fuel flow sensor

I'm trying to install the fuel flow sensor that came with my I-K Technologies AIM-2 EMS. It requires a straight stretch of fuel line. The best place would be between the fuel selector valve and the aux. fuel pump that I have placed on the firewall like the -7's. However, the sensor is too tall to fit under the center floor cover. Anyone have any other location suggestions?

floor cover

Consider the floor location for the FF sensor and put a raised cover over it. With carpet/pad it will not be noticeable. The layout is:

Tanks > fuel selector + FF sensor + inline filter + pump + firewall + gascolator + mechanical pump + carb.

The inline filter acts like a reservoir or accumulator. The FF sensor can be placed biased forward so it is more under panel. The cover is not that obtrusive and could dish shape. A lot of builders have problems with inaccurate FF readings when mounting the FF sensor in different places (with out the proper orientation, straight tubing or too close to pumps. I also like the idea of keeping the sensor on the cooler side of the firewall. Good Luck. G

fuel sensor location

I echo the recommendation to put it between the selector and the aux pump.

I purchased an aluminum box from digi-key to make a 'blister' for the sensor in that location.

A handier person could make his own box.

The idea of an inline filter to act as a pulse damper is interesting... but it too may need a blister.

Vern Little, RV-9A

in-line fuel filter

vlittle said:

The idea of an inline filter to act as a pulse damper is interesting... but it too may need a blister. Vern Little, RV-9A

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Here are some small aluminum inline filters that are high flow and only about 1 in in dia.
http://www.edelbrock.com/automotive/fuelfilters.html
http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=109773&prmenbr=361

http://www.petersonfluidsys.com/fuelfilt.html
(bottom of page: 1 inch hex body, Pelted stainless steel 60 micron filter element)

G

When I installed my fuel flow sensor, the instructions said to put it between the gascolator and the engine driven fuel pump. That put it on the firewall behind the engine and near the air inlet for cabin heat. You can see my installation on this page and some others that follow. I had to raise it a bit with spacers and longer bolts after the initial installation.

http://www.n2prise.org/rv9a055.htm

Slide down to the September 26th entry and continue onto page 56 for the initial install. After that the next posting about it is on page 78 at this link:

http://www.n2prise.org/rv9a078.htm

It has worked fine just as you see it installed on page 78. The sensor has not had a problem with the waste heat from the cabin heater air valve.

Jerry K. Thorne
RV-9A N2PZ
Hobbs = 78.1 hours
www.n2prise.org

in-line fuel filters

George: I want to point out to anyone considering an in-line fuel filter to be very careful: Many automotive types will block water. This means that water in the filter will also stop the flow of fuel... not a good thing.

The Subie guys use filters all the time, I'm sure that they'd share their insight.

Vern Little
RV-9A

gmcjetpilot said:

Here are some small aluminum inline filters that are high flow and only about 1 in in dia.
http://www.edelbrock.com/automotive/fuelfilters.html
http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=109773&prmenbr=361
http://www.petersonfluidsys.com/fuelfilt.html
G

Click to expand...

Good to know

vlittle said:

George: I want to point out to anyone considering an in-line fuel filter to be very careful: Many automotive types will block water. This means that water in the filter will also stop the flow of fuel... not a good thing. The Subie guys use filters all the time, I'm sure that they'd share their insight. Vern Little RV-9A

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I did not know that, thanks. Where does it say that. I know the Non-sube RV guys have debated this. I know a lot of guys use in-line filters coming off each wing tank. I guess the idea is drain the tanks so water is not introduced, but still that would not be good to have a "water block". I know that there is some controversy about the filter element absorbing water and freeezing. Some have tested this theory and found it not true.

I don't understand how that would cause a problem if the filter is a wire mesh (for example: 60 micron (pelted) stainless steel screen); if you get a slug of water I would think it would pass thru the in-line filter, where the gascolator would pick it up. These in-line filters are really just a Fat tube with a wire mesh cone. I wonder if differnt filter materials can block water? If it does you are right, they are no good, but the ones I have seen are wire mesh. Any paper type filter would be a no-no. I don't know how metal would not allow water to pass thru. Regardless if you us an in-line filter test it with water, drain and than freeze the thing, than try to pass chilled (-0C) fuel. This would be the acid test, so to speak.

To eliminate any filter issue, you could remove the in-line filter element and just use the shell. The idea is little area for some air to be trapped to absorb and surges (air is compressible), not filter the fuel. Instead of a in-line fuel filter, you can put a "T" in the line and run the spare tube leg so air is trapped in it and cap it off. This makes a little accumulator. Matronics makes a little fuel accumulator sphere for this purpose.

On second thought an in-line filter is another maintenance / service requirment and being in the cockpit, servicing and fuel spilling would be a pain. Also using a tiny filter to pass all the fuel is against standard aircraft filter design, where you should use larger more course filters close to the tank and get smaller (finer) filters towards the engine. Regardless of the water issue, keep it simple, light and per plans is a good idea. I am going to try the system as I discribed without any in-line filter and add an accumulator if there is any large scale error. The only filter will be the gascolator.

N2prise: As far as mounting the FF sensor between the gascolator and the engine driven fuel pump. I can see and advantage in that you isolate the sensor form the electric pump (which is the source of pulses). That is why some see erroneous readings when the electric pump is on. The mechanical pump is steady? If it works it works! Cool. Good to know. I like the idea of having in the cool floor, but your design looks like a good alternative. Bottom line if it works it works. However the instructions do discuss having straight runs in and out of the FF sensor. The idea is as long as you have solid flow, not turbulent or unsteady pulsing flow, you are good to go.

G

"I don't understand how that would cause a problem if the filter is a wire mesh (for example: 60 micron (pelted) stainless steel screen); if you get a slug of water I would think it would pass thru the in-line filter, where the gascolator would pick it up. These in-line filters are really just a Fat tube with a wire mesh cone."

George, in fact I have a funnel for my boat that uses a stainless steel screen to seperate fuel from water. If I get water in my portable tank, I pour it through this funnel and it works well.

check http://www.mrfunnel.com/

These are the type of funnels I mentioned. It's not obvious, but a simple stainless mesh can stop a plug of water and prevent fuel flow. Hands up how many of you knew that one!

Vern

Very interesting

vlittle said:

George, in fact I have a funnel for my boat that uses a stainless steel screen to seperate fuel from water. If I get water in my portable tank, I pour it through this funnel and it works well. check http://www.mrfunnel.com/ Vern

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Hummmm interesting. "Stainless steel the mesh will never rust and because of the Teflon? coating. Lets fuel thru and not water? Who da thunk. I think if you use an in-line filter you need to test it, however I fold my hand. I am going with no filter except the gascolator and hope the selector valve. FF sensor and pump can handle the unfiltered fuel (except for the tank pick-up slots/holes). G

vlittle said:

"I don't understand how that would cause a problem if the filter is a wire mesh (for example: 60 micron (pelted) stainless steel screen); if you get a slug of water I would think it would pass thru the in-line filter, where the gascolator would pick it up. These in-line filters are really just a Fat tube with a wire mesh cone."

George, in fact I have a funnel for my boat that uses a stainless steel screen to seperate fuel from water. If I get water in my portable tank, I pour it through this funnel and it works well.

check http://www.mrfunnel.com/

These are the type of funnels I mentioned. It's not obvious, but a simple stainless mesh can stop a plug of water and prevent fuel flow. Hands up how many of you knew that one!

Vern

Click to expand...

Hand goes up...

I don't understand why people need another screen in there, the gascolator works great for seperating water and sediment. Certified aircraft have been doing it this way for 50+ years with no problem.

fuel filter

osxuser said:

Hand goes up...

I don't understand why people need another screen in there, the gascolator works great for separating water and sediment. Certified aircraft have been doing it this way for 50+ years with no problem.

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The original topic was FF sensor installation. I brought up the filter as a way to provide a little air trap, like an accumulator to smooth out any pulses that might affect the sensor. The idea is use the filter like this device:

http://www.matronics.com/fuelchec/dampener.html

If you took an aluminum inline filter and removed the element and "T" it off the fuel line, cap the open end, you can provide the same buffer.

G

Fuel Flow Sensor

One vendor I looked at, strongly suggests the fuel flow sensor be placed in between the engine driven fuel pump and the fuel carb/distributor.

Tanks > fuel selector > electric pump > firewall > gascolator > mechanical pump > FF sensor > carb.

Are there different types of FF sensors, with different recommended mounting locations? Reasons?

How does it work

N63TX said:

One vendor I looked at, strongly suggests the fuel flow sensor be placed in between the engine driven fuel pump and the fuel carb/distributor.

Tanks > fuel selector > electric pump > firewall > gascolator > mechanical pump > FF sensor > carb.

Are there different types of FF sensors, with different recommended mounting locations? Reasons?

Click to expand...

DOES IT WORK?

N63TX said:

One vendor I looked at, strongly suggests the fuel flow sensor be placed in between the engine driven fuel pump and the fuel carb/distributor..........................

Click to expand...

Sounds like you may have gotten that advice from the folks at Vision Microsystems. That is the location called out in the installation manual and my particular installation can be seen in the Building tips/Techniques Forum thread entitled VM-1000 Fuel Flow Transducer.

Rick Galati RV-6A "Darla" 75 hours
RV-8A empennage complete

Fuel Flow Sensor

gmcjetpilot said:

DOES IT WORK?

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Don't know as I have not tried it. The quiery to them as well as my question here, is just part of my info. gathering before deciding on what to use (& where to locate it).

Fuel Flow Sensor

Electronics International; but that makes at least 2 recommending that location. I like your mounting solution.

Is the RV-8A going to be "Darla 2" ?

Rick6a said:

Sounds like you may have gotten that advice from the folks at Vision Microsystems. That is the location called out in the installation manual and my particular installation can be seen in the Building tips/Techniques Forum thread entitled VM-1000 Fuel Flow Transducer.

Rick Galati RV-6A "Darla" 75 hours
RV-8A empennage complete

Click to expand...