ArVeeNiner

ArVeeNiner

Well Known Member
Hi all:

So, I've read the thousands :D of posts regarding the placement of the fuel flow transducer supplied in the Dynon kit. I came up with before the mechanical pump...no after...no, on the engine...no, in line....ARRGHHH! Then I read a bit about placement of a fuel filter and I came up with after the electric fuel pump....no, before....no, at each tanks output. My head started to hurt!

So, I'm going to start with the basics. If I elect to mess with the fuel lines in the cockpit which have been in place for a very long time (read here that I'd rather not mess with them), what fuel filter do I use upstream of the electric pump? If I decide to put it on the engine side of the firewall, which do I use? I've see on Aircraft Spruce simple $4 inline glass filters much like I have in my VW Thing. I also know there are $200 filters too. With all our nice fuel lines running both in the cockpit and in the engine compartment, do we really want to revert to a simple glass filter with a clamp and a rubber hose at each end? How would you plumb that anyway?

I have a very basic set up. I have the Van's electric fuel pump and a carburator...that's it.
 
ArVeeNiner said:
Hi all:

So, I've read the thousands :D of posts regarding the placement of the fuel flow transducer supplied in the Dynon kit. I came up with before the mechanical pump...no after...no, on the engine...no, in line....ARRGHHH! Then I read a bit about placement of a fuel filter and I came up with after the electric fuel pump....no, before....no, at each tanks output. My head started to hurt!

So, I'm going to start with the basics. If I elect to mess with the fuel lines in the cockpit which have been in place for a very long time (read here that I'd rather not mess with them), what fuel filter do I use upstream of the electric pump? If I decide to put it on the engine side of the firewall, which do I use? I've see on Aircraft Spruce simple $4 inline glass filters much like I have in my VW Thing. I also know there are $200 filters too. With all our nice fuel lines running both in the cockpit and in the engine compartment, do we really want to revert to a simple glass filter with a clamp and a rubber hose at each end? How would you plumb that anyway?

I have a very basic set up. I have the Van's electric fuel pump and a carburator...that's it.
Click to expand...

First, a question: Do you plan on having a gascolator? If so, it serves as a crude filter.

Second, an opinion: If I planned on using filters, I'd put 'em in the wing roots. Eventually they will need to be changed and if they are in the cockpit, fuel is going to end up being spilled on the carpet, upholstry, etc. Also if (when?) the filters leak, the leaks won't be inside the passenger compartment.
 
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I suggest you build per the plans. There are thousands of RV's flying with a gascolator.

In my case the Dynon fuel flow is after the gascolator and works fine. Check my web site for pictures.
 
N941WR said:
I suggest you build per the plans. There are thousands of RV's flying with a gascolator.

In my case the Dynon fuel flow is after the gascolator and works fine. Check my web site for pictures.
Click to expand...


Yes, I have the gascolator supplied by Van's. So, that can take the place of a fuel filter?
 
Flow Ezy

I've always used a filter after the selector, this protects the electric fuel pump from debris/clogging. The flow Ezy 3ILA works perfect and is available in your choice of elements, I use the 74micron size.
 
N941WR said:
That IS the filter.
Click to expand...

You know, that's what I thought but I started reading about all these other posts concerning filters and such and I started wondering. So is all this filter talk only a concern if you have FI? I think there is some sort of super electric pump that some people put in near the fuel valve that has a filter near it. Maybe you don't need a gascolator for this set up?

The bottom line is, since the gascolator is the filter, it looks like I'm good to go w/o adding an additional filter, unless I want to put one upstream from the electric fuel pump.

Thanks!!!
 
ArVeeNiner said:
... So is all this filter talk only a concern if you have FI? I think there is some sort of super electric pump that some people put in near the fuel valve that has a filter near it. Maybe you don't need a gascolator for this set up?
...
Thanks!!!
Click to expand...
IO engines use a high pressure fuel pump and drop the gascolator, thus their need for an inline filter. Also, the UK requires filters on each tank, thus some mount gascolators or filters in each wing root.

Most certified planes run with one simple gascolator, if they have a carb. They have been using them for years and they seem to work fine. BTW, gascolators also work as a water trap, which most filters do not.
 
fuel filter inside the carb

There is also a fuel filter inside the carb of my O-360. It's about 3" long, about 3/8" wide, looks like a brass screen that's been rolled, and it receives fuel from the fuel line. It's easily ruined if you do not allow it to center as you attach the fuel line to the carb.

Ask me how I know.
 
Pre-Filter

When I was running a carb I had the FF xmtr located after the facet pump, before the gascolator. Both the facet pump and the FF xmtr have small inlets and can get clogged with debris which would totally block fuel flow. Now that I have switched to FI I still run the same filter in the same location to protect the high pressure (I used a Weldon) electric pump which is probably less prone to clogging than the facet but it is still a good idea to protect the pump from debris which should extend the life of the pump. The design is basically the same as the plans if installing the AFP high pressure pump so this is nothing new.
 
Seeing that Walt has been my technical and spiritual guide during my entire build process, I installed the in-line filter that he recommended.

It was an easy retrofit to put it in between the fuel valve and facet pump. After running fuel through the system before the 1st engine start, it was very easy to remove and check for debris.
 
Walt said:
... Both the facet pump and the FF xmtr have small inlets and can get clogged with debris which would totally block fuel flow...
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Walt,

Are they so small that something that gets past the screens in my tanks will plug? I would think that anything that could clog those could also clog your fuel filter. Just typing out loud.
 
Well the screens in the tank are long with lots of surface area and are rather course mesh so they will stop the big stuff, but small particles and other stringy debris can certainly get past it. I believe someone posted sometime back about a plugged inlet on the facet pump, and facet also recommends a filter on the inlet for just that reason. The flow ezy filter is about 5" x 1 1/2" dia and has a large surface area SS cleanable screen. It is basically the same filter that AFP uses with the fuel pump kit which has been proven as effective and reliable.
 
Walt,

Thanks for the info!

I used the $15 fuel pickup lines from Van's with the screen safetywired and prosealed on the end. So they should stop the majority of the big stuff.

cat-med_fuel-pickup.jpg
 
Watch out if anyone is going with the automotive style in line filters as the above link showed. Often these come in 2 or more micron ratings...how fine of particles they filter. The average 100 micron ones typicaly use a fine stainless steel mesh for the filter element and should work fine. The tighter ones like 10 micron often have a paper element, that when exposed to water swell up and clog really fast. We have had that problem on some of our performance boat engines at work, and have to make sure we have a water seperator before any paper element filters, or use the stainless or bronze elements.
 
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