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503 fuel pump weep hole makes a mess. Update, Fixed
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Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Tue Jun 12, 2007 11:55 am Post subject: 503 fuel pump weep hole makes a mess. Update, Fixed

I have a kitfox with a 503 Rotax.  There aren't many people that will talk about them on the kitfox list so wonder if I might hear some opinions from you folks.



Fuel slobers out of the fuel pump weep hole and makes a mess on my firewall.  I have only 14 hours on the plane now and thought it was a defective fuel pump so put a new one on but it does the same thing.



I zip tied a 3/4 inch plastic tube under the hole to catch the weeping fuel.  It is still inconvenient because the catch tube is full after about two hours so I have to remember to empty it often.  Is this a common problem with the 503?  The people with 582s have never mentioned it.  Is there a different remedy for the slobering fuel pump?

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

Last edited by Tom Jones on Tue Jun 19, 2007 12:02 pm; edited 1 time in total

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Tue Jun 12, 2007 12:24 pm Post subject: 503 fuel pump weep hole makes a mess

Sure. Replace it with an electric Facet pump. (Assuming that the pump is 

below the level of your fuel tanks. In the wings? Not sure where the Kitfox 

tank is )



Or run a long catch tube down the firewall so it dumps the fuel overboard 

along the belly.

Not as noticable that way...



Richard Pike

MKIII N420P (420ldPoops)

---

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

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

olendorf

Joined: 06 Jul 2006
Posts: 140
Location: Schenectady, NY USA

Posted: Tue Jun 12, 2007 1:50 pm Post subject: Re: 503 fuel pump weep hole makes a mess

I've never seen more that a couple tiny condensation drops appear in my pulse line.  Something is amiss. It doesn't sound normal to me. No fuel should come out of that hole. Is your pulse line full of fuel also?



It is better to have the pulse line leaving the engine going up to the pump so if any fuel does get in the line it would drain back to the engine. If you can't move the pump higher then loop the line so it is going up for a few inches first then loop back down to the pump.

_________________
Scott Olendorf
Original Firestar, Rotax 447, Powerfin prop
Schenectady, NY
http://sites.google.com/site/kolbfirestar/

planecrazzzy
Guest

Posted: Tue Jun 12, 2007 2:09 pm Post subject: Re: 503 fuel pump weep hole makes a mess

??????????????????????????????????????????????????????



 I've never had any leaks outa mine..... I have WHITE upholstery under



it....a leak would definitely show up....



             Gotta Fly...

                             Mike & "Jaz" in MN

.

.

.

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Tue Jun 12, 2007 3:25 pm Post subject: Re: 503 fuel pump weep hole makes a mess

Thanks guys!  It sure does appear something is amiss if other 503s don't weep fuel out the fuel pump weep hole.  Here is some more information and a couple of photos of how the fuel pump is installed.



The pulse port is just under the bottom and in front of the front carb.  The pump is on the fire wall 9 inches higher than the pulse port in level flight.  The pulse line is 1/4 inch rubber automotive fuel injection line.  The front half of the line is mounted level under the carbs then the rear half travels up slope at about 45 degrees to the fuel pump.  This is how the kitfox manual shows to do the installation.



The pulse line is 20 inches long.  Rotax recomends a shorter line.  I can't tell if the line is full of fuel because it is not clear. Today after one hour of flight at 6000 RPM the catch tube had almost exactly one ounce of fuel in it.  The fuel in the catch tube is dirty black so I am pretty sure it came from the crank case.



Any more ideas why this is happening or how I can/should change the installation?

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_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

possums(at)bellsouth.net
Guest

Posted: Tue Jun 12, 2007 5:18 pm Post subject: 503 fuel pump weep hole makes a mess

At 07:25 PM 6/12/2007, you wrote:

 	  Quote: 	
		  



Thanks guys!  It sure does appear something is amiss if other 503s 

don't weep fuel out the fuel pump weep hole.  Here is some more 

information and a couple of photos of how the fuel pump is installed.

xactly one ounce of fuel in it.  The fuel in the catch tube is dirty 

black so I am pretty sure it came from the crank case.



Any more ideas why this is happening or how I can/should change the 

installation?



--------

Tom Jones

Classic IV, Phase one


	


Is it supposed to be horizontal like that? -- maybe it doesn't matter.

Malcolmbru(at)aol.com
Guest

Posted: Tue Jun 12, 2007 6:20 pm Post subject: 503 fuel pump weep hole makes a mess

the pulse line should only be 12 in long and of an harder  hose( ask  for pulse line)    black ruber line is not an good idea even thow kit  fox  suggest it I know this because I have a kit fox also if the pump is  leaking  it will come out the hole .   if the crank case is  filling up it will come out the hole.some time people will poke a wire in the  weep hole to clear it and a hole will develop in the diaphragm. I just rebuilt a  fuel pump on a KF LIte and it was leaking fuel out the weep hole just by trying  to start the motor a noticeable amount was leaking out the hole by just pulling  it over 6 times .  Are you going LSA?   malcolm  michigan    And I will be at the  fathers day fly in   KF  N347ex 



See what's free at AOL.com. 

  [quote][b]

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Tue Jun 12, 2007 8:20 pm Post subject: Re: 503 fuel pump weep hole makes a mess

 	  Quote: 	
		  It is better to have the pulse line leaving the engine going up to the pump so if any fuel does get in the line it would drain back to the engine. If you can't move the pump higher then loop the line so it is going up for a few inches first then loop back down to the pump. 	




The pump is 9 inches above the pulse port but the line is level from the port for about  10 inches then a 45 degree slope up to the pump.  Fuel may be pooling in the line and working its way up that gradual slope to the pump.  I have some clear pulse line on hand.  I could put that on with an immediate straingt up 7 inch rise from the port then level to the pump.  That would be about 22 inches total pulse line length though.  I will see if there is a place closer to the port to mount the pump.



 	  Quote: 	
		   if the pump is leaking it will come out the hole 	




This engine pump combination has done this from the beginning right out of the box.  I put a new pump on and it does the same thing.



  	  Quote: 	
		  if the crank case is filling up it will come out the hole 	




The engine runs perfictly.  Temps in the green and plugs brown.  Turns 6200 on full power climb 800 ft. per minute at 60 MPH.



 	  Quote: 	
		  Are you going LSA? 	


My Kitfox is regestered Experimental amature built.  I am a private pilot flying under sport pilot rules

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Wed Jun 13, 2007 5:07 am Post subject: Re: 503 fuel pump weep hole makes a mess

Speaking of weep holes on 503 Mikuni pump, can anyone tell me where in the following photos the weep hole is located? Also, is the pump supposed to mounted so that the pulse line inlet side of the pump is up or down or does it matter? I'm trying to help a guy inspect a Challenger with 503.



Thanks,

Thom in Buffalo

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Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Wed Jun 13, 2007 5:46 am Post subject: 503 fuel pump weep hole makes a mess

Tom,

Not all pumps have the weep hole.

Mount the pump so that the pulse line side is down so any liquid will  

drain out away from the pump diaphragm.

The diaphragm must always remain free to move with the pulse  

frequency to pump properly.

Only a pump with a slowly leaking diaphragm will benefit  from a weep  

hole if mounted properly.



Gene

On Jun 13, 2007, at 9:07 AM, Thom Riddle wrote:



 	  Quote: 	
		   

 <thomriddle(at)roadrunner.com>



 Speaking of weep holes on 503 Mikuni pump, can anyone tell me where  

 in the following photos the weep hole is located? Also, is the pump  

 supposed to mounted so that the pulse line inlet side of the pump  

 is up or down or does it matter? I'm trying to help a guy inspect a  

 Challenger with 503.



 Thanks,

 Thom in Buffalo





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=118189#118189





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olendorf

Joined: 06 Jul 2006
Posts: 140
Location: Schenectady, NY USA

Posted: Wed Jun 13, 2007 5:59 am Post subject: Re: 503 fuel pump weep hole makes a mess

Some pumps do not have the weep hole. Maybe they were for motorcycles or seedoos or something.  If it has a weep hole it will be on the pulse port side.  The hole should be the low spot so any fuel in there drains out sooner.



For the Kitfox guy. I can't even imagine having enough fuel in the pulse line to make it all the way to the pump. I would guess a bad fuel pump or the fuel lines are leaking and the fuel runs down the side of the pump and it only looks like it is coming out the weep hole.

_________________
Scott Olendorf
Original Firestar, Rotax 447, Powerfin prop
Schenectady, NY
http://sites.google.com/site/kolbfirestar/

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Wed Jun 13, 2007 6:16 am Post subject: Re: 503 fuel pump weep hole makes a mess

Thanks guys. Much appreciated. Looks like the Challenger has its fuel pump installed upside down, as I suspected.



Thom in Buffalo

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Wed Jun 13, 2007 6:27 am Post subject: Re: 503 fuel pump weep hole makes a mess

Here is a link to CPS's article on installing pulse pumps and weep holes and such.

http://www.800-airwolf.com/pdffiles/ARTICLES/part%2053.PDF

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

d-m-hague(at)comcast.net
Guest

Posted: Wed Jun 13, 2007 4:02 pm Post subject: 503 fuel pump weep hole makes a mess

At 09:59 AM 6/13/2007, olendorf wrote:

 	  Quote: 	
		  



Some pumps do not have the weep hole. Maybe they were for motorcycles or 

seedoos or something.


	


The stock Mikuni pumps don't have the hole; I believe it's added by Rotax 

(and other aircraft suppliers) as an added safety measure.



                                 -Dana



--

--

Most politicians aren't crooks, but the ones that are sure are making the 

other 10 percent look bad.

jindoguy(at)gmail.com
Guest

Posted: Wed Jun 13, 2007 6:44 pm Post subject: 503 fuel pump weep hole makes a mess

I have all three types of the Mikuni dual pumps that are currently on the market. The two most often found at ultralight suppliers are those pictured in the CPS article previously posted to this conversation. The third I found at a go kart shop. 

The oldest of my three is the one with one straight and two bent hose barbs. On this pump, the pulse port is a square brass fitting with a hose barb at 90 degrees pressed into a boss, about an 1/8th inch tall, on the back of the mounting plate. The weep hole in this style pump appears to be factory drilled. 

The one I bought from CPS last year is the one with all straight hose barbs. On this style, the pulse port boss is about 3/4" tall and the hose barb is pressed into the side of it. In the CPS article, Mike said they drill the weep hole on these and that appears to be correct. 

The third style is one I first saw on eBay this winter. I went searching online and found it at Go Kart Supply. This style has the pulse port boss cast into the front cover and the bent hose barbs are turned outward 90 degrees to the mounting surface of the pump. The weep hole is drilled in a small divot in the center of the pulse pump boss and appears to be done by the factory. 

My criteria for factory versus distributor drilling of the weep hole is simply whether it is centered where it's drilled. The one from CPS is drilled willy nilly, the other two have the hole centered in the fitting or the boss respectively. 



Rick



On 6/13/07, Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)> wrote:[quote] --> Kolb-List message posted by: Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)>



At 09:59 AM 6/13/2007, olendorf wrote:

 	  Quote: 	
		  --> Kolb-List message posted by: "olendorf" < olendorf(at)gmail.com (olendorf(at)gmail.com)>



Some pumps do not have the weep hole. Maybe they were for motorcycles or

seedoos or something.


	


The stock Mikuni pumps don't have the hole; I believe it's added by Rotax 

(and other aircraft suppliers) as an added safety measure.



                                 -Dana



--

--

Most politicians aren't crooks, but the ones that are sure are making the

other 10 percent look bad. 

when you live at the airport.  [quote][b]

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Sat Jun 16, 2007 11:20 am Post subject: Re: 503 fuel pump weep hole makes a mess

Here's an update on my weeping pulse pump.



I dismanteled both fuel pumps I have tried and both look to be in perfect shape.  I installed each pump, one at at time, and each leaked fuel out the weep hole.



I then  rerouted the pulse line so it goes straight up over the carb flanges imediately from the pulse port on the crankcase.  This is about 5 or 6 inches straight up.  This change made no difference in the amount of fuel leaking out the fuel pump weep hole.  Ingot about a half ounce in 7/10 of an hour flight today.  The line is still 21 inches long.  I can't  figure out a way to mount the pump closer and still have it higher than the pulse port.



I am still using automotive 30R9 rubber fuel injection hose for the pulse line.  Could the pulse line material...being rubber...have anything to do with the leaking weep hole?

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

jindoguy(at)gmail.com
Guest

Posted: Sat Jun 16, 2007 2:16 pm Post subject: 503 fuel pump weep hole makes a mess

Tom, I went into the archives to review the situation before I replied. I have a few questions.

You said you have about 60 hours on the airplane, is this true for the engine as well? Was the engine new when when you put it on the aircraft, or was it rebuilt? Did you do the breakin procedure exactly per the Rotax Installation Manual (page 21-1)? Have you had any cold seizures (to check, pull off the exhaust manifold and examine the pistons for signs of displaced metal)? Have you done a compression check lately? 

As I understand the pulse port, it should be just that, a port for a pressure wave to travel to the fuel pump diaphragm. No fluid should move through this port at all.

I'll go out on a limb and suggest that your engine has excessive blow by that is pressurizing the case when the pistons are in the compression/power part of the stroke before the transfer ports open. I base this on your description of the residue in your catch can is black in color suggesting it is contaminated by compression by products. 

You're lucky in that Clyde Poser is just on the other side of the Cascades from you. If nothing anyone has offered here has helped, contact him. He has a repair station and years of experience with the Rotax two stroke. If anyone knows where to look for your gremlin, it'll be him. 

Keep us all updated and good luck.



Rick



On 6/16/07, Tom Jones <nahsikhs(at)elltel.net (nahsikhs(at)elltel.net)> wrote: [quote]--> Kolb-List message posted by: "Tom Jones" < nahsikhs(at)elltel.net (nahsikhs(at)elltel.net)>



Here's an update on my weeping pulse pump.



I dismanteled both fuel pumps I have tried and both look to be in perfect shape.  I installed each pump, one at at time, and each leaked fuel out the weep hole. 



I then  rerouted the pulse line so it goes straight up over the carb flanges imediately from the pulse port on the crankcase.  This is about 5 or 6 inches straight up.  This change made no difference in the amount of fuel leaking out the fuel pump weep hole.  Ingot about a half ounce in 7/10 of an hour flight today.  The line is still 21 inches long.  I can't  figure out a way to mount the pump closer and still have it higher than the pulse port. 



I am still using automotive 30R9 rubber fuel injection hose for the pulse line.  Could the pulse line material...being rubber...have anything to do with the leaking weep hole?



--------

Tom Jones

Classic IV, Phase one 

503, Warp

Ellensburg, WA





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=118752#118752



 

when you live at the airport.  [quote][b]

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Sat Jun 16, 2007 2:27 pm Post subject: 503 fuel pump weep hole makes a mess

I would replace the rubber hose with a length of soft aluminum 1/4" fuel 

line, use a short length of rubber or urethane fuel line at each end to 

attach it to the pulse port and to the fuel pump. If what is coming out of 

your weep hole still continues to be black, then you have bigger problems 

than just a mess on your firewall ala Rick's reply.

Richard Pike

MKIII N420P (420ldPoops)

---

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

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

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Sat Jun 16, 2007 7:29 pm Post subject: Re: 503 fuel pump weep hole makes a mess

Okay to clarify some more. The engine now has 14 flight hours on it.  It was broken in according to the rotax manual.  Total engine run time including break in, prop adjustment, taxi testing etc. is about 20 hours.  The fuel pump leaked from the beginning, that is why I put a new one on.  The new pump leaks too.  No cold seisures.  Compression is good.  I think the leaked fuel is black because it is the condensate rotax speaks of and thus requires the weep hole in aircraft fuel pumps.  I think it is black because it is mostly oil.  I think the fuel/oil is able to work its way up to the pump because of the weep hole.



I will replace the rubber pulse line with a plastic one to see if it helps.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

ulflyer(at)verizon.net
Guest

Posted: Sat Jun 16, 2007 9:50 pm Post subject: 503 fuel pump weep hole makes a mess

What kind of tubing were you using, tubing made for vacuum 

applications or black automotive type fuel line?



You should be using tubing for vacuum application, example what they 

call pulse tubing sold by Lockwood and CPS, it has thicker walls so 

as not to soften the vacuum impulses.  The automotive type fuel line 

is not good as it too can compress under the pulses and soften the 

vacuum pulses.  It also can react to the 2-stroke oil and fuel 

causing its layers to separate.  These then can compress and reduce 

the strength of the vacuum pulses - no pulses equal no or reduced 

fuel flow.  A Pennzoil rep at a past safety seminar acknowledge the 

2-stroke oil together with the fuel breaks down automotive type fuel 

lines which is the reason you see a different type material used for 

fuel lines on 2-stroke marine fuel tanks.

jerb



At 10:29 PM 6/16/2007, you wrote:

 	  Quote: 	
		  

snip...

I will replace the rubber pulse line with a plastic one to see if it helps.



--------

Tom Jones

Classic IV, Phase one

503, Warp

Ellensburg, WA





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=118797#118797

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