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  #41  
Old 07-30-2013, 03:43 PM
bjohnson1234 bjohnson1234 is offline
 
Join Date: Oct 2012
Location: Scottsdale, AZ
Posts: 150
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I'm not sure what you mean by the "metered" fuel line. Do you mean it should be installed between the injection servo and the spider? Mine is installed after the boost pump before the gascolator. I'm going to be in Atlanta at least through the weekend, maybe I can stop up there.

Quote:
Originally Posted by Don at Airflow View Post
Yes, of course no weight on the crank doesn't help the hot idle problem either. But you have some installation issues to clean up yet. Remove the gascolator from the firewall, remove any pressure drops from the suction side side of the pumps. The flow meter should be in the metered fuel line.

If all that does not help then the last resort is to install smaller nozzle restrictors to raise the nozzle back pressure. This will not completely cure the problem but usually helps. We need to know the take off fuel flow and inlet fuel pressure to calculate the nozzle size that can be installed.

Don
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  #42  
Old 07-30-2013, 03:48 PM
bjohnson1234 bjohnson1234 is offline
 
Join Date: Oct 2012
Location: Scottsdale, AZ
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I'm not sure if they are champion or tempest, but since it has the LASAR system I'm guessing they're Tempest.

Quote:
Originally Posted by Flyingleap View Post
Bj, Just couldnt help but notice this comment on the Champion fine wire plugs.
I never liked them. They have a screw in the center of the plug where the connection (electrical) is made. Below it is a spring and a formed resistor. The resistance from the electrode end and that screw should be 1K ohms to maybe
2K Ohms, that s it. I have found a number of plugs that have 20K and greater resistance which gives you a "miss", but probably not like what you are seeing. What if many of these plugs have this high resistance, Hmmmm... High temperature, greater resistance. I only use Tempest now on my 180Hp Lyc and REM40E only. These have a sealed resistor which reads 1K no matter how many hours I put on them. Take a few plugs out and check, can't hurt.
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  #43  
Old 07-30-2013, 04:59 PM
Don at Airflow Don at Airflow is offline
 
Join Date: Jun 2006
Posts: 316
Default Check

No time or $ for OSH. I'll be in the shop, just give me a call if your flying over.
The flow meter should be in the metered fuel line, that is, between the fuel control and the flow divider.

Don
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  #44  
Old 08-04-2013, 03:27 PM
KCH130 KCH130 is offline
 
Join Date: Aug 2013
Location: Atlanta, GA
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This thread has caught my interest, plus I'm new to the forums.

I have a Mattituck XP-360 (IO-360B1A2), dual slick mags, C/S Hartzell 2-blade, Sam James plenum, Bendix RSA-5 fuel servo. I have a Mooney-style 90 degree butterfly valve that allows either filtered air or direct intake ram air. I've had the airplane 10 years and it has logged 400 hours since new; I was not the builder (2nd owner).

My engine performs great from takeoff to touchdown but experiences a similar RPM "hunting", 40-50 RPM on the ground, frequently on hot days. I've never worried that it would quit, but it sounds terrible and is embarrassing during a long, hot taxi in. Just like the previous poster, mixture & boost pump don't seem to affect the problem. My inflight CHTs stabilize between 330-380, oil temps 185-200 depending on season & OAT.

- I've had the fuel servo rebuilt - no change.
- I've sealed gaps around the plenum - no change.
- Tried fire sleeve on the injector lines - no change.
- Van's gascolator, which I am ready to remove.

Here is where my problem goes beyond erratic idle: My engine will not shut down with the mixture at I/CO on hot days once oil temps are above 210F. Increasing throttle doesn't seem to help much. At its worst, the engine may appear to stop and then spin several revolutions backwards before coming to a stop. I had just about decided to start over with a more traditional baffle system when I discovered this thread. The plenum seems to work great for X/C flying but is a nightmare for summertime ground ops.

I like the idea of a fuel pump blast tube, but my problems seem a bit more complex than the original poster. Suggestions welcome.

Ken
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  #45  
Old 08-04-2013, 06:33 PM
Mike S's Avatar
Mike S Mike S is offline
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Location: Dayton Airpark, NV A34
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Default Welcome to VAF!

Quote:
Originally Posted by KCH130 View Post
plus I'm new to the forums.

Ken
Ken, welcome aboard the good ship VAF
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VAF 909

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Flying as of 12/4/2010

Phase 1 done, 2/4/2011

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  #46  
Old 08-04-2013, 06:37 PM
bjohnson1234 bjohnson1234 is offline
 
Join Date: Oct 2012
Location: Scottsdale, AZ
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I'm headed to Spartanburg tomorrow to have Don take a look at mine. I'll let you know how it works out.

Quote:
Originally Posted by KCH130 View Post
This thread has caught my interest, plus I'm new to the forums.

I have a Mattituck XP-360 (IO-360B1A2), dual slick mags, C/S Hartzell 2-blade, Sam James plenum, Bendix RSA-5 fuel servo. I have a Mooney-style 90 degree butterfly valve that allows either filtered air or direct intake ram air. I've had the airplane 10 years and it has logged 400 hours since new; I was not the builder (2nd owner).

My engine performs great from takeoff to touchdown but experiences a similar RPM "hunting", 40-50 RPM on the ground, frequently on hot days. I've never worried that it would quit, but it sounds terrible and is embarrassing during a long, hot taxi in. Just like the previous poster, mixture & boost pump don't seem to affect the problem. My inflight CHTs stabilize between 330-380, oil temps 185-200 depending on season & OAT.

- I've had the fuel servo rebuilt - no change.
- I've sealed gaps around the plenum - no change.
- Tried fire sleeve on the injector lines - no change.
- Van's gascolator, which I am ready to remove.

Here is where my problem goes beyond erratic idle: My engine will not shut down with the mixture at I/CO on hot days once oil temps are above 210F. Increasing throttle doesn't seem to help much. At its worst, the engine may appear to stop and then spin several revolutions backwards before coming to a stop. I had just about decided to start over with a more traditional baffle system when I discovered this thread. The plenum seems to work great for X/C flying but is a nightmare for summertime ground ops.

I like the idea of a fuel pump blast tube, but my problems seem a bit more complex than the original poster. Suggestions welcome.

Ken
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  #47  
Old 08-04-2013, 07:06 PM
Don at Airflow Don at Airflow is offline
 
Join Date: Jun 2006
Posts: 316
Default Airflow Performance @ KSPA

After landing head west down the taxi way to the end. We're the last hanger. I'll have the gate open in the morning.

Don
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  #48  
Old 08-04-2013, 08:17 PM
jwyatt jwyatt is offline
 
Join Date: Feb 2006
Location: Goodhue, MN
Posts: 160
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Quote:
Originally Posted by bjohnson1234 View Post
I'm headed to Spartanburg tomorrow to have Don take a look at mine. I'll let you know how it works out.
Definitely keep us posted, I'm hoping to learn something vicariously! If I was based nearer to Don's shop, I likely would have hired him to take a look at it months ago.
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  #49  
Old 08-04-2013, 08:25 PM
KCH130 KCH130 is offline
 
Join Date: Aug 2013
Location: Atlanta, GA
Posts: 4
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If I find that it is not feasible to place a fuel filter in line prior to the electric boost pump, are there any specific recommendations on quality/durable fuel filters placed in the space about to be vacated by the gascolator?

Ken
RV-8
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  #50  
Old 08-04-2013, 11:20 PM
E. D. Eliot E. D. Eliot is offline
 
Join Date: Dec 2005
Location: San Pedro
Posts: 1,013
Default Maybe I missed it but

You did check the spark plugs AND high tension leads for too much resistance, right?
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