Quote:
Originally Posted by Robert M. Gary
The fuel shop fixed my fuel servo by replacing the spring that holds
the fuel regulating diaphragm. The tech said the previous spring was
very stiff and he replaced it with one that was softer. Does that
indicate that the previous spring was broken (i.e. stiffer than it
should have been) or does Lycoming (Airmotive really) have a variety of
springs for adjustment purposes?? Did they fix the problem or just
adjust the fuel servo to work "post-problem".
-Robert, IO-360-A3B6
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I just got my 2001 Cessna 172SP with 350 hours on it back from annual and paid 2K for a fuel servo overhaul noted as fuel stain around the control arm connectors. My A&P at a busy high end facility called Lycoming for an explanation for the reason for a gummed up low time Servo and was told it was overpriming. I never prime over 3 sec which is POH.The only performance issue was some subtle power loss but this issue can cause engine failure/shutdown. I am going to call the overhaul facility for their rendition of this but it is a very under reported issue and hard to diagnose short of an annual.I do not know about the spring issue but these servos obviously have some insidious degradation problems.Since your life depends on it, I would have it overhauled and then watch this carefully and maybe have some one pull it or look up into the throttle body with a scope at each annual to be sure there is no recurring gum up since this cannot be seen from outside til late in the game.