I figured enough folks have had problems with facet pumps that this subject would be better in the open discussion area.

I'm still building my Cruzer, yet I'm at the point where "systems" are starting to be added. I purchased the Zenith complete FWF kit for the O-200.

The plans show the facet pump mounted on the engine side of firewall with only a single line. It seems that popular opinion says I should install a check-valved bypass around the aux facet pump just to provide an unobstructed fuel flow if the pump failed and blocked the outlet.

I don't want to re-invent the Zenith design. Has anyone placed the facet pump in the cabin, in front of the center console, with a tee before and after the pump to allow a second line?

Pics would be great if any are available.  Thanks!

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Awesome Clint! Thank you for that detailed analysis! 

This video might be a bit late to the party, but is certainly worth a look before planning a fuel system for an aircraft.  It is more of a general piping video than a fuel system video , but explains the "bubble restriction" phenomenon far better than I could.  Enjoy!


I found the photo of my 750 the day I had the off-field landing. It’s fairly flat with a lot of farm land around here. This field was as smooth as its probably going to get in this situation, so I was fortunate it was right under me. Look how the forrows align perfectly with the gear legs! 

Wow!  Perfectly spaced! You are causing me to re-think my choice of tires, I currently have the smaller cruiser tires on mine, fine for maintained grass strips, used price was right but I wonder how my nose gear would handle a similar situation.  The finish on your aircraft looks beautiful!   Is it all paint or a mix of vinyl?  Happy Thanksgiving all!

My advice to you is to contact another Zenith builder/owner who is also on this forum: Clint Gosch. He completed his scratch built CH-750 STOL powered by an O-200 (without a mechanical engine pump) that has the Facet fuel pump(s) and a bypass. Clint has done (in my opinion) extensive analysis of his own fuel system and would likely have some very helpful/insightful advice for you. 

Good point, Kevin; I'll look him up.

im flying a 601xl , O-200 without mechanical pump. Using two facet pumps in series (no bypass) System (as designed for a corvair installation)   last year some posts hinted a pump failure blocked flow, but after a few posts here discussion subsided. So far after 270 hours of use no problems to report.

Thanks, Christopher; yes, last year's thread on pump blockage was what got me to thinking. 

Glad to hear you've had no problems. But, it only takes one problem, right?  ;-)

I'm vacillating on this issue; I'm thinking that if I keep the Zenith design, I'll just have a personal limit of something like 100 hrs then change the pump. Ooops; then there's the infant mortality issue....

I had two Facet pumps with one pushing through the second pump.  The second pump failed right after start up and fuel flowed (pushed) through no problem.  When I  needed to pull the engine I opted to put mechanical pump on the engine (@ near $3,000.00) and never expect to have it go real quite real quick.   With low wings I have to have a pump.

Hi Carl,

I have a 912 ULS in my 701. The fuel line comes through the Fire wall. there is a tee as soon as it comes through. One line from tee goes to faucet pump attached to firewall and other goes into a Andair check valve. The line leaving the faucet pump and the line leaving the check valve meet into a tee once again and one line goes to mechanical pump at front of motor and from there to the carbs. Hope this helps.

Thanks, Gary; by any chance do you have a picture of the plumbing?  I understand the text you wrote, but just looking for hints on the gyrations it goes thru....

Well, at this point, based on responses thus far, plus the excellent write-up and analysis by Clint, I'm leaning towards a no-pump, full gravity flow system, just like a Cessna (well, with the inclusion of an L-R-Both selector). I can always add a pump after the fact. This is a Cruzer, not a STOL, so I don't expect ridiculous angles of attack etc. The non-pump scenarios provide the highest rate of flow, close to 3.5x the typical O-200 fuel burn. Of course, I'll do nose and tail-high flow testing once I get to that point.


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