Tip: Electric fuel pump setup

[frankh]

The little square solid state pumps (although I don't know of one that will make 11.5 psi) are internally relieved so no pressure relief valve is required..This is what I used on my carbed zodiac and the pumps made about 6psi.

Whats more i did not put filters in front of these pumps as they apparently pumped all kinds of stuff quite well. Thus they were even better than the rollervane pumps form a vapour lock perspective.

Depending on what pump you end up with you might put the filter before or after the pump.

A nice simple and very compact solution.

Frank

[rocketbob]

Facet makes them which run at 11.5 psi. Have a look here: http://www.facet-purolator.com/index...d=16&Itemid=31 Now if I can only find them...

The PS-5C needs 9-14 psi, so these should work fine.

I've never had any issues with the Facet boost pump in my RV.

And I can't think of a reason not to run both at the same time all of the time, unless you run a tank dry...

[frankh]

Probably find one will make moe pressure than the other..In my Zodiac this resulted in one of the pumps doing pretty much all of the pumping, so switching pumps was required to balance the fuel load.

Frank

[Norman CYYJ]

Bob I used one of those high pressure pumps to pump oil on the smoke system that I built. Used it in Mark's F1 worked great. Cheap and light weight.

[airguy]

Originally Posted by rocketbob

And I can't think of a reason not to run both at the same time all of the time, unless you run a tank dry...

Running them both all the time will not give you warning of an in-flight fuel pump failure. You'll just be going merrily along until your out-of-balance wing condition becomes obvious to you, and then you've got control issues while trying to land. Running only one pump at a time while in cruise will make you instantly aware of a dead pump when you try to change tanks. At that point you're still far enough away from a serious wing imbalance to make a relatively easy landing.

The pumps are constantly pushing against their respective pressure relief before T-ing into the single line going forward, and if you have both pumps operating, the one that has the pressure relief set at the lower value (what are the odds they will be exactly the same?) will be pumping all the fuel, resulting in one light tank and one heavy tank.

[rocketbob]

After a bit deliberation I've decided to go this route, and am going to pull the fuel selector out and not use a mechanical pump on the engine. Since I'm running the PS-5C pressure carb (poor man's throttle body injection), I need 9-14psi. I ordered some Facet 40185 pumps, which are rated at 9-11.5psi. These are the high pressure versions of the cheap and super reliable Facet boost pumps used in carb'ed installations. The plan is to install two of these cube pumps in each wingroot. These pumps have a built-in check valve, but I am adding additional check valves just like how Frank has his set up since one open check valve can cause a system failure. One or both pumps will be running for normal cruise, the other two are boost/backup pumps. These will be wired to the e-bus which is schottky-diode isolated from all power sources, so that in the event of a battery short/failure or main bus short power is still available and power is available to both ignitions and the pumps. Sounds complicated but it really is dirt simple the way I'm going to have things wired.

I like this system alot now that I think about it because it gets rid of the troublesome mechanical pumps, gets rid of the fuel selector, and all of the mickey-mouse plumbing required. One other nice with the cube pumps is they only draw 1.6A.

[rocketbob]

Originally Posted by airguy

Running them both all the time will not give you warning of an in-flight fuel pump failure. You'll just be going merrily along until your out-of-balance wing condition becomes obvious to you, and then you've got control issues while trying to land.

Greg I've flown my RV a handful of times with one tank full, other tank empty, to empty the tank before removing the inline filter on the empty side to clean it. There's no control issue, it does require full aileron trim and a little bit of continuous stick pressure. No big deal at all.

[frankh]

Welcome to the dark side of no mechanical fuel pump....

Frank

[airguy]

Originally Posted by rocketbob

Greg I've flown my RV a handful of times with one tank full, other tank empty, to empty the tank before removing the inline filter on the empty side to clean it. There's no control issue, it does require full aileron trim and a little bit of continuous stick pressure. No big deal at all.

Not having had the opportunity to try that, I'll have to bow to the voice of experience on that one. I did try it once in a 172XP with about 12 knots crosswind component on landing, and it was a little more than I wanted to deal with on a regular basis.

[David-aviator]

Originally Posted by rocketbob

After a bit deliberation I've decided to go this route, and am going to pull the fuel selector out and not use a mechanical pump on the engine. Since I'm running the PS-5C pressure carb (poor man's throttle body injection), I need 9-14psi. I ordered some Facet 40185 pumps, which are rated at 9-11.5psi. These are the high pressure versions of the cheap and super reliable Facet boost pumps used in carb'ed installations. The plan is to install two of these cube pumps in each wingroot. These pumps have a built-in check valve, but I am adding additional check valves just like how Frank has his set up since one open check valve can cause a system failure. One or both pumps will be running for normal cruise, the other two are boost/backup pumps. These will be wired to the e-bus which is schottky-diode isolated from all power sources, so that in the event of a battery short/failure or main bus short power is still available and power is available to both ignitions and the pumps. Sounds complicated but it really is dirt simple the way I'm going to have things wired.

I like this system alot now that I think about it because it gets rid of the troublesome mechanical pumps, gets rid of the fuel selector, and all of the mickey-mouse plumbing required. One other nice with the cube pumps is they only draw 1.6A.

For sure it will work mechanically. From the electric point of view, are you going with 2 batteries? Not sure I understand "....the e-bus which is schottky-diode isolated from all power sources...."

With the Lycoming install, I decided to keep the 2 electric pumps from the Subaru system but got rid of a 15 pound battery and its associated wiring by keeping the mechanical pump. I guess it is a trade off. I learned today the mechanical pump becomes almost inaccessible once the exhaust system is installed. I forgot to hook up the drain line from it until today and it was some job getting the fitting and hose in.

Going electric has hits appeal but I will tell you it is not bullet proof. I had one engine shut down in flight with the Subaru due to a tripped poly fuse on EXPBUS and a friend had the same thing happen a couple weeks ago. In both cases the engine restarted by going to backup battery which uses different circuits but it sure gets your attention. I am presently looking forward to flying with an engine that will keep running if the electric system goes TU and am about 3 days away from firing the beast up.