmckenna said:

Would you suggest anything else? My egt’s are high on take off, my fuel flow indication is within a .1, and I’m full throttle and full mixture. We verified the throttle and mixture are hitting the stops. Or is the fuel servo a good culprit?
 

How's the fuel pressure?   Does it matter whether the boost pump is on or not?

I'd check all of the filters/screens, too, including the finger filter at the servo.

The flow divider does almost nothing, actually.   It's just a chamber with an inlet and four outlets, for the most part.   There's a diaphragm that just plops down when there's no inlet pressure to cut off flow to the outlets when you turn the engine off.   Unless it's dirty inside, which is easy to inspect and fix, or there's a problem with the diaphragm, there's not much reason to suspect it is creating a problem from my understanding of your description.

There's a trick using a piece of clear tubing to replace the fuel line from the servo to the divider in order to make sure there's no air getting into the fuel flow, i.e., look for bubbles.

Might be worth trying a few things before sending in the servo if you haven't already.

 

 

Edited December 24, 2020 by EricJ

[xcrmckenna]

How's the fuel pressure?   Does it matter whether the boost pump is on or not?
I'd check all of the filters/screens, too, including the finger filter at the servo.
The flow divider does almost nothing, actually.   It's just a chamber with an inlet and four outlets, for the most part.   There's a diaphragm that just plops down when there's no inlet pressure to cut off flow to the outlets when you turn the engine off.   Unless it's dirty inside, which is easy to inspect and fix, or there's a problem with the diaphragm, there's not much reason to suspect it is creating a problem from my understanding of your description.
There's a trick using a piece of clear tubing to replace the fuel line from the servo to the divider in order to make sure there's no air getting into the fuel flow, i.e., look for bubbles.
Might be worth trying a few things before sending in the servo if you haven't already.
 
 

The fuel pressure seems to be within limits. About 27psi with the boost pump on and 18-20 with it off. We are leaning more towards the fuel servo more than the diverter but we are still in the trouble shooting stage for sure. It has been an on going problem but when I fly out of a high elevation airport and normally fly at a high elevation I have enough fuel flow to keep the temps at normal operations for 99% of my flights. I just pull the throttle back when I’m in low cruise.

I will run the clear tube inspection by my mechanic. Thanks.


Sent from my iPhone using Tapatalk

[PT20J]

1 hour ago, EricJ said:

They overhauled my flow divider several years ago.   I think it was several hundred bucks, which seems high in retrospect since there's almost nothing to those things.

Kind of late now, but IIRC Precision says the flow divider is field serviceable. As you said, there’s not much to it.

[EricJ]

6 minutes ago, PT20J said:

Kind of late now, but IIRC Precision says the flow divider is field serviceable. As you said, there’s not much to it.

I think that's correct.   At the time my IA wanted to send it in, so it got sent in. 

 

[PT20J]

5 minutes ago, EricJ said:

I think that's correct.   At the time my IA wanted to send it in, so it got sent in. 

 

I hear you. Sometimes you just got to go with the flow 

[RobertGary1]

16 hours ago, M20Doc said:

The OEM supplier, Precision Airmotive isn’t really expensive and sells through a number of networks.

Clarence

Any reason to actually replace one vs sending to a fuel shop?

[RobertGary1]

13 hours ago, PT20J said:

Kind of late now, but IIRC Precision says the flow divider is field serviceable. As you said, there’s not much to it.

You’d think but I did have an engine failure after service. The shop I sent it to decided they could save me money and knew the issue rather than a full overhaul. Engine started pulling 30 gal/hr on climb out and when I pulled the mixture back went stone dead. Ended up calling Maxwell and getting a recommendation for a different fuel shop. I as fine for 500 hrs then until I threw a rod and just bought a new power plant from Lycoming. 

[Guest]

3 hours ago, RobertGary1 said:

Any reason to actually replace one vs sending to a fuel shop?

It’s just another option, and would likely be available overnight with no down time, plus getting the assurance of a factory overhaul, just like buying an engine from Lycoming.  
 

Clarence

[carusoam]

Mags and fuel systems are kinda high tech...

The kinda tech that requires knowledgable people to OH properly... not just follow the manual...

With mags, you have an independent pair... fuel, you get one...

PP logic only...

Best regards,

-a-

[Yetti]

Texas Carburetors in Justin Texas did mine.   Wanted the Servo, flow divider and Injectors to flow test.   Cost was about the cost of a new servo, but I got the divider OHed and replaced 2 Injectors and the other 2 OHed.   I liked the idea of the whole system being done as a system

[xcrmckenna]

Got a dumb question. I started sending emails out to the shops for availability ans prices and I thought telling them it was a 1977 Mooney M20 J Lycoming IO-360 A3B6D. But they need a part number for the fuel servo. So I looked at my parts manual and all it says is injector, fuel, Lycoming.
 

Where would I find the P/N? Do I need to find a Lycoming application list? I went through my logs and they don’t list it by a parts number either. Or just remove the cowl and find it that way? 
 

[adverseyaw]

My '78 has an RSA-5AD1, p/n 2524054-11. Here's a photo of the part and the location of the ID plate. Not sure if yours is the same (although wouldn't you have an -A1B6D...?)

When I had to have mine overhauled a few years back, Precision said they wouldn't do it (they were focused on manufacturing) and directed me to a few places, I chose D&G Supply. They did my flow divider, too. Total was around $400 with $100 in freight.

[PT20J]

It’s considered part of the engine, so it would be in the Lycoming engine IPC.