Cherokee 6 Fuel System Question

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WiPilot

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WiPilot
Looking for some input here; I have a Cherokee Six and after each flight I set the fuel selector to the "Off" position before putting it back in the hangar. When attempting to start the plane after it has sat awhile (1+ months) I'm assuming the fuel from the selector forward to the engine (?) has either evaporated/leaked out/magically disappeared via some other method, and the engine will struggle to stay running for a short time after startup even with the boost pump on. When regularly flying the airplane (think summer-time) this is not an issue.
So the question here is: how do I "prime" the line from the fuel selector to the injectors? It would seem as though the normal process of priming the engine for start by firing up the boost pump and waiting for fuel flow indication for a second or two on the fuel flow gauge is not sufficient to prevent a sputtering/stalling engine. I have tried to turn the fuel selector "on" to a tank with ample fuel while I do a 10-15 minute preflight (with mixture still at idle cutoff and throttle at idle), but that has not had any measurable effect. I'm hesitant to leave the boost pump on with mixture in full rich longer for fear of flooding the engine. I have tried to find schematics/more info regarding the fuel system on this airplane without much success. Is turning the fuel selector on with the mixture in cut off not really doing anything with regards to getting fuel into the line?

If it makes a difference, it is the 5 position selector; Off, Left Tip, Left Main, Right Main, Right Tip.

Also, if this is not posted in the correct place or this question is addressed elsewhere, please point me in the right direction!
 
I am trying to remember the procedure we used for the first start on the 6-300...

If I remember, it was pump on, mixture rich, throttle open for 10-15 seconds, then mixture off and start.

Not sure, but the secret was opening the throttle.

/HTH
 
Why do you turn the fuel selector to off?
 
Ah yes, I left that part out. Throttle is open 1/2" during priming and start.

IK04 said:
I am trying to remember the procedure we used for the first start on the 6-300...

If I remember, it was pump on, mixture rich, throttle open for 10-15 seconds, then mixture off and start.

Not sure, but the secret was opening the throttle.

/HTH
Click to expand...
 
I was told it was to prevent fuel from draining from the tips into the mains while sitting. It also seems like an extra safety measure and common sense to turn the fuel off while the airplane is parked...

Teeeeeechnically, this airplane is so old it doesn't have a POH but rather an AFM. Alas, technicalities aside, I can't find any reference to turning the fuel off while parked. Is the answer here really "don't turn the fuel selector to off"? What else is Off for besides in flight fires and other emergency related issues?

bradg33 said:
Why do you turn the fuel selector to off?
Click to expand...
 
I own 2 airplanes and I've been in a flying club with several airplanes, and worked for a flight school that had a bunch of airplanes. Parked airplanes virtually never had the fuel selector switched to "off" unless undergoing maintenance that dictated it be set to "off."
 
I e got a Cherokee 6 with the 4 tank set up. Welcome to the club.

I used to set the selector to off after every flight until a much wiser and experienced colleague suggested that it only adds an extra step in the preflight routine that if missed could be disastrous. So, now I leave it alone.

As to your other problem, it sounds like you are already priming correctly. I’m not sure this is a fuel issue. Get your mechanic to pull the fuel line and see if you’re getting fuel flow. If so,look at other things. Do a lean of peak mag check to really test the mags and plugs. Engine monitor? Data from that may show a problem with an exhaust valve.

Keep us updated. Will be curious to see the final answer.


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Is the hangar heated / do you preheat? That kinda just sounds like a really cold cold start.
 
Generally the practice is to not leave the selector in the both position if parked on a slant. Since your six is low wing I doubt it has that. You can leave it in any setting and the fuel will stay put.
 
drjcustis said:
As to your other problem, it sounds like you are already priming correctly. I’m not sure this is a fuel issue. Get your mechanic to pull the fuel line and see if you’re getting fuel flow. If so,look at other things. Do a lean of peak mag check to really test the mags and plugs. Engine monitor? Data from that may show a problem with an exhaust valve.
Click to expand...

Interestingly enough, the left mag was bad last summer (think 400+ rpm drop on the mag check) and was overhauled. I was told that's the mag that the engine starts on, and once replaced starting in general, especially hot starts, was a whole lot better. Before they found the mag to be the issue, all the spark plugs were replaced too, so I'm thinking spark isn't an issue, especially since this is only after it's sat for an extended time. I have a GEM Insights engine monitor, but the display on the stupid thing is fritzy and I don't trust it more than I can throw it. :(


Rgbeard said:
Injected or Carb'd?
Click to expand...

Injected - IO540-K1A5

AA5Bman said:
Is the hangar heated / do you preheat? That kinda just sounds like a really cold cold start.
Click to expand...

The hangar isn't heated, although it is insulated and stays measurably warmer than the outside air. I preheat for about 4 hours, but it's just a heat pad stuck to the oil pan, so not as good as a Tanis system or something like that. Of note, I really never fly when it's below 20F; it's usually around 30F or above before I can muster the courage to drag the thing out and horse around with it on a cold icy ramp.
 
WiPilot said:
Injected - IO540-K1A5
Click to expand...

Basically same engine as was in my Lance.

FUEL - ON

MIXTURE - FULL

THROTTLE - OPEN 1/2"

FUEL PUMP - ON (UNTIL 10 GPH REACHED ON FUEL FLOW)

MIXTURE - CUTOFF

STARTER - ENGAGE

MIXTURE - BRING FORWARD ONCE ENGINE STARTS (SET ACCORDINGLY)

Used this procedure the entire time I owned the plane, started every single time. I believe this is how it's outlined in the Lycoming IO-540 operators manual as well. Let me see if I can find it.

EDIT: Operator's manual here...check page 3-2: https://www.lycoming.com/sites/default/files/O & IO-540 Oper Manual 60297-10.pdf
 
BGF_Yankee said:
Basically same engine as was in my Lance.

FUEL - ON

MIXTURE - FULL

THROTTLE - OPEN 1/2"

FUEL PUMP - ON (UNTIL 10 GPH REACHED ON FUEL FLOW)

MIXTURE - CUTOFF

STARTER - ENGAGE

MIXTURE - BRING FORWARD ONCE ENGINE STARTS (SET ACCORDINGLY)

Used this procedure the entire time I owned the plane, started every single time. I believe this is how it's outlined in the Lycoming IO-540 operators manual as well. Let me see if I can find it.

EDIT: Operator's manual here...check page 3-2: https://www.lycoming.com/sites/default/files/O & IO-540 Oper Manual 60297-10.pdf
Click to expand...


Yep. That's it. Worked every time for me (unless something else was wrong).
 
BGF_Yankee said:
Basically same engine as was in my Lance.

FUEL - ON

MIXTURE - FULL

THROTTLE - OPEN 1/2"

FUEL PUMP - ON (UNTIL 10 GPH REACHED ON FUEL FLOW)

MIXTURE - CUTOFF

STARTER - ENGAGE

MIXTURE - BRING FORWARD ONCE ENGINE STARTS (SET ACCORDINGLY)

Used this procedure the entire time I owned the plane, started every single time. I believe this is how it's outlined in the Lycoming IO-540 operators manual as well. Let me see if I can find it.

EDIT: Operator's manual here...check page 3-2: https://www.lycoming.com/sites/default/files/O & IO-540 Oper Manual 60297-10.pdf
Click to expand...

I have the IO540K1A5. This procedure works for me on cold starts. I will note that in the beginning while priming with the fuel pump on I sometimes did not open the throttle enough even though I thought I did. Now while priming I am sure to open it quite a bit and then close to 1/2" before cranking. It really seems to like that a lot and fires up right away.
 
WiPilot said:
The hangar isn't heated, although it is insulated and stays measurably warmer than the outside air. I preheat for about 4 hours, but it's just a heat pad stuck to the oil pan, so not as good as a Tanis system or something like that. Of note, I really never fly when it's below 20F; it's usually around 30F or above before I can muster the courage to drag the thing out and horse around with it on a cold icy ramp.
Click to expand...

I'm still pretty suspicious this is just a run-of-the-mill cold temperature start. Does this happen in the summer? Those oil pan heaters don't do much in terms of heating the engine especially if they're only turned on for four hours. I recently had one on my plane and if I left it on for more like 16 hours it seemed to help a bit, but if I either only left it on a little while or started without using it, I'd get a start just like the one you described. Similar outside temperatures and a kind of lopey, coughy, sputtery start for 10-15 seconds and then normal. It's like the sound of engine damage... ugh. :shudder: Don't underestimate how cold soaked an engine can get, even when it doesn't feel that cold.

Since then I've installed a top of the line Reiff system with the cylinder bands and everything. This system absolutely nukes the engine in just an hour or so. If I stick my hand in the cowl It's really warm and the start is almost like a hot start, but once it's going it's perfect, even if it's 10 degrees outside.

PS - in re-reading your original post you said this actually doesn't happen in summer as I suspected, but you attributed this to the fact that you were flying more. I'm pretty sure it's just because it's not as cold overnight in the summer.
 
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