FUEL SERVO REPLACED—EVERYTHING CHANGED

[Brian Scranton]

Dudes...my fuel servo hadn't been touched in 25 years. I had a burp on run up (with 12 inch flames coming out my exhaust), I had fluctuating fuel pressure in climbs, fuels smells when leaning...and was flying 140kts at 25/2500. 

So, I replaced it. No burp. No fluctuations. No more smell. AND HOLY SHIT, I make 153 KTAS now at 25.5/2450. I can't believe what a difference it makes when the engine in getting the right amount of fuel in a consistent way. 

[N9405V]

That’s awesome.


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[Dream to fly]

Be glad yours didn't fail the way mine did,  On final the engine just quits!  That will leave you with pucker factor.  The previous owner was playing A/P.  Took a few hours and this forum to figure out what the issues were.  Replaced it and have had no issues since. 

[neilpilot]

27 minutes ago, Dream to fly said:

Be glad yours didn't fail the way mine did,  On final the engine just quits!  That will leave you with pucker factor.  The previous owner was playing A/P.  Took a few hours and this forum to figure out what the issues were.  Replaced it and have had no issues since. 

Be glad your's didn't fail 8NM from the nearest airport.  https://www.ntsb.gov/about/employment/_layouts/ntsb.aviation/brief2.aspx?ev_id=20120721X23053&ntsbno=CEN12FA463&akey=1

 

[EricJ]

4 hours ago, Dream to fly said:

Be glad yours didn't fail the way mine did,  On final the engine just quits!  That will leave you with pucker factor.  The previous owner was playing A/P.  Took a few hours and this forum to figure out what the issues were.  Replaced it and have had no issues since. 

Mine went from cruise power to a backfiring, sputtery idle.   I was (extremely fortunately) within gliding distance of my destination airport, and on the ground it barely made enough power to taxi, still sputtering and backfiring.   I walked into the field A&Ps shop and he said, "Was that you?   Sounded like your fuel servo."

They verified the servo was bad and sent it off for rebuild.  When I picked it up I got a baggie full of the old o-rings and gaskets, and it was pretty clear that it had sat with water in it for some time during it's history.   No idea how long since it had been rebuilt or serviced, but, yeah, it was like a new airplane after that.   Starts really easy now, too.

[FloridaMan]

1 hour ago, Hyett6420 said:

What hell is a fuel servo, can someone post a photo?   I probably know it but not as a fuel servo.

signed

the dumb brit.

You brits probably have some weird name for it, but I always called it the "throttle body" until I knew the correct term. It's the thing that sits on the front of your intake with the butterfly valve on it that meters the fuel like Bosch K-Jetronic for cars. 

[RobertGary1]

I’m surprised you guys replaced them; any good fuel shop can rebuilt them. Mine would draw 48gal/hr in cruise and when I went to lean it it died. Pushed mixture back and landed trailing black smoke. Called Maxwell and asked who he used for rebuild and sent it to him. 

Worse part is just having to drop the lower cowl. 

-Robert

[Bob_Belville]

I had to exchange mine out last year.

The failure mode was that the engine was still getting fuel with mixture at idle cut off.  Once Lynn disconnected the mixture cable at the servo he could tell that the arm was not moving freely. Not field serviceable.

[RobertGary1]

1 hour ago, Bob_Belville said:

I had to exchange mine out last year.

The failure mode was that the engine was still getting fuel with mixture at idle cut off.  Once Lynn disconnected the mixture cable at the servo he could tell that the arm was not moving freely. Not field serviceable.

What did you end up paying for an exchange? I seem to recall that a full overhaul from the shop Maxwell recommended was only a few hundred bucks and that included servicing the spider and injectors (flow testing them). My labor and I mailed them the fuel components. Don't lose the injectors inserts, they're not easy to replace.

-Robert

[Brian Scranton]

2 hours ago, RobertGary1 said:

What did you end up paying for an exchange? I seem to recall that a full overhaul from the shop Maxwell recommended was only a few hundred bucks and that included servicing the spider and injectors (flow testing them). My labor and I mailed them the fuel components. Don't lose the injectors inserts, they're not easy to replace.

-Robert

For mine, the exchange was the same as a rebuild: Western Skyways charged me $1495

[RobertGary1]

19 minutes ago, Brian Scranton said:

For mine, the exchange was the same as a rebuild: Western Skyways charged me $1495

That sounds out of line. All they’re really doing is changing diaphragm, seals and flow testing.  I forget exactly what I paid but i don’t remember over $500  

-Robert

[Bob_Belville]

4 hours ago, RobertGary1 said:

What did you end up paying for an exchange? I seem to recall that a full overhaul from the shop Maxwell recommended was only a few hundred bucks and that included servicing the spider and injectors (flow testing them). My labor and I mailed them the fuel components. Don't lose the injectors inserts, they're not easy to replace.

-Robert

$1427.35 Triad Aviation. We did not mess with the spider or injectors.