RunRyder RC
WATCH
 1 page 881 views POST REPLY
HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › Does a fuel magnet require pressure to work?
05-29-2012 09:12 PM  6 years agoPost 1
BrianApp

rrVeteran

Grand Rapids, MI

My Posts: All  Forum  Topic

I have never used a fuel magnet before. Everything seems to be in good condition. When I draw fuel out to defuel the tank as soon as the fuel level gets to the top of the clunk I can see it drawing air into the clunk line. This happens with about 1/4" of fuel left in the tank and the sponge is still soaked.

Do these fuel magnets require tank pressure to draw fuel properly? I thought it should suck it dry when pumping it out but maybe without any tank pressure it normally sucks in some air as well.

PM  EMAIL  GALLERY  Attn:RR  Quote
05-29-2012 09:27 PM  6 years agoPost 2
rotor head33

rrApprentice

Louisiana-United States

My Posts: All  Forum  Topic

i always leave my tanks full or enough fuel to keep the clunk line covered in fuel. why not just leave it full? it'll only help keep the sponge saturated

Power is nothing without control

PM  EMAIL  GALLERY  Attn:RR  Quote
05-29-2012 09:56 PM  6 years agoPost 3
BrianApp

rrVeteran

Grand Rapids, MI

My Posts: All  Forum  Topic

I don't mind keeping some fuel in for storage. I am talking about when the engine is running. I don't want bubbles in the line when the engine is running and 1/2" of fuel left in the tank.

PM  EMAIL  GALLERY  Attn:RR  Quote
05-29-2012 10:10 PM  6 years agoPost 4
steve 01

rrProfessor

Grand Rapids MI

My Posts: All  Forum  Topic

The purpose of the fuel magnet is it stays wet with fuel so that when the clunk leaves the fuel it runs on the fuel in the magnet then when it dips back in it is recharged for the next time therefor it avoids getting air into the system. All motors require some type of pressure to push the fuel into the motor but the magnet itself is just a sponge and doesnt require pressure to work.When using a sponge type fuel magnet when running on muffler pressure it is very important to keep the magnet wet with fuel or the exhauset gases in the tank will ruin the sponge.Personally I run the OS bubbless clunk with great results sucks the fuel out to the last drop!

It is like a sponge if any part of it is wet the rest will get wet as well so as long as part of it is in fuel you wont suck air.

PM  EMAIL  GALLERY  Attn:RR  Quote
05-30-2012 02:25 AM  6 years agoPost 5
rotor head33

rrApprentice

Louisiana-United States

My Posts: All  Forum  Topic

how old is your element? was it fairly old? maybe it is old staid dry to long and is breaking down?

Power is nothing without control

PM  EMAIL  GALLERY  Attn:RR  Quote
05-30-2012 03:35 PM  6 years agoPost 6
marc8090

rrElite Veteran

Long Island, N.Y.

My Posts: All  Forum  Topic

To answer the original question, no, you do not need pressure to draw the fuel out of the tank at the end of the day. It is a quirk of the fuel magnet that it is difficult to draw the fuel out with your fuel pump as you describe. However, for whatever reason, when it's the engine running and drawing fuel it works just fine. And not to start an arguement, but saying all engines require some sort of pressure to push the fuel along is not correct. The engine vacuum will pull fuel out of the tank as long as air is allowed in. But to make things more consistent having the fuel moved to the engine under pressure surely helps.

PM  EMAIL  Attn:RR  Quote
05-30-2012 04:41 PM  6 years agoPost 7
steve 01

rrProfessor

Grand Rapids MI

My Posts: All  Forum  Topic

Without pressure at Wide open throttle the engine will go lean but yes it will run without pressure.

PM  EMAIL  GALLERY  Attn:RR  Quote
05-30-2012 05:18 PM  6 years agoPost 8
Jerry K

rrKey Veteran

Houston Area

My Posts: All  Forum  Topic

I have my electric fuel pump so it only pumps fuel in one direction.

PM  EMAIL  GALLERY  Attn:RR  Quote
05-30-2012 06:23 PM  6 years agoPost 9
wifeorheli

rrElite Veteran

reno, nevada usa

My Posts: All  Forum  Topic

Ive been running a magnet since day 1 i love em all they do is give you a extra second or more where the engine will keep running if magnet comes out of fuel also as long as ANY part of the magnet is touching fuel it will suck and stay wet its a great thing but you must take care of them and keep them wet. As far as i know EVERY system requires pressure to properly run whiether its exaust pressure or pumped. Ive had a pinhole in my pressure line and it leaned the whole system causing it to tune very unstable

Novarossi Motors U.S.A
www.PLanethobby.com
Team GrandRc.com
Team Byron Fuels
ZRC U.S.A. "PushGlo, SwitchGlo"

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
05-31-2012 01:12 AM  6 years agoPost 10
punkin71

rrApprentice

illinois

My Posts: All  Forum  Topic

Dont empty your tank at the end of your flying day, Keep it topped off until you fly again! With a fuel magnet you will need some method to supply pressure to the tank just as you do with a regular clunk, whether it be muffler or crankcase pressurized. With a fuel magnet you should notice the engine able to run much more constistent throughout the flight.

The one and only drawback I can think of with the fuel magnet is over time exhaust gasses will eat the magnet foam and the element should be checked and replaced when needed but if you refuel your tank immediately after flight those elements can lost a long time. Myself I will run a fuel magnet over header tank any day, why run the extra weight if you dont have to?

PM  EMAIL  GALLERY  Attn:RR  Quote
06-01-2012 11:17 PM  6 years agoPost 11
Cra-Z-1

rrApprentice

Washington,UT-USA

My Posts: All  Forum  Topic

To try and answer the question the OP is asking, I have seen the small air bubbles that you are talking about, while drawing the fuel out of the tank with my electric pump. I think that you will notice it to do that more with your pump, than you would see with the fuel line supplying fuel to the engine, as the rate at which the fuel is being supplied to the engine is much slower than as if drawing it out with a pump.

Naturally, the foam wants to absorb all that fuel, even if it is only partially submerged. If you pull fuel from it faster than it can absorb more fuel, then you are going to pull air from within the tank. You might take a glance at your fuel lines, and filter to see if you have air in your lines, when you land. I have sort of developed that habit, to catch on to possible issues with leaky grommets, fuel lines, tanks, etc.

PM  EMAIL  HOMEPAGE  Attn:RR  Quote
06-02-2012 12:02 AM  6 years agoPost 12
BrianApp

rrVeteran

Grand Rapids, MI

My Posts: All  Forum  Topic

That is kind of what I am now thinking. When I hand pump it out I am drawing it 10X faster than the engine will draw it. When under a normal draw that it is designed for it may work fine. I was looking to see if other people noticed the bubbles when defueling. Now that a few have said they have I will put it back in and give it a try. The real test (and the only one that matters) will be to watch (or listen to) it while the engine is running. I will run it dry once at a 6 inch hover and see if it leans before it runs dry.

PM  EMAIL  GALLERY  Attn:RR  Quote
06-02-2012 01:25 AM  6 years agoPost 13
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

All motors require some type of pressure to push the fuel into the motor
Well, no. Try as you might, you just can't "push" fuel into a motor.

With regard to the model engines we use (and most other motors that burn liquid fuel), you might want to read up on how the carburetors actually work, paying close attention to the descriptions involving the word "venturi".

The addition of muffler pressure is an attempt to insure more even needle settings and to provide more consistent tuning and engine runs, independent of the attitude of the aircraft and the relationship between the center-line of the needle-valve body and center of the tank.

Prior to the wide-spread use of mufflers, engines ran pretty well with the tank vented to nothing more than the atmosphere.

Even YS (and now OS), with their systems using crankcase pressure and a regulator, nothing is pushing fuel into the carb.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
06-02-2012 01:43 AM  6 years agoPost 14
Four Stroker

rrElite Veteran

Atlanta

My Posts: All  Forum  Topic

Dave;

That's the strangest thing you have ever said.

PM  EMAIL  GALLERY  Attn:RR  Quote
06-02-2012 02:04 AM  6 years agoPost 15
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

I'm sure I've said things more strange than that...

Pushing fuel into a motor is about as easy as pushing a rope uphill.

Air flowing through the carburetor venturi (due to low pressure inside the crankcase as the piston moves upward) necessarily speeds up as it passes through the narrowest point in the venturi. At the same time its velocity increases, the pressure in the vicinity drops (physics is our friend here). The needle valve spray-bar is located in this low-pressure zone in the carb. The other end of the spraybar eventually finds its way to the fuel supply in the tank, and if no other means are employed, to atmospheric pressure at the tank vent. This pressure differential is what causes fuel to flow into the motor.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
06-02-2012 04:09 AM  6 years agoPost 16
Cra-Z-1

rrApprentice

Washington,UT-USA

My Posts: All  Forum  Topic

I'm very happy with the performance of my fuel magnet, compared to using standard clunks. My engine performance was never so consistent; especially in nose down maneuvers, and I never notice air in my fuel lines after a run. You should be able to run that tank completely dry with that magnet. Thats the beauty of them.

I personally think that the pressure from the exhaust helps feed the "Carburetor" a moderately pressurized fuel source. Even if you accidentally leave your line pinched on your exhaust tube, and let the tank sit in the sun for a bit, it feeds you a nice consistent source of fuel, as you pull the line from the plug to refill the tank. Seen it many times, lol...

PM  EMAIL  HOMEPAGE  Attn:RR  Quote
06-02-2012 05:46 AM  6 years agoPost 17
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

Yes, muffler pressure is a big help in maintaining consistency in engine performance.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
06-12-2012 03:57 AM  6 years agoPost 18
BrianApp

rrVeteran

Grand Rapids, MI

My Posts: All  Forum  Topic

Just to follow up. I have ran the tank to near empty several times. It works just fine up to the last tiny bit of fuel. Then it goes screaming lean, as any pickup method would do. So, in practical use a fuel magnet works fine down to a tiny bit of fuel remaining despite what is seen when defueling it.

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 881 views POST REPLY
HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › Does a fuel magnet require pressure to work?
 Print TOPIC  Make Suggestion 

 4  Topic Subscribe

Saturday, November 17 - 1:19 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online