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Primer plunger?

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Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Wed Jan 18, 2017 10:29 am Post subject: Primer plunger?

Was planning to add this primer to the FSII, specifically this item in the photo - it is new old stock. Tested it and while it sucks fuel into the intake side, when you push the plunger in, it also squirts it back out the same line, unless you do it quick and hard, in which case it squirts it out both lines.

I am thinking it is no good, but never having used one, what do I know? Is that the way it is supposed to work? 

http://www.aircraftspruce.com/catalog/appages/primerplung.php?clickkey=69864

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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

ceengland7(at)gmail.com
Guest

Posted: Wed Jan 18, 2017 10:55 am Post subject: Primer plunger?

On 1/18/2017 12:29 PM, Richard Pike wrote:

 	  Quote: 	
		   



 Was planning to add this primer to the FSII, specifically this item in the photo - it is new old stock. Tested it and while it sucks fuel into the intake side, when you push the plunger in, it also squirts it back out the same line, unless you do it quick and hard, in which case it squirts it out both lines.

 I am thinking it is no good, but never having used one, what do I know? Is that the way it is supposed to work?



 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kingsport, TN 3TN0

I've never used that model, but they're just piston pumps, with inlet & 
	


outlet check valves. Sounds like the inlet check  valve is stuck open. 

Can you disassemble to check it?



Charlie

George Alexander

Joined: 10 Jan 2006
Posts: 245
Location: SW Florida

Posted: Wed Jan 18, 2017 11:00 am Post subject: Re: Primer plunger?

 	  Richard Pike wrote: 	
		  

.  S  N  I  P  >

I am thinking it is no good, but never having used one, what do I know? Is that the way it is supposed to work? 

http://www.aircraftspruce.com/catalog/appages/primerplung.php?clickkey=69864 	




Richard

Definitely not the way it is supposed to work.  One side in... the other out.  These are notorious for going bad, generally from drying out due to lack of use.  However, I still use them to fill the bowls  instead of the bulb pump.  



If this one has been sitting for a while, trying to get it to work will soak the insides with fuel.  Letting it sit for a day or two may lube the internal parts enough to get it to work.  

When I get a replacement, I always make sure I have a spare on hand.

Worth what you paid for it... your experience may vary.

_________________
George Alexander
FS II R503
E-LSA N709FS
http://www.oh2fly.net

stuart(at)harnerfarm.net
Guest

Posted: Wed Jan 18, 2017 11:25 am Post subject: Primer plunger?

That looks pretty much like the one on my Firefly.



Concur with a stuck check valve.



Always check the simple and easy stuff first. Are you are the fuel supply is

connected to the proper fitting? Might be worth reversing the hoses at the

primer just to see what happens.



If you can't get it apart perhaps soaking in your favorite gasoline additive

(Sea Foam, Marvel Mystery Oil, etc.) might free it up. 100LL makes a pretty

good solvent for fuel system stuff.



If this is a used primer assy. there is a good chance that the check valve

is gummed up with varnish and it may take something more like Toluene or MEK

to break it free. If all the internal parts are metal it should cause no

harm. All bets off for seals and plastic parts though, so use at your own

risk. 



If new, perhaps a visit with the vendor will get it replaced.



Let us know what you find out.



Stuart



--

byoungplumbing(at)gmail.c
Guest

Posted: Wed Jan 18, 2017 11:51 am Post subject: Primer plunger?

Never found a need for a primer on my 912.    Pull the throttle all the way back,. Pull the enrichener on,.  Crank 3 or 4 blades, let it rest 5 sec. Then crank it again.   Fires right up. 

Boyd young

George Alexander

Joined: 10 Jan 2006
Posts: 245
Location: SW Florida

Posted: Wed Jan 18, 2017 2:58 pm Post subject: WLA

 	  George Alexander wrote: 	
		   	  Richard Pike wrote: 	
		  

.  S  N  I  P  >

I am thinking it is no good, but never having used one, what do I know? Is that the way it is supposed to work? 

http://www.aircraftspruce.com/catalog/appages/primerplung.php?clickkey=69864 	




Richard

Definitely not the way it is supposed to work.  One side in... the other out.  These are notorious for going bad, generally from drying out due to lack of use. (IGNORE THAT FILLING THE BOWLS remark. Primer don't do that.)



If this one has been sitting for a while, trying to get it to work will soak the insides with fuel.  Letting it sit for a day or two may lube the internal parts enough to get it to work.  

When I get a replacement, I always make sure I have a spare on hand.

Worth what you paid for it... your experience may vary.

_________________
George Alexander
FS II R503
E-LSA N709FS
http://www.oh2fly.net

Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Wed Jan 18, 2017 3:37 pm Post subject: Re: Primer plunger?

Like I said, this primer/plunger is brand new, never been used, sitting on the shelf for ... hmmm...  probably since my MKIII was running a 532...



OK, since it may not be worth a flip anyway, will attempt to open this primer/plunger up using Large Mechanical Devices and see what the insides look like. Earlier today I dumped some Marvel Mystery Oil down the intake side and it didn't do any good, nothing changed. 



In an attempt to loosen the check valve (if any) I took it and beat it against the side of the wooden picnic table. No change, but the wife did ask me if we had any ducks in the back yard. Not helpful.



The only reason I am fooling with it is because the FSII with a 582 is driving us crazy - it belongs to my buddy, who has the hangar next to me, and it is drawing the fuel out through the top of the tanks, with the fuel pickups weighted, and laying in the bottoms of the tanks. Same as we did with our Hummers & Drifters years ago. No Big Deal.



After the two lines come out of the top of the 2 tanks, they join, then go downhill to the primer squeeze bulb (new) then further downhill to the filter, then the gascolator (to sump out any water) and then to the Facet pump. And then uphill to the Mikuni pulse pump next to the engine, and then to the 2 carburetors.



Sounds simple, right? Yeah, bet me and lose! 



Drag the airplane out of the hangar, tanks are almost full, turn on the Facet pump, squeeze the bulb several times, it gets as hard as a rock, you can hear the Facet load up, just as they always change sound when the float bowl gets full and the float needle cuts off, because the floats are full. Sounds ready.



Now you turn on the mags, hit the starter, and grind it over ad infoonity - nothing happens.



Grab the spray can of primer/starter and shoot a dose into the air filter, ....   and it starts.



If you pull a float bowl off during this fiasco, it is dry. In spite of our best efforts, we cannot get any fuel up into the float bowls when the engine is not running. 



But once you get the engine to semi- sorta - primer spray - run, it sucks the fuel right on up and then functions flawlessly for the next week. But let it sit for a month? HAH! 



I am not willing to fool with this thing endlessly, I have already spent hours redoing the fuel lines and connections, and it changes nothing. If I can rig a primer to shoot some gas into the carbs and get it to simulate running, so that then it will take over and behave normally, and everyone will be happy - good. 



So that is why I am trying to get this primer system to work. Or am I missing something? All suggestions will be pondered.

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jan 18, 2017 4:12 pm Post subject: Primer plunger?

Richard/Kolbers:



I would never fly an aircraft that was not operating normally.



Trying to get around a stubborn engine may not be a good solution.



Should be able to pump the float bowls full, pull primer all the way on,

throttle closed, hit starter and fire right up.  If not, find out why and

fix it before committing to flight.  Ain't worth the risk of losing an

engine and getting hurt.



Based on your airstrip, wouldn't want to get caught short.



Concerned friend.



john h

mkIII

Titus, Alabama



--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

ceengland7(at)gmail.com
Guest

Posted: Wed Jan 18, 2017 4:49 pm Post subject: Primer plunger?

On 1/18/2017 5:37 PM, Richard Pike wrote:

 	  Quote: 	
		   



 Like I said, this primer/plunger is brand new, never been used, sitting on the shelf for ... hmmm...  probably since my MKIII was running a 532...



 OK, since it may not be worth a flip anyway, will attempt to open this primer/plunger up using Large Mechanical Devices and see what the insides look like. Earlier today I dumped some Marvel Mystery Oil down the intake side and it didn't do any good, nothing changed.



 In an attempt to loosen the check valve (if any) I took it and beat it against the side of the wooden picnic table. No change, but the wife did ask me if we had any ducks in the back yard. Not helpful.



 The only reason I am fooling with it is because the FSII with a 582 is driving us crazy - it belongs to my buddy, who has the hangar next to me, and it is drawing the fuel out through the top of the tanks, with the fuel pickup weighted, and laying in the bottom of the tanks. Same as we did with our Hummers & Drifters years ago. No Big Deal.



 After the two lines come out of the top of the 2 tanks, they join, then go downhill to the primer squeeze bulb (new) then further downhill to the filter, then the gascolator (to sump out any water) and then to the Facet pump. And then uphill to the Mikuni pulse pump next to the engine, and then to the 2 carburetors.



 Sounds simple, right? Yeah, bet me and lose!



 Drag the airplane out of the hangar, tanks are almost full, turn on the Facet pump, squeeze the bulb several times, it gets as hard as a rock, you can hear the Facet load up, just as they always change sound when the float bowl gets full and the float needle cuts off, because the floats are full. Sounds ready.



 Now you turn on the mags, hit the starter, and grind it over ad infoonity - nothing happens.



 Grab the spray can of primer/starter and shoot a dose into the air filter, ....   and it starts.



 If you pull a float bowl off during this fiasco, it is dry. In spite of our best efforts, we cannot get any fuel up into the float bowls when the engine is not running.



 But once you get the engine to semi- sorta - primer spray - run, it sucks the fuel right on up and then functions flawlessly for the next week. But let it sit for a month? HAH!



 I am not willing to fool with this thing endlessly, I have already spent hours redoing the fuel lines and connections, and it changes nothing. If I can rig a primer to shoot some gas into the carbs and get it to simulate running, so that then it will take over and behave normally, and everyone will be happy - good.



 So that is why I am trying to get this primer system to work. Or am I missing something? All suggestions will be pondered.



 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kingsport, TN 3TN0

This is coming from a 4stroke background, so season as desired.
	




If carb float bowls aren't filling and you're confident that the bulb is 

functioning normally, then it sounds like either the check valve in the 

pulse pump is sticking (is that likely?), or both carb float valves are 

sticking (again, likely?) Either way, once the motor starts shaking, the 

vibration is almost certainly freeing up whatever is sticking, which 

would explain it running after the 'artificial' prime.



For troubleshooting, if it were my 4 stroke engine, I'd 1st plumb around 

the pulse pump and run the facet, then see if you get normal startup. (I 

spent several different lives troubleshooting various systems, and if 

you do it for money, you do the easy first). If no, don't use your 

primer can. Pull the float bowls (which we can assume will still be 

dry), and try the Facet again. Fair chance that the action of removing 

the bowls will jar the float valves loose, but if it doesn't, then 

you'll know for sure that your problem is there.



I'd have to agree with John; flying it like that does sound a bit 

spooky. What if whatever is sticking decides that the vibration isn't 

enough to keep it freed up?



Charlie

There are 10 kinds of people in this world: those that understand binary 

and those that don't.

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jan 18, 2017 5:08 pm Post subject: Primer plunger?

After reading this again and Charlie's suggestions, pull the fuel lines at

the carbs, turn on the Facet, and see if fuel getting that far.  Guess you

have probably done that.



Change one thing at a time until the monster appears.



john h

mkIII

Titus, Alabama





--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Wed Jan 18, 2017 5:31 pm Post subject: Re: Primer plunger?

Thanks John & Charlie.

After it starts, Ed usually lets it sit at a fast idle for around 5 minutes to let it slowly warm up to fully warm, and then no matter where we go for the rest of the day or how many times it is restarted, it behaves itself normally for the rest of the day. 



It is only after it sits for a month that we have to jump through these hoops. And since Ed is still working & gainfully employed, he some times doesn't get to fly for a month or so.



If I understand correctly, you are saying it is acceptable to run a bypass around the Mikuni pulse pump and straight to the carbs.  So - now we have a fuel line coming up from below the tanks (where the Facet electric pump lives) and as it gets to the Mikuni pulse pump, I split the line and then join it again upstream of the Mikuni pulse pump. And then T it off to each of the 2 carbs.



Now both the carbs are being fed by the Facet prior to start up - and then both the Mikuni and the Facet after startup? (Unless the float needles are sticking in the float needle seats prior to startup, and then nothing gets fed) (I will check this tomorrow by tapping on the floats while the Facet is running and seeing if anything changes/the float bowls fill up)



Assuming that bypassing the Mikuni and letting the Facet apply pressure directly to the float needle assembly's, - which then respond properly - and that this resolves the problem - then the problem would be that until the Mikuni starts to pump because the engine is starting to run, that when the engine is not running then the Mikuni is not letting fuel flow freely through it. Correct? 

Which then begs the question - is that normal for a Mikuni? Should a Mikuni allow fuel to flow through it when there is pressure on the inlet side of the pump, but no pulses being received through the pulse port? I am thinking that a normal Mikuni ought to allow the fuel to flow through it. Comments?

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

stuart(at)harnerfarm.net
Guest

Posted: Wed Jan 18, 2017 5:31 pm Post subject: Primer plunger?

Richard,



Are you able to see the fuel through the lines?



Serenity is basically the same setup, minus the Facet pump and the sump.

When I use the squeeze bulb I can watch the fuel flow up through the Mikuni

pulse pump and filter then go to the carb. If I am gentle and careful I can

usually tell when the floats shut off the flow and the bowl is full.



Just a guess here based on your description, but it sounds like the Facet

isn't generating enough pressure to push the fuel through the Mikuni and

fuel flow is stopped there. I can't say if this is the fault of the Mikuni

or the Facet.



A couple of things to try: Bypass the pumps one at a time and see if you can

isolate the symptom. If you use clear hose it my help figure it out. You

wouldn't have to fly, just drain the lines and bowls and see what happens.

The symptom sounds like vapor lock even thought that is not it.



Oh, one more thought. Pull a hose from one of the carbs and see if you can

get gas to come out with just the Facet or the squeeze bulb.



Once the engine is running, how does it perform if you turn off the Facet

pump?



More troubleshooting would probably involve splicing in a pressure gauge in

various places to see that is going on. 



For what it is worth, I like using the squeeze bulb to get gas up to the

bowl then a couple of squirts from the primer (cold engine only) usually

gets the 447 to fire off on the first pull of the rope.



Hope this helps,



Stuart

--

Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Wed Jan 18, 2017 5:54 pm Post subject: Re: Primer plunger?

Good stuff Stuart, thanks. One of the run-up checks is to turn off the Facet and wait a bit to see if the engine runs on just the pulse pump. It has always worked OK.



Currently using NAPA black fuel injection fuel line, but can pull it off to do some testing, and that is what we will do tomorrow. Weather is supposed to be good, so we will disconnect and re-plumb to see what works and what doesn't before we ever actually fire it up. 



My bud who is helping me with the Firefly build is coming over to help, and that is good. The older I get, the less I am impressed with how good I am at sorting this kind of stuff out.



Will post tomorrow night and let you guys know what we found. Thanks a lot.

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

ceengland7(at)gmail.com
Guest

Posted: Wed Jan 18, 2017 6:05 pm Post subject: Primer plunger?

On 1/18/2017 7:31 PM, Richard Pike wrote:

 	  Quote: 	
		   



 Thanks John & Charlie.

 After it starts, Ed usually lets it sit at a fast idle for around 5 minutes to let it slowly warm up to fully warm, and then no matter where we go for the rest of the day or how many times it is restarted, it behaves itself normally for the rest of the day.



 It is only after it sits for a month that we have to jump through these hoops. And since Ed is still working & gainfully employed, he some times doesn't get to fly for a month or so.



 If I understand correctly, you are saying it is acceptable to run a bypass around the Mikuni pulse pump and straight to the carbs.  So - now we have a fuel line coming up from below the tanks (where the Facet electric pump lives) and as it gets to the Mikuni pulse pump, I split the line and then join it again upstream of the Mikuni pulse pump. And then T it off to each of the 2 carbs.



 Now both the carbs are being fed by the Facet prior to start up - and then both the Mikuni and the Facet after startup? (Unless the float needles are sticking in the float needle seats prior to startup, and then nothing gets fed) (I will check this tomorrow by tapping on the floats while the Facet is running and seeing if anything changes/the float bowls fill up)



 Assuming that bypassing the Mikuni and letting the Facet apply pressure directly to the float needle assembly's, - which then respond properly - and that this resolves the problem - then the problem would be that until the Mikuni starts to pump because the engine is starting to run, that when the engine is not running then the Mikuni is not letting fuel flow freely through it. Correct?

 Which then begs the question - is that normal for a Mikuni? Should a Mikuni allow fuel to flow through it when there is pressure on the inlet side of the pump, but no pulses being received through the pulse port? I am thinking that a normal Mikuni ought to allow the fuel to flow through it. Comments?



 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kingsport, TN 3TN0


	


I should have bolded the statement 'for troubleshooting'.   I don't 

know Rotax 2 strokes at all, except in a generic 'almost all systems 

will work like this' kind of way. I'd never tell you to fly something 

that's a major mod without knowing from experience that it's safe. But 

*for troubleshooting*, bypassing the pulse pump will tell you if the 

pulse pump is blocking the flow instead of passing it properly. Actually 

flying the engine with only the Facet (pulse pump bypassed) *sounds* 

safe enough *to me*, since the Facet is presumably there to back up a 

pulse pump failure, and there are a lot of homebuilts with bigger 

engines flying with only a pair of Facets for fuel delivery. But I don't 

know Rotax 2strokes, and I don't know their carbs, at least on a 1st 

hand basis.



I can't imagine it being normal behavior for the pulse pump to block 

flow until it's getting pulses from the crankcase, but I don't *know* that.



On easiest 1st troubleshooting: John's probably correct; it's likely 

easier to just pull a fuel line off a carb than to splice around the 

pulse pump. But you're looking at the plane; pick what's easiest 1st & 

do it. Just do as John reminded, and do one thing at a time.



Back to (continuing?) safety: Just because the problem hasn't shown up 

while flying so far, doesn't mean it won't in the future. Whatever is 

blocking fuel flow is obviously defective, and it's a defect that isn't 

like a dead battery on a Lycoming, where it doesn't participate in 

engine operation after the engine starts. If the blockage ever becomes 

permanent, the engine will stop, and you can't know if/when that will 

happen.



Charlie

byoungplumbing(at)gmail.c
Guest

Posted: Wed Jan 18, 2017 6:13 pm Post subject: Primer plunger?

The mikuni pump should be 2 check valves with a chamber between them.    One side of the chamber is a diafram  The pulse line with a negative pulse,  pulls on a diafram increasing the volume of the chamber pulling fuel from the tank, followed by a positive pulse, pushing the fuel from the chamber to the carbs.  The 2 check valves should easily allow fuel to flow without the engine running. 

If the check valve membrane is starting to deteriorate due to age or incompatibility to the fuel,.  It may become sticky.   When allowed to dry out in a month's time it can stick to the valve seat not allowing fuel flow till it is forced off the seat.   Seemingly to work correctly till it dries out again.     

The float bowl needle valves can also become sticky.   Giving the same symptoms. 

To check for sticking valves in the mikuni .  At a time when it is hard to start.  remove a fuel line from the carb and check for fuel flow by squeezing the ball or turning on the faucet.   If there is flow check needle valves.    If nothing pull the fuel line to  the inlet of the mikuni .    If you have flow check or rebuild the mikuni.  If no flow check or replace the squeeze ball and or faucet pump. 

Boyd

Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Thu Jan 19, 2017 3:51 pm Post subject: Re: Primer plunger?

To all those who contributed suggestions: thank you. We found the problem; it was that the float needles would stick if the airplane sat too long between flights - and a contributing factor is that my airstrip is on an angle, uphill to land, downhill to take off.

Ed would push the Firestar out of his hangar and turn it uphill, which put the engine at about a 20 degree uphill angle. That, combined with maybe having it get gunky carbs if he let it sit for several weeks between flights was causing the float needles to stick in the seats, and blocking off the gas filling the float bowls.

It took a third set of eyes & brains to think outside the box - Dave said "Why don't you try and start it with the airplane facing down the hill, so the engine is sitting level, instead of sitting uphill at such an angle, and maybe making the float bowls and needles and seats not work right?"

Sometimes when you get somebody who is looking at the problem for the first time they will see it clearly.

Anyway, thanks to all. It started and ran perfect. During the test flight, it ran perfect. Smoothest and nicest you ever heard



Unfortunately, after landing, Ed ran off the runway and into the treeline, the Ivoprop hit a branch and chopped it off and threw it into the top of the right wing, cut the fabric in 3 places and bent the aileron tube, and broke off the wingtip counterbalance. Didn't break the IVO but it is not straight, I am guessing it is toast. At least nobody got hurt and it is somebody else's money...

Sigh... 

I will never get my Firefly built...

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

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