Facet fuel pump

[Allen Sutphin 705]

Just curious if any of you that are using an electric fuel pump, do you ever run it constantly or just use it to fill the carb bowls and then shut it off. Some also use it for take-off and then shut it off. I used one on my challenger as a back up with it normally off. I have experience with continuous GA pumps in low wing aircraft but don't really deal with low wing experimentals very often. I mainly deal with rag and tube type aircraft anymore. (mainly because the are more popular).

[1avidflyer 1983]

I have an electric fuel pump on my Avid MK IV.  Engine is a Jabiru which has a mechanical fuel pump that I eventually removed because it was making to much pressure.  I only use the electric pump for take off, and let gravity and the ram air tubes in the gas caps do the rest.  It worked tonight for .6 hr, and has for the last 2 or 3 hundred hours.  I never ran one with the two stroke engines though.  JImChuk

[Allen Sutphin 705]

Ram air pressure does help a good bit on the flow. My header tank is also vented the same as the gas caps. Most 2 stroke carb floats will handle about 5-6 PSI before being overwhelmed. And normally need 2-3 PSI to have good flow and operate correctly. One reason the pulse pump works so good is its RPM based, more RPM, the faster the pulses, thus more fuel available. I did my flow test with the header tank only to get the min GPH flow.

[nlappos 413]

I have a Rotax 670, and I installed a 2 to 4 psi Facet pump wired to the master switch, it runs all the time. 

[1avidflyer 1983]

Bing 64 (like used on the 912) and bing 94 that Jabiru uses cannot take a lot for fuel pressure or they will start bypassing the float valve.  That is the problem I had before I got rid of the mechanical fuel pump.  That was the reason for a dead stick landing.  Rotax's newer 912  fuel pumps produced more pressure then the early ones, and that is why they now want you to use a return line back to the tanks.  Can't say for sure on the type 54 like is used on the 2 strokes, but I suppose it is limited on the pressure it can take as well.  JImChuk

[Allen Sutphin 705]

Bing 54's start bypassing at about 5-6 PSI. And depending on the float valve condition, maybe less.

[akflyer 1427]

I have a Rotax 670, and I installed a 2 to 4 psi Facet pump wired to the master switch, it runs all the time. 

Nick,

Did you experience surging issues with your 670 at take off?  It seems the one in Bobs plane will hold 63-6350 for around 30 seconds or so then it starts surging, if I pull the throttle back to around 6100 it will go all day long.

I am really impressed with the 670 at sea level but still have a few bugs to work out on it.

 

[akflyer 1427]

I have one for a back up on my Avid, I only use it when needed.  Twice when fuel filters were plugging off it saved my bacon by helping to keep enough fuel flowing to get back on the ground safely.  I keep a close eye on my fuel flow meter and if it gets below what is normal I kick the pump on.

 

[ChrisBolkan 130]

I have my ignition "start" switch wired downstream of my Facet fuel pump switch/breaker. (it is one of those toggle switch breakers) The fuel pump must be on for the engine to start (It's a 912). Once the engine starts I generally turn it off almost immediately and don't use it during any phases of flight. It's basically to generate initial fuel pressure for start and to use in case of a reduced fuel flow emergency, which I have never experienced thankfully.

I wired it this way because I thought it made sense, and it saved me a separate fuse/breaker for the start switch.

[Richard Smith 32]

I have 2 facet pumps on my avid and 1 runs continuously and the other is for take off and landing.

[Dusty 126]

I use a facet 4 psi pump. It is turned on before startup to test its pressure. Start is with it off to check the mechanical pump pressure. Takeoff and landings the electric pump is on. The pressure with both running is 5.2 pound,I also have a bypass on both pumps with a one way valve so if one pump blocks it is bypassed by the other. I currently have a problem with my facet as with the bypass clamped off I have severely restricted fuel flow,these pumps can give problems. My first aftermarket facet lookalike pump failed internally and wouldn't make more than 1 pound pressure .Yes I am paranoid about fuel flow but have witnessed an early 912 pump fail resulting in a forced landing. The 582 pumps appear to be nearly bulletproof with only the pulse line giving  problems. So for me the jury is out on this one!

[Allen Sutphin 705]

I have never had a Facet pump give me problems but like anything it can happen. There is a Chinese knock-off that looks just like a Facet. I may add a fuel pressure gauge in the system.

[1avidflyer 1983]

Avid did some testing after one of the owners ended up going down after his Mikuni pulse pump failed.  With ram air tubes on the fuel caps, the 582 engine would run on gravity feed alone  and push fuel through the  pulse pump.  The more things on a plane, the more things to go wrong....and at least in my case, the biggest possible problem is sitting in the left seat!  

[nlappos 413]

AKFlyer,

I had to work on the leaning of the engine since I fly at 6000 ft runway elevation. I had to back down the main jets to 165 to allow a good takeoff, at 180 the full throttle takeoffs bog down and I can't get over 4000 rpm. With the 165 I get a clean burn and 6550 rpm at 60 mph, at about 8 GPH, which equates to about 75 HP, just right for a 91 HP engine at 8,000 feet.. I reinstalled my Hacman, and the 180 jets, and now I just lean a bunch on takeoff to get a nice power situation. I also noticed that the under cowl temperatures were very high (I used my wife's digital meat thermometer to read the carb inlet temp), and it was a solid 25 degrees F above ambient, which also leans the air like crazy. I cut a hole in the forward right cowl, and used a plastic window scoop to blow fresh air on the rotax air cleaners, and the temp went down to about 5 to 10 degrees above ambient.

 

I use the Facet pump at Rotax Rick's advice, the regular small air pump is only good for 8 GPH or so, and the 670 can ask for a lot more, up to 13, so the extra electric pump provides that.

[Allen Sutphin 705]

I might have to add an air scoop to the cowl to get outside air to the fan intake. Can't really say at this time, but it is a possible solution if high temps show up. One advantage of water cooled over. air cooled.

[nlappos 413]

Allen,

I found that the high temperature under the cowl was enough to cause an over rich problem because the temperature alone is like an altitude increase. It was so bad before i installed the scoop that I can get excellent run up with cowling off, when I put the cowling on I couldn't get past 3800 RPM!

Edited 17 Aug 2019 by nlappos

[Allen Sutphin 705]

I don't see that as a problem for me due to the way I have my filters angled, but that's yet to be determined.