REFLECTOR: Engine backfiring

Wed Aug 16 11:11:42 CDT 2006

If operating correctly you will feel small puffs. But the check valve will 
not allow suction between the puffs.

Andy

----- Original Message ----- 
From: "Laurence Coen" <lwcoen at hotmail.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Wednesday, August 16, 2006 11:03 AM
Subject: Re: REFLECTOR: Engine backfiring

> To: Riffle,sniffle and whiffle
>
> Sniffle has to do with inhaling , not exhaling. I don't know what riffle
> means unless you'r shuffeling cards .  Whiffle is a real word that means
> blowing in puffs which would fit its function.
>
> Larry Coen
> N135LC
>
> ----- Original Message ----- 
> From: "John Tvedte" <JohnT at comp-sol.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Wednesday, August 16, 2006 10:11 AM
> Subject: Re: REFLECTOR: Engine backfiring
>
>
>> Ok - I thought it was called a sniffle valve?
>>
>> John
>>
>> -----Original Message----- 
>> From: reflector-bounces at tvbf.org on behalf of Scott Derrick
>> Sent: Wed 8/16/2006 9:42 AM
>> To: Velocity Aircraft Owners and Builders list
>> Cc:
>> Subject: Re: REFLECTOR: Engine backfiring
>>
>>
>> I thought it was called a whiffle valve?
>>
>> Dave Dent wrote:
>>
>> Your right I have seen this before.  Some call it the riffle valve.
>> Manifold
>> drain valve.  I have encountered this valve missing and one time causing 
>> a
>> fire.  The fuel didn't drain out and it back fired and lit off.
>> Good Call Andy
>> Dave
>> ----- Original Message ----- 
>> From: "Andrew Ellzey" <ajlz72756 at yahoo.com> <mailto:ajlz72756 at yahoo.com>
>> To: <velocity at davebiz.com> <mailto:velocity at davebiz.com> ; "Velocity
>> Aircraft Owners and Builders list"
>> <reflector at tvbf.org> <mailto:reflector at tvbf.org>
>> Sent: Tuesday, August 15, 2006 9:44 PM
>> Subject: Re: REFLECTOR: Engine backfiring
>>
>>
>>
>>
>> Dave,
>>
>> I had a Mooney M20E that had this engine and flew it for 15 years and
>> about
>> 600 hours. This engine is known for this problem. The first thing I would
>> look at is; there is a 45 degree AN fitting on the bottom of your engine
>> that is supposed to be your airbox drain. This 45 degree fitting is
>> supposed
>> to have a check valve internal to this fitting. You would never know it 
>> is
>> installed unless you know that it is there. This is the problem, most
>> people
>> think it is a standard AN fitting and will install a new fitting without
>> the
>> check valve at overhaul. With the check valve missing your engine sees
>> this
>> as an air induction leak and will idle rough and make the backfiring
>> worse.
>> A easy way to tell if your valve is working properly is to put your 
>> finger
>> over the drain line with the engine running and see if you engine lowers
>> its
>> idle speed. I have also seen these check valves stuck open and just needs
>> cleaning. I tried to order a new check valve when I found that mine had
>> been
>> changed out to a standard fitting after fighting this problem for 8 
>> years.
>> I
>> never could get a good part number to order one and had to make my own. 
>> If
>> yours is missing or gone bad I can tell you how to make one. Or you can
>> install a PVC valve inline with your drain and it will work just as well.
>> The PVC valve should close as your engine sucks air out of your airbox.
>> This
>> valve was supposed to drain the excess fuel that drains out of you
>> injectors
>> and into your airbox when you shut down your engine and suck closed when
>> you
>> start your engine.
>>
>> Andy Ellzey
>>
>>
>> ----- Original Message ----- 
>> From: "Dave Philipsen" <velocity at davebiz.com>
>> <mailto:velocity at davebiz.com>
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> <mailto:reflector at tvbf.org>
>> Sent: Tuesday, August 15, 2006 10:38 PM
>> Subject: REFLECTOR: Engine backfiring
>>
>>
>>
>>
>> Here's a question perhaps for some of the engine experts:  I've got a
>> STD FG with IO360-A1A engine.
>> It has one standard magneto and one Jeff Rose electronic ignition.  The
>> engine and oil cooling are not a
>> problem even with OATs in the low 90s. But, I have a problem (it's not a
>> huge problem) with backfiring
>> during taxi *after* I land.  Taxiing before takeoff seems to be ok.  The
>> backfiring happens maybe once
>> every 30 seconds or so.  The engine also seems to run a little rough at
>> this time.  I've tried running lean,
>> running rich, running on just the magneto, running on just the
>> electronic ignition.  None of these seems to
>> prevent the backfiring during taxi.  The engine never seems to have
>> problems before or during takeoff or
>> during cruise or descent...just taxiing back after landing.
>>
>> I'm starting to think it's a vapor lock problem or something since the
>> fuel flow is way down and the fuel is
>> sitting in the lines longer and heating up.  I had the cowling off the
>> other day and was checking the routing
>> of the fuel injector lines and they don't appear to be routed near the
>> exhaust manifolds or anything like that.
>> I was thinking of maybe experimenting with some insulating material
>> around the individual injector lines as
>> well as the main fuel line.  Any ideas?
>>
>> -- 
>> Dave Philipsen
>> STDFG
>> N171SP
>>
>>
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>>
>>
>> -- 
>>
>> -
>>     The most effectual engines for [pacifying a nation] are the public
>> papers... [A despotic] government always [keeps] a kind of standing army
>> of newswriters who, without any regard to truth or to what should be like
>> truth, [invent] and put into the papers whatever might serve the
>> ministers.
>>
>>     Thomas Jefferson to G. K. van Hogendorp
>>     Oct. 13, 1785. (*) ME 5:181, Papers 8:632
>>
>>
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