Tank to carburettor fuel filtering

[Prop Nut]

In a recent thread, where someone was having trouble with an SC .15 engine, he uploaded a photograph showing a three line tank set-up, with a filter fitted to the feed line from the tank to the engine, a method I have seen advocated by Brian Winch. However, several respondents firmly advised removal of this filter, saying that filtering should be carried out only from the fuel can to the tank. Which is correct or, perhaps more importantly, why is there a divergence of opinion?

Edited By Hellcat on 24/07/2012 10:26:37

[Bob Cotsford]

How many opinions do you want? I bet you wil get more than two!

Me, I use a filter on the line from the container to the pump and nothing on the model, except the Texan where a filter clunk was the first to hand when replumbing the tank. Certainly it's easier to clear a blockage with a filter either in the container or between tank and engine rather than in the tank, but these in-line filters do tend to leak and admit air sooner or later.

Maybe I've been lucky these past decades, but it's worked for me.

[Ian Jones]

Wanting to do the best for one of my engines I fitted a fuel filter once. Two secondhand 'planes I bought had filters fitted, in one case actually in the tank. This what I found.

• If any foreign objects get into the fuel pipes then they will either block up the fuel filter or the fuel mixture needle. The remedy in either case is similar (provided the filter isn't in the tank!).
• It's another point of failure.
• The filter gauze itself can rot and break up over time.
• If a model isn't used for some time fuel residue clinging to the filter gauze and in the filter chamber can "jellify" (I thought I made that word up but the spell checker likes it!), causing fuel flow issues the next time the model is used.
• A filter can cause a restriction to the flow of fuel and tuning difficulties as a result.

I think that if the fuel system is clean and clean fuel is put in the tank, a filter is unnecessary.

No doubt there will be reports of "if only a filter had been in place the engine would have been saved" but on balance I have decided not to use them.

 

Edited By Ian Jones on 24/07/2012 11:03:54

[chris basson]

Maybe it overkill but my (hand driven) fuel pump has a filter on, the clunk in the tank has a filter & I have another filter in the Line between the tank & the carb...

Now I put it like that it Does sound like overkill but I haven't had any problem with blocked jets!

[fly boy3]

I only use a filter in the fuel container line. No fuel problems in over 20 years of ic flying. Now to touch some wood !. Cheers

[Steve Hargreaves - Moderator]

I filter my fuel before it goes in the tank.....the in line filters can caise problems with air & fuel leaks in my experience so I avoid them.....

[Reno Racer]

As Steve said.

I filter mine straight from Fuel can when filling the tank, keeping my entire aircraft fuel system clean and avoiding any air leaks or additional potential points of failure that inline filters may add.

Chris

[Peter Miller]

The main r eason for not having a filter in the line is this. That filter can slowly clog up, the final straw is when oit clogs to give you a lean run.

Now a blocked jet will stop your engine and you have to land.

A lean run can overheat your engine very badly and that can cook your engine.

I know which I prefer.

[Myron Beaumont]

Peter

I agree entirely. If no muck ever gets into the tank ,then what will give you a problem? Someone mentioned the exhaust gases that pressurise the tank in another thread a while back .But surely that is only microscopic particles of carbon..I've never had a problem with one filter in the supply line from the fuel bottle to the a/c tank ever .Another non existant problem being discussed in my humble (grumpy) opinion .I'm starting to get paranoic about all the problems that lots seem to have that I don't .If you have filters everywhere that is fine ? All you have to do everynow and again is back flush them all .No problems .End of story .Grhh

Nearly forgot , Why have a clunk which is a filter as well if it's difficult to get to .Do you really want to remove the tank to check it ??Put an in- line filter in a few accessible inches away if you want to,but why ? By the way ,I filter my fuel through a coffee filter paper and funnel before use and never found much to worry about

Edited By Myron Beaumont on 24/07/2012 19:35:25

[Engine Doctor]

As already said , If fuel is filtered when its put into the tank then an inline filter with all its associated problems like air leaks should be uneccesary .What is often overlooked is that some engines after long usage or a weak run, can exhaust some burnt oil/carbon particles that often find their way into the tank via the pressure pipe from the silencer . I have for some years now been using the sintered metal filter/ clunks sold by du-bro and ripmax . They filter the fuel extremely well without risk of air leaks like the inline type. Cost £2-3 and are a good investment. I even use them in petrol set ups as they dont clog like the felt type clunks and can be fitted into a standard size tank .