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Installation of new AF Perf fuel pump

gear1

Well Known Member
After nearly 1800 hours of operation of our RV8, the original Airflow Performance boost pump has become increasingly noisy. It has finally gotten loud enough to cause concern, so rather than waiting for failure I decided to change the pump. The new pump is the Air Flow Performance #2090255, sold by Van's as "EF Airflow Fuel Pump-1." The new pump has vastly simplified the installation, as the bypass is internal to the assembly, eliminating the return line to a "T" at the fuel selector valve. The installation eliminated seven fittings and about 18" of fuel line. A very nice assembly! The photos show how neat it is:

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The photos of the fuel filter are a bit confusing. The line comes out the bottom of the fuel selector valve, and curves around to the back of the filter.
 
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Other than the fuel lines, is there anything supporting the weight (mass) of the filter??

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Other than the fuel lines, is there anything supporting the weight (mass) of the filter??

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Exactly my thought. I saw a similar setup in another 8, only with longer fuel lines on each end with the filter suspended by the hard aluminum lines and pointed out my concern to the builder. He did not seem to have much concern about it though.
 
Filter support

Good eye, Mike and Mehrdad,

I did not put in place the soft rubber cradles that will be used to support and damp the vibration of the filter. The cradles will support each end of the filter.

As I was removing the original plumbing for the pump, I discovered that the aft end of filter was rigidly attached (through several fittings) to the fuel selector valve, and flexibly at the front by the aluminum pipe going through the grommet in the gear tower. To me that was asking for fatigue problems at the fittings, although 1800 airframe hours seems to have shown that it works! Now, all of the lines are formed to be long enough to have a bit of flex to fend off vibration without overstress. The rubber cradles will provide the support and damping needed to protect the lines, and can be slipped out to allow for the filter to be removed at condition inspection time.

Thanks for the good observation!
 
Experimenting?

We're you experimenting before "finalizing" the configuration? Better to see how it works than to re-do it later!
 
This is timely as my older style pump suddenly locked up and blew a fuse. I will probably tinker with it first, but will probably end up getting a new pump. Does the new pump have the same distance from inlet and outlet? In other words is it a drop in replacement (besides the elimination of the recirculation line)?
 
New pump plumbing

Eric,

No it is not a direct drop in, as the inlet to outlet distance on the new pump is longer than the new one. So the return line is eliminated, and the suction line is shortened somewhat. I did not have to change the line from the output to the firewall.

Look at the markings on the fuel pump that you have. There should be a "Exxxx" (E followed by four numbers). This is the AIRTEX part number. AIRTEX is a major supplier of automotive fuel pumps. The number on the new pump is E2315, but I will check my old pump when I go to the hanger today and let you know this evening. You may be able to replace just the pump in your assembly and not have to modify the plumbing.

Airflow Performance has done an excellent job of converting a relatively inexpensive pump to a very effective aircraft unit. I would recommend either replacing the pump on your existing assembly or purchasing the updated Airflow performance assembly from Van's.
 
Thanks Craig, now that I look at the pictures and my pump, I can see it would take some additional plumbing modification beyond dealing with the no return line. Since I just want to get back in the air ASAP, I ordered a bare pump for less than $70 off of Amazon. Since it's a standard automotive part, I may as well find it from the quickest and/or cheapest place (in this case, probably both with 2 day shipping).

By the way, I removed it from the airplane tonight and played around with it using a spare battery. For whatever reason, it's locked up. I only hear a slight click every time I give it power.
 
Airtex Pump part number

Eric,

The pump that I removed is the same part number as the new one: E2315. I hope that you found one quickly.:)
 
Craig,
Thanks for the information.
I've been wondering about my pump, as it make plenty of static (that bleeds over all avionics), and a racket when it runs.
I wonder how long mine has left? 1 hr or 500?
The one I have is only 2 yrs and ~ 100 hrs old too.

Daddyman
N262 DF
Dues Paid 2014
 
Craig - Yes, mine said E2315 also. Hopefully what I ordered will be the same thing - looked like it in the pictures.
 
Would be interesting to see what it looks like inside .. if one of you guys with a failed unit could cut it open ... Wonder if the brushes are worn out .. or if the bearings / busing used on the pump shaft has given up ...
 
Cavitation in the fuel line

Craig, I learned this, you need to get the 90 degree bends out out that fuel line leading from the pump to the firewall. One Big Cirlcle! If you put a piece of Clear plastic tubing on the end where it comes out of the firewall and pump it into a bucket you will see tiny air bubbles, kind of like a propeller cavitating in the water. I don't know the fluild dynamics behind it but it happens! Try it. The result is a poor running engine………….trust me, I idid that!

Put some Gas in a Jug and hook it up directly to the fuel pump and then put that clear tubing on the outlet side on the firewall and watch what happens! Mr. Bubbles! And no, I was not drawing air on the intake side, had clear tubing there as well. Then try it with one continuos loop (Roller Coaster style) and see what happens!

Dave
 
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Replies to great comments

This thread has generated some interesting comments and questions.

Mike Starkey wondered how the filter would be supported. My solution is rather like the supports under a Roman Aquaduct, except that the supports are rubber, pinned to the cockpit floor:

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This arrangement allows me to remove the supports easily so that the filter can be inspected. I had more than twenty-five years' experience working on and engineering formula-type race cars wherein the engines were rigidly attached to the chassis - the vibration issues were huge, and this is the type of solution we would use to damp and support components.

David Clinton asked how much time left on the pump when It gets noisy. I believe that mine was already sticking occasionally, tripping the electronic circuit breaker. Sometimes the power on light would not illuminate; I thought it was the stick switch in my Infinity grip, but now think it was the "time out" period when the electronic CB tripped.

David Ciccari questioned the elongated loop, rather than a 360 degree loop. I replaced my original 360 degree loop because it was chafing on firewall longeron. The long loop was a convenience, as I could not make a 360 degree loop with my tubing bender. I could have made it tighter, but it has worked fine for two years and 400 hours' flight time. No bubbles in the fuel, as I checked for that after I installed the new pump. In fact, the elongated loop was the only piece of plumbing that did not need to be changed with the installation of the new pump.

And Jan asked that the bad pump be disassembled to determine the cause of failure. I am on the road till the end of the month, but will cut it open when I return home.

Thanks, everyone, for making this thread interesting.
 
FWIW, here's my install. I mounted the pump with Adel clamps to 1/8 x 1" flat stock that will be riveted and ProSealed to the floor, and made a foam-lined cradle out of aluminum U-channel for the fuel pump that'll be attached by similar means.

 
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