The real question to ask is what happens when the light comes on.If one is over an area with landing sites and help it sounds alike a good idea, On the other hand if its a remote area with no help ( e.g middle of Taklamakan) then an electric standby fuel pump seems like a good idea
It all depends on what caused the warning light to show.
If it's because of an unexpected leak from the tank or other part of the fuel system a pump will not help you.
But you've got at least a carb-full of fuel to give you extra thinking time.
Antoni Splitting or explosion of the fuel tank in the middle of the desert with two perfectly functioning fuel pumps would certainly be unexpected. I guess you cant win them all.
Joe: I have considered the GRT EFIS, but since I already had an EGT and CHT gauge, I did not want to spend the extra dollars.
mullacharjak: I have an electric fuel pump. I use it during take off and landings, and leave it off during flying. I am thinking that if the low pressure light starts flickering in flight, I can start the electric pump. If the lamp starts to flicker before take off, I will fix the problem before I take off.
Radfordc: Thanks for the update. I am going to install the switch after the filters and pump, close to the carburetor. What kind of fitting or union do you use, to connect the fuel hose to the switch?
Stroid: Sorry about hijacking your tread. That was not my intention. My biggest fear in flying, is having an engine stop during flight. Where I live there are lot of mountains and water, and good landing sites are not easy to find. I am glad you had an successful landing, and hope you find the solution to your engine problem.
Stroid: Sorry about hijacking your tread. That was not my intention. My biggest fear in flying, is having an engine stop during flight. Where I live there are lot of mountains and water, and good landing sites are not easy to find. I am glad you had an successful landing, and hope you find the solution to your engine problem.
Regards Petter
I feel for you, brother. I always told my students not to fly over anything they wouldn't care to land on. You need a BRS!
Have you got your fuel filter mounted before or after your pump? I've got mine mounted before (i.e. on the fuel tank side of the pump), so that any fuel going through the pump is already filtered.
Looking back through this thread I see that Keith1100 has a square type vacuum fuel pump.
In my experience these are not generally fitted with a weep hole for oil to escape from. In the UK we generally use the round Mikuni pumps. They have two outlets, one of which is normally closed off unless feeding a twin carb setup, and they have a metal block on the back with a 90 degree inlet for the vacuum tube. This block also has the very small weep hole, and when using one of these round pumps we try to mount them horizontal, so that any oil coming from the crankcase will drain out easily. If mounted horizontal then it doesn't matter if the pump is mounted above or below the crankcase vacuum outlet, because any fuel or oil that goes along the vacuum tube will drain out of the weep hole.
Is the round pump with 2 outlets of a better quality ? I thought I read something to that effect. I could switch to that pump if it is more reliable.
Bob.hood, thanks for the information in your post. I cannot access my pump as it is still bolted to the frame. But a peek-around picture with my phone shows my pump may have a weep hole, though unfortunately it is on the upper half of the pump. (The photo here is inverted so it looks the hole is on the lower half.)
What radfordc says is technically correct, however you can use the two outputs together for more capacity. Some of the square ones do not quite have the capacity for a 447 single carburetor at full throttle. Joe
Thanks, Joe. I will keep that as an upgrade option in future. Mine is only a 340 Kaw, so fuel flow demand may not be as high as a 447.
I am now in the process of re-positioning the existing pulse pump; And Bob Hood, I stand corrected on the weep hole. Mine does NOT have one. I took out the pump couple days ago to mount it higher and got a closer look.
What radfordc says is technically correct, however you can use the two outputs together for more capacity. Some of the square ones do not quite have the capacity for a 447 single carburetor at full throttle. Joe
What kind of pump doesn't work with a 447? I've only used Mikuni pumps that are correct for that engine.
You are correct on the Mikuni. The 447 requires 11 l/hr at full throttle. The rectangular Mikuni will do 14 L/hr. However there are Mikuni knockoffs that will not deliver the 11 l/hr so check before you buy. If the casting doesn't say Mikuni it isn't. Joe
Keith, You are correct. The dimple to the right of the letter "N" in Japan is where the weep hole is. The pump in the last pictures appears to NOT have the hole. It's hard to tell for sure in the picture of the pump that is installed in an airplane because of the angle, but I believe that pump has the weep hole. Another point of interest is that there are at least two different cover plates for the rectangular pump. I have one that has Mikuni, and Made in Japan cast in the cover, and another pump with MIC, MIKUNI corp. and JAPAN cast in the cover.
Keith, You are correct. The dimple to the right of the letter "N" in Japan is where the weep hole is. The pump in the last pictures appears to NOT have the hole. It's hard to tell for sure in the picture of the pump that is installed in an airplane because of the angle, but I believe that pump has the weep hole. Another point of interest is that there are at least two different cover plates for the rectangular pump. I have one that has Mikuni, and Made in Japan cast in the cover, and another pump with MIC, MIKUNI corp. and JAPAN cast in the cover.
Greg, Thanks for that clarification. That is helpful information. Thank you.
JBird had given me detailed instructions on how to set up their new engine that I purchased last year. They were very emphatic that the pulse tube from crankcase to the pulse pump should not exceed 4 inches, to get good fuel flow. But nowhere was it mentioned in their notes that the pump should be mounted slightly higher than the crankcase pulse aperture. That is how I ended up making this mistake. I will swap my pump for a round one after I fly a few hours.
You are correct on the Mikuni. The 447 requires 11 l/hr at full throttle. The rectangular Mikuni will do 14 L/hr. However there are Mikuni knockoffs that will not deliver the 11 l/hr so check before you buy. If the casting doesn't say Mikuni it isn't. Joe
Many microlights cruise at 11 litres per hour with a 447. My 447 Minimax did abt 10. I believe the full throttle consumption of a 447 is more like 25 litres per hour. The Rotax two-strokes all run rich at full throttle too.
The Mikuni dual output round pump has two outlets fed from the same internal chamber. You don't need to take both outlets and T them to one, just block one outlet for a single carb installation.
Just to repeat myself 'cos I think it's worth it: Remember to change the diaphragm every couple of years - essential as I found out. Just for that reason I wouldn't choose a square Mikuni for a 447 - the problem is likely to occur sooner.
I don't know why jbird was so emphatic about a 4 inch distance from crankcase to pump? I don't think I have ever seen a pulse pump line that short. Yes, the shorter the better but as I remember, 12 inches was the called out maximum for line length. And naturally you should be using the correct type of line. TTT
TTT, true, most resources quote 12 inches as upper limit for permissible length of pulse tube. I guess JBird's 4 inch recommendation is with specific reference to their schematic for fuel plumbing , which is supplied with the engine. The schematic shows only the following as essential items:
Fuel cock, primer bulb, fuel filter, pulse pump, carburetor (and choke circuit ) (A separate plunger circuit is optional but a useful addition.)
Since a Facet pump is not shown as a standard item, may be they wish to keep the length of pulse tube as short as possible so that fuel delivery does not come up short.
===
I just re-positioned my pulse pump so that the pulse tube travels upwards about 1 inch from crankcase to pump. The pulse tube length is now about 4.5 inches.
That don't look like pulse pump line Kieth. And I know that you know there IS a very physical difference. Wasn't it you that said you were going to get rid of the primer bulb & go with the enrichment plunger,? I'm to lazy to go back to search . TTT
If that's not Actual Pulse Line, get rid of it. Aircraft Spruce sells the right stuff. I would also think of how that's mounted and the length of line for vibration. Remember that engine shakes sometimes, and the pump should be isolated from that shaking, plus the strain on the line can be a negative.
I do have a 12 inch piece of a sturdier pipe lying in the kit JBird supplied with the engine, which I will cut and fit after I do a ground run of the engine and be certain the location of the pump is just right. ( Don't want to cut to a wrong length.)
Regarding the primer bulb, since my carb location is above the level of the fuselage tank, I need some mechanism to send fuel into the carb float chamber prior to start up. I have a plunger/primer too, but that wont fill the float bowl. Also, I feel the much discredited rubber primer bulb is not as bad as it is made out to be. Most failures have possibly taken place in older bulbs. If we replace the primer bulb once in 2 or 3 years as a regular wear item, they should not let you down. (There may be more informed opinion on this, I am listening.)
Puff, there is some slack tucked into the pulse line, though it may not be so readily seen from the picture. I kept an excess of about 3/4 inch above the minimum length required. But your suggestion has merit.
=== (I wonder if other members are also having a technical issue with this site. All my devices frequently show the site is down, with a message "Software error". Not sure if it is only my ISP or a technical issue with the server.)
Regarding the primer bulb, since my carb location is above the level of the fuselage tank, I need some mechanism to send fuel into the carb float chamber prior to start up. I have a plunger/primer too, but that wont fill the float bowl.
The primer injects fuel directly into the intake manifold. The engine will start and run for a few seconds on the initial prime, and the pulse pump will fill the carb bowls while the engine is running. I haven't used a squeeze bulb in 20 years.
Also, I feel the much discredited rubber primer bulb is not as bad as it is made out to be. Most failures have possibly taken place in older bulbs. If we replace the primer bulb once in 2 or 3 years as a regular wear item, they should not let you down. (There may be more informed opinion on this, I am listening.)
No doubt that squeeze bulbs work....most of the time. How often would one have to fail to constitute "acceptable"? I have seen brand new ones fail. I guarantee that if its not there it won't fail.
I'm sure that will work. I use the heavy wall clear tubing for both pulse line and for all my fuel lines, too. I quit using the blue tubing after seeing how poorly it lasted over time. After a few years I've seen it just fall apart. A friend ended up with 15 gals of 100LL in the bottom of his Kitfox when his blue line broke in two. The clear urethane is close to "lifetime".
(I wonder if other members are also having a technical issue with this site. All my devices frequently show the site is down, with a message "Software error". Not sure if it is only my ISP or a technical issue with the server.) I've been having the same problem. Eventually I gain access.
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