MOKI RADIAL Care and Maintenence
09-21-2021, 09:08 AM
#4676
My Feedback: (2)
Detlef,
Your advice is well taken. That is the way I will plumb the new pump.
Possibly I misinterpreted the directions in the APS manual.
I bypassed the top return line, and installed a separate continuous return line, or loop, which actually recirculates more fuel through the pump. My reasoning for doing this is because the top return line is restricted somewhat.
Question please. What is the main flaw in bypassing the top return line and having a continuous return directly from the outflow line ???
Do you know of any other pitfalls which may have contributed to the malfunction of the pump ???
Appreciate your expertise in this matter and glad your are responding in this forum. Your experience is valuable here.
Thanks and regards - J Tab
Your advice is well taken. That is the way I will plumb the new pump.
Possibly I misinterpreted the directions in the APS manual.
1) Insert a T-connector into you fill line. As in, insert a T-connector to the line which you use to fill your fuel-tank with.
2) Connect the Return of the pump to said T-connector
3) This will allow for a constant loop which will assist in bleeding you system and keeping it air-free. This connection is optional and will render the manual bleed unnecessary. Or install a separate return to your tank.
2) Connect the Return of the pump to said T-connector
3) This will allow for a constant loop which will assist in bleeding you system and keeping it air-free. This connection is optional and will render the manual bleed unnecessary. Or install a separate return to your tank.
I bypassed the top return line, and installed a separate continuous return line, or loop, which actually recirculates more fuel through the pump. My reasoning for doing this is because the top return line is restricted somewhat.
Question please. What is the main flaw in bypassing the top return line and having a continuous return directly from the outflow line ???
Do you know of any other pitfalls which may have contributed to the malfunction of the pump ???
Appreciate your expertise in this matter and glad your are responding in this forum. Your experience is valuable here.
Thanks and regards - J Tab
09-21-2021, 09:23 AM
#4677
Detlef,
Your advice is well taken. That is the way I will plumb the new pump.
Possibly I misinterpreted the directions in the APS manual.
I bypassed the top return line, and installed a separate continuous return line, or loop, which actually recirculates more fuel through the pump. My reasoning for doing this is because the top return line is restricted somewhat.
Question please. What is the main flaw in bypassing the top return line and having a continuous return directly from the outflow line ???
Do you know of any other pitfalls which may have contributed to the malfunction of the pump ???
Appreciate your expertise in this matter and glad your are responding in this forum. Your experience is valuable here.
Thanks and regards - J Tab
Your advice is well taken. That is the way I will plumb the new pump.
Possibly I misinterpreted the directions in the APS manual.
I bypassed the top return line, and installed a separate continuous return line, or loop, which actually recirculates more fuel through the pump. My reasoning for doing this is because the top return line is restricted somewhat.
Question please. What is the main flaw in bypassing the top return line and having a continuous return directly from the outflow line ???
Do you know of any other pitfalls which may have contributed to the malfunction of the pump ???
Appreciate your expertise in this matter and glad your are responding in this forum. Your experience is valuable here.
Thanks and regards - J Tab
Jtab,
is not so easy for me to explain in English. I didn't understand exactly how you routed the return line. How is the carburetor connected to the circuit? Does the "out" line of the pump only go past the carburetor or does it really end at the carburetor?
From where to where does your return line go?
A sketch would be very helpful.
09-21-2021, 09:51 AM
#4678
My Feedback: (2)
Jtab,
is not so easy for me to explain in English. I didn't understand exactly how you routed the return line. How is the carburetor connected to the circuit? Does the "out" line of the pump only go past the carburetor or does it really end at the carburetor?
From where to where does your return line go?
A sketch would be very helpful.
is not so easy for me to explain in English. I didn't understand exactly how you routed the return line. How is the carburetor connected to the circuit? Does the "out" line of the pump only go past the carburetor or does it really end at the carburetor?
From where to where does your return line go?
A sketch would be very helpful.
09-21-2021, 10:53 AM
#4679
Ok Jtab,
I think I got it.
You "out" line passes the carb instead of ending there. So you never reach the fuel pressure (around 0,3 bar) that the carb would like so much. Then you disconnected the carb pulse line as I understood, making it very hard for the carb to get the amount of fuel that the engine likes so much :-)
What you have built is a non-stable, uncontrolled situation. With your disconnected pulse line, the amount of fuel the carb gets here is exposed to some undefined circumstances ( you can call it luck)
Suggestion:
Install your lines like in the little sketch I found ( hope I am allowed to show that here?)
You see the "out" line ends at the carb, no T-piece there.
The return leads to the fill line of your tank, or maybe if you like give it its own tank port, doesnt matter.
The main return circuit is hidden inside the cap of the pump. The flow is there, after passing the pressure regulator, but all is factory set and well hidden. Dont care, it works fine.
The return port will automatically vent the pump, no need to care by the owner.
---
You will have to re-adjust the needles, as you had never had the correct fuel pressure so far , the way I understood your setup.
There is a good chance that your pump has run dry for some time, I cannot say that clearly.
Feel free to come back if you have more questions
I think I got it.
You "out" line passes the carb instead of ending there. So you never reach the fuel pressure (around 0,3 bar) that the carb would like so much. Then you disconnected the carb pulse line as I understood, making it very hard for the carb to get the amount of fuel that the engine likes so much :-)
What you have built is a non-stable, uncontrolled situation. With your disconnected pulse line, the amount of fuel the carb gets here is exposed to some undefined circumstances ( you can call it luck)
Suggestion:
Install your lines like in the little sketch I found ( hope I am allowed to show that here?)
You see the "out" line ends at the carb, no T-piece there.
The return leads to the fill line of your tank, or maybe if you like give it its own tank port, doesnt matter.
The main return circuit is hidden inside the cap of the pump. The flow is there, after passing the pressure regulator, but all is factory set and well hidden. Dont care, it works fine.
The return port will automatically vent the pump, no need to care by the owner.
---
You will have to re-adjust the needles, as you had never had the correct fuel pressure so far , the way I understood your setup.
There is a good chance that your pump has run dry for some time, I cannot say that clearly.
Feel free to come back if you have more questions
Last edited by Detlef Kunkel; 09-21-2021 at 11:37 AM.
09-21-2021, 01:13 PM
#4680
Need to clarify further, so you fully understand why the T is there. This fuel pump has no pressure regulator! and no membrane pump will last, it they don't have a flow. The motor will stop and burn.
The T bypass is a way to create a cheap regulator, based on a fixed 1,3mm hole!, instead there should have been a spring with set screw and a membrane involved, (like the one already inside the walbro) to regulate to a constant fuel pressure to the carburetor, and circulate back to fuel tank the fuel not needed, like in most autos.
The T bypass is a way to create a cheap regulator, based on a fixed 1,3mm hole!, instead there should have been a spring with set screw and a membrane involved, (like the one already inside the walbro) to regulate to a constant fuel pressure to the carburetor, and circulate back to fuel tank the fuel not needed, like in most autos.
09-21-2021, 01:47 PM
#4683
It bears repeating that I used this fuel pump on my Moki 180. The engine was VERY difficult to start (I discovered) because the pump was constantly flooding it.
I flew the aircraft many times with the pump, but always struggled to start the engine until I finally realized what was going on.
And YES, I had it plumbed exactly as instructed (with the T bypass)
I removed the pump completely and the engine was EASY to start and ran perfectly.... well until the braided ignition pick up cable/connector failed.
Also flew a Moki 250 with no pump. I simply cleaned the air pump tube every 4-5 flights. Never a problem.
IF using a fuel pump gives you peace of mind, have at it.
All it gave me was headaches.
I flew the aircraft many times with the pump, but always struggled to start the engine until I finally realized what was going on.
And YES, I had it plumbed exactly as instructed (with the T bypass)
I removed the pump completely and the engine was EASY to start and ran perfectly.... well until the braided ignition pick up cable/connector failed.
Also flew a Moki 250 with no pump. I simply cleaned the air pump tube every 4-5 flights. Never a problem.
IF using a fuel pump gives you peace of mind, have at it.
All it gave me was headaches.
09-21-2021, 09:13 PM
#4684
Need to clarify further, so you fully understand why the T is there. This fuel pump has no pressure regulator! and no membrane pump will last, it they don't have a flow. The motor will stop and burn.
The T bypass is a way to create a cheap regulator, based on a fixed 1,3mm hole!, instead there should have been a spring with set screw and a membrane involved, (like the one already inside the walbro) to regulate to a constant fuel pressure to the carburetor, and circulate back to fuel tank the fuel not needed, like in most autos.
The T bypass is a way to create a cheap regulator, based on a fixed 1,3mm hole!, instead there should have been a spring with set screw and a membrane involved, (like the one already inside the walbro) to regulate to a constant fuel pressure to the carburetor, and circulate back to fuel tank the fuel not needed, like in most autos.
Are we talking about different pumps?
JTab,
what pump is it exactly that you use?
It looks exactly like an APS pump, which I use most. And it has ( or should have) a pressure regulator.
The sound when it works doesnt differ much if the "out" circuit is open or not. No blocking of the motor.
The later style ( since some years on the market) have the return circuit integrated. You see this when you open the return line when running; only a few drops come out. The function of that is just bleeding the pump, there is no big return volume of fuel. This is circling inside the pump head
09-22-2021, 05:34 AM
#4685
My Feedback: (2)
Are we talking about different pumps?
JTab,
what pump is it exactly that you use?
It looks exactly like an APS pump, which I use most. And it has ( or should have) a pressure regulator.
The sound when it works doesnt differ much if the "out" circuit is open or not. No blocking of the motor.
The later style ( since some years on the market) have the return circuit integrated. You see this when you open the return line when running; only a few drops come out. The function of that is just bleeding the pump, there is no big return volume of fuel. This is circling inside the pump head
JTab,
what pump is it exactly that you use?
It looks exactly like an APS pump, which I use most. And it has ( or should have) a pressure regulator.
The sound when it works doesnt differ much if the "out" circuit is open or not. No blocking of the motor.
The later style ( since some years on the market) have the return circuit integrated. You see this when you open the return line when running; only a few drops come out. The function of that is just bleeding the pump, there is no big return volume of fuel. This is circling inside the pump head
As you said, by utilizing the top circuit return line, there is no big return volume of fuel. It only emits enough fuel to keep the pump primed.
The older pump works very well by utilizing a return circuit similar to my diagram. My way of bypassing keeps the pump supplied with much more fuel recirculating through it.
The pump still has much more than enough pressure to supply the carb with adequate fuel. Much more then depending on the pulse pump alone. The carb only takes the amount of fuel it requires.
In the case of my Valach 210, I still have a crankcase pressure line hooked up to the carb. Is serves as a backup in case the pump would fail. It also requires cleaning out just as the Moki pulse line does.
Somethings things no matter how old or new - just go caput.
Regards - J Tab
09-22-2021, 10:07 AM
#4686
Detlef, the pump that malfunctioned is a 2 year old Emcotec APS HV non-programmable on a 250. I also have an older APS on a 10 year old Moki 250 that does not have the return on top - and a APS HV programmable on a 5 year old Valach 210.
As you said, by utilizing the top circuit return line, there is no big return volume of fuel. It only emits enough fuel to keep the pump primed.
The older pump works very well by utilizing a return circuit similar to my diagram. My way of bypassing keeps the pump supplied with much more fuel recirculating through it.
The pump still has much more than enough pressure to supply the carb with adequate fuel. Much more then depending on the pulse pump alone. The carb only takes the amount of fuel it requires.
In the case of my Valach 210, I still have a crankcase pressure line hooked up to the carb. Is serves as a backup in case the pump would fail. It also requires cleaning out just as the Moki pulse line does.
Somethings things no matter how old or new - just go caput.
Regards - J Tab
As you said, by utilizing the top circuit return line, there is no big return volume of fuel. It only emits enough fuel to keep the pump primed.
The older pump works very well by utilizing a return circuit similar to my diagram. My way of bypassing keeps the pump supplied with much more fuel recirculating through it.
The pump still has much more than enough pressure to supply the carb with adequate fuel. Much more then depending on the pulse pump alone. The carb only takes the amount of fuel it requires.
In the case of my Valach 210, I still have a crankcase pressure line hooked up to the carb. Is serves as a backup in case the pump would fail. It also requires cleaning out just as the Moki pulse line does.
Somethings things no matter how old or new - just go caput.
Regards - J Tab
J Tab,
do you as well use a restriction in the return line in order to build up a decent pressure for the carb supply?
Makes absolutely sense in your routing.
09-22-2021, 10:11 AM
#4687
It bears repeating that I used this fuel pump on my Moki 180. The engine was VERY difficult to start (I discovered) because the pump was constantly flooding it.
I flew the aircraft many times with the pump, but always struggled to start the engine until I finally realized what was going on.
And YES, I had it plumbed exactly as instructed (with the T bypass)
I removed the pump completely and the engine was EASY to start and ran perfectly.... well until the braided ignition pick up cable/connector failed.
Also flew a Moki 250 with no pump. I simply cleaned the air pump tube every 4-5 flights. Never a problem.
IF using a fuel pump gives you peace of mind, have at it.
All it gave me was headaches.
I flew the aircraft many times with the pump, but always struggled to start the engine until I finally realized what was going on.
And YES, I had it plumbed exactly as instructed (with the T bypass)
I removed the pump completely and the engine was EASY to start and ran perfectly.... well until the braided ignition pick up cable/connector failed.
Also flew a Moki 250 with no pump. I simply cleaned the air pump tube every 4-5 flights. Never a problem.
IF using a fuel pump gives you peace of mind, have at it.
All it gave me was headaches.
Richard,
I guess you had the same effect as I had in a 250. The carb ( new engine) had a non- tight regulator valve, leading to flooding the engine when pump on and engine not running.
Its a fault of the carb, not of the pump I guess.
I have heard of one single pump with a broken regulator, it supplied too much fuel.
More often is what I ( we ) had, a problem with the regulator valve seat.
it had no effect at all when the engine was running.
09-22-2021, 11:22 AM
#4688
something else...
Friends,
the more I read and follow this, the more I think its getting time to get rid of that tiny litte chainsaw carbs.
Why not go for something else.
At least this came to my mind when a friend brought me his worn out badly disadjusted SU constant flow carbs from his Jaguar E-Type the other week.
Maybe not big for those used to big V-8 Edelbrock carbs, but for european scales a 2 inches carb ( 3 of them per engine) is not so small.
What will the poor Moki say to this :-)
the more I read and follow this, the more I think its getting time to get rid of that tiny litte chainsaw carbs.
Why not go for something else.
At least this came to my mind when a friend brought me his worn out badly disadjusted SU constant flow carbs from his Jaguar E-Type the other week.
Maybe not big for those used to big V-8 Edelbrock carbs, but for european scales a 2 inches carb ( 3 of them per engine) is not so small.
What will the poor Moki say to this :-)
09-22-2021, 01:02 PM
#4689
My Feedback: (2)
09-23-2021, 12:18 AM
#4690
Regarding using the built in Walbro fuel pump
In my Moki 180 I don’t use any external pump, I use the excellent built in Walbro pump and regulator that gets air pulses from the Moki!
Which I now have proof that it is quite an effective pump if it gets the right kind of air pulses, like what a 2 stroke crank case will produce and maybe the Moki pulse arrangement also does.
Since Moki made their own air “pulsator” piston solution, I wanted to use that idea for other gasoline converted glow engines that lack a proper air pulsation from crank case. And also see what pump capacity that could be expected.
So I built a similar arrangement, just to see how much fuel the carburetor can pump.
I used the numbers “mitchilito” gave me from his Moki. The piston got; bore and stroke 10 x 10mm 0,78cc I let it rotate at 4000 rpm. By a small electric motor, Connected it to an open Walbro carb, (metering system removed, so the gasoline could flow through the carb.)
And boy! what a pump action that took place, the carb could easily pull gasoline from a tank 1m below, and it squirted at least 300 mm out from the carb hole, so it was quite a flow!
If there is lack of pump action on the Moki, there maybe is a design flaw with their design or it wears out early.. needs regular service.., It would have been interesting to connect a T on the air hose between the “pulsator” and the carb, just to measure if there is any strong pulse action taking place.
(and I read some of you can see grease coming out from the pulse tube! Maybe because of worn out piston, where grease is pushed out by crank case pressure entering the cam ring area)
I prefer to try cure the root cause, rather than adding new items/problems, Now we know the Walbro can have the pump capacity needed!
And maybe the Moki little piston needs to be replaced regularly!
(the pulse pump below is just a prototype not intended to be put in a airplane, it needs refinements)
In my Moki 180 I don’t use any external pump, I use the excellent built in Walbro pump and regulator that gets air pulses from the Moki!
Which I now have proof that it is quite an effective pump if it gets the right kind of air pulses, like what a 2 stroke crank case will produce and maybe the Moki pulse arrangement also does.
Since Moki made their own air “pulsator” piston solution, I wanted to use that idea for other gasoline converted glow engines that lack a proper air pulsation from crank case. And also see what pump capacity that could be expected.
So I built a similar arrangement, just to see how much fuel the carburetor can pump.
I used the numbers “mitchilito” gave me from his Moki. The piston got; bore and stroke 10 x 10mm 0,78cc I let it rotate at 4000 rpm. By a small electric motor, Connected it to an open Walbro carb, (metering system removed, so the gasoline could flow through the carb.)
And boy! what a pump action that took place, the carb could easily pull gasoline from a tank 1m below, and it squirted at least 300 mm out from the carb hole, so it was quite a flow!
If there is lack of pump action on the Moki, there maybe is a design flaw with their design or it wears out early.. needs regular service.., It would have been interesting to connect a T on the air hose between the “pulsator” and the carb, just to measure if there is any strong pulse action taking place.
(and I read some of you can see grease coming out from the pulse tube! Maybe because of worn out piston, where grease is pushed out by crank case pressure entering the cam ring area)
I prefer to try cure the root cause, rather than adding new items/problems, Now we know the Walbro can have the pump capacity needed!
And maybe the Moki little piston needs to be replaced regularly!
(the pulse pump below is just a prototype not intended to be put in a airplane, it needs refinements)
09-23-2021, 07:06 AM
#4691
My Feedback: (2)
FYI. Can't explain exactly why this pump failed. There is a collet on the motor shaft that engages the pump gears. The collet was spinning freely and not driving the gears. I believe something caused the collet to become detached from the motor shaft ???
There are ball bearings and springs in the pump that possibly act as relief or check valves to recirculate fuel within the pump.
Additionally, when power was applied to the motor while it was installed in the plane, the motor became hot as if stalled or shorted.
After re-assembly, the motor ran freely without overheating, however it would not pump fuel because the motor shaft was not turning the gears. I yield to the experts.
There are ball bearings and springs in the pump that possibly act as relief or check valves to recirculate fuel within the pump.
Additionally, when power was applied to the motor while it was installed in the plane, the motor became hot as if stalled or shorted.
After re-assembly, the motor ran freely without overheating, however it would not pump fuel because the motor shaft was not turning the gears. I yield to the experts.
09-23-2021, 10:33 AM
#4692
My Feedback: (9)
Join Date: Sep 2005
Location: Chapel Hill, NC
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It bears repeating that I used this fuel pump on my Moki 180. The engine was VERY difficult to start (I discovered) because the pump was constantly flooding it.
I flew the aircraft many times with the pump, but always struggled to start the engine until I finally realized what was going on.
And YES, I had it plumbed exactly as instructed (with the T bypass)
I removed the pump completely and the engine was EASY to start and ran perfectly.... well until the braided ignition pick up cable/connector failed.
Also flew a Moki 250 with no pump. I simply cleaned the air pump tube every 4-5 flights. Never a problem.
IF using a fuel pump gives you peace of mind, have at it.
All it gave me was headaches.
I flew the aircraft many times with the pump, but always struggled to start the engine until I finally realized what was going on.
And YES, I had it plumbed exactly as instructed (with the T bypass)
I removed the pump completely and the engine was EASY to start and ran perfectly.... well until the braided ignition pick up cable/connector failed.
Also flew a Moki 250 with no pump. I simply cleaned the air pump tube every 4-5 flights. Never a problem.
IF using a fuel pump gives you peace of mind, have at it.
All it gave me was headaches.
09-24-2021, 08:33 AM
#4693
My Feedback: (4)
Join Date: Dec 2001
Location: Dayton, OH
Posts: 358
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I hate to say "I told you so" but............I told you so. Get rid of the pump. I run mine (Moki 250) with no pump what-so-ever. I've trashed the Walbro and substituted a OS 7D 2 stroke, glo-fuel carburetor. This set-up is in a COMPARF Corsair and flies great. It has a SEP 32" 3 blade CF prop, makes 3900RPM on the ground. In the air it unloads to 5000RPM at a level flight speed of 160MPH. These are telemetery ;nos. not guess work. The Walbro's throat area is way to big, fellas. And the pump is a band-aid fix that provides an additional, parallel path for engine failure. Get rid of them!
For more info and photos. Check out my previous posts on this thread.
For more info and photos. Check out my previous posts on this thread.
09-24-2021, 10:15 AM
#4694
And I say skip the pump and the 2 stroke glo-fuel carbs, and fix the malfunctioning Moki air "pulse generator", It does a good job for so many.. when it is working properly..! find the root cause!
measure what kind of pulses it produces.. if any!
measure what kind of pulses it produces.. if any!
09-24-2021, 11:04 PM
#4696
We are talking about not so primitive technical applications. There are reasons why in one case this works and that doesnt. Always.
I would never go and call a blanket statement "only this solution works"
If you look at the complete system here ( we should include the owner) , in consists of so many single parameters. And all of them count.
For example, when every single detail works at its best condition, this engine surely runs without pump. True. Period. Maybe not perfect ( I come back to that later) , but it does
But seen from an engine designers view, this fuel supply system is weak to the limit. You can prove it easily ( on any Moki radial) as you cannot set the full throttle neede really much too rich. If you try, you may find some revvs going down, but you cannot kill the engine like in a 2Stroke. Why?
Easy answer. The limit is not the needle, ( as Mr walbro had designed his layout) , no, its the delivery system (by Moki).
Easy to see that here is a conflict. It may work as long as every paramter is in the optimum range ( Fuel tank distance, tube length, filter, condition of the carb membrane , butterfly valves, regulator valve, sealing of the pulsation piston, clean pulse line etc etc. The list is long.
Any deterioration will show up. The engine not only does not get the fuel it needs, the fuel is injected with nearly no pressure. This leads to a worse atomization of the fuel. This again leads to an accumulation of non- atomized fuel drops ( which do not explode, just burn) and the cylinder that is sucking from this area ( bottom of the engine) gets wet drops of fuel until it quits burning.
Personally, if I see the very few ( explainable) problems with pumps ( often operators mistake or misinterpretaion of effects) compared to the thousands of lean and hot running engines, dead stick landings with a grease-closed pulse line, AND see what other benefits come when you operate the carb with the originally desigend fuel pressure, you may understand why I prefer to use pumps on 4-strokers by far.
But I do NOT say "Only this is good, get rid of those". Everybody must find his layout where he ( and hopefully the engine) feels well
BTW I sad above "... including owner"
I have had more than just a few talks with owners that were medium happy with their engine, and they never have dared to touch a needle.
Thinking that they loose warranty, or that they do not feel in the position to improve something that the "holy manufacturer" had set before. I dont know.
The best of them was some guy who asked me for help. I spent quite a while to set his engine (including valves with 0,7 mm of gap) and it really performed well that afternoon.
Next day he came and had the old problems back again.
I asked him what happened. --> He felt so unpleasant with the "non- original" needle setting ( allthough the engine went very fine) that he had set everything back to default over night.
Whish I had a picture of my face at that moment
Hard to comment on such experiences. It is not always in the engine...
Last edited by Detlef Kunkel; 09-25-2021 at 12:07 AM.
09-24-2021, 11:15 PM
#4697
[QUOTE=Jaketab;12695734]FYI. Can't explain exactly why this pump failed. There is a collet on the motor shaft that engages the pump gears. The collet was spinning freely and not driving the gears. I believe something caused the collet to become detached from the motor shaft ???
There are ball bearings and springs in the pump that possibly act as relief or check valves to recirculate fuel within the pump.
Additionally, when power was applied to the motor while it was installed in the plane, the motor became hot as if stalled or shorted.
After re-assembly, the motor ran freely without overheating, however it would not pump fuel because the motor shaft was not turning the gears. I yield to the experts.
Jake,
maybe something blocks or has blocked the gears. Maybe some dirt particles, or maybe the fitting inside the housing is too tight. Once I saw a gear with a bad runout. It stuck in the housing when centered on the shaft. This could have caused the colllet to come loose on the motor shaft.
You can maybe repair this, but I would prefer to replace it. You cannot say how much the motor has already suffered.
Even if you get the gears to run nicely, there is a risk remaining
There are ball bearings and springs in the pump that possibly act as relief or check valves to recirculate fuel within the pump.
Additionally, when power was applied to the motor while it was installed in the plane, the motor became hot as if stalled or shorted.
After re-assembly, the motor ran freely without overheating, however it would not pump fuel because the motor shaft was not turning the gears. I yield to the experts.
Jake,
maybe something blocks or has blocked the gears. Maybe some dirt particles, or maybe the fitting inside the housing is too tight. Once I saw a gear with a bad runout. It stuck in the housing when centered on the shaft. This could have caused the colllet to come loose on the motor shaft.
You can maybe repair this, but I would prefer to replace it. You cannot say how much the motor has already suffered.
Even if you get the gears to run nicely, there is a risk remaining
09-25-2021, 06:03 AM
#4698
My Feedback: (2)
Detlef, I do not have an engineering background, but from a user point of view the pump section seems to be hearty and well designed. The apparent point of failure was the collet attached to the motor shaft which turns the gears. After dissecting the pump, I would not want to run gasoline through it for fear that it may not be sealed properly and create a fire hazard. I will, at some later point, reattach the collet to the shaft and examine how well it pumps a non flammable liquid. A new pump is on the way. In the many pages of this thread, I believe this is the first posting where an APS pump failed. Can't say if others have had pump failure.
To each his choosing. I prefer my eggs cooked sunny side up with a runny yellow center.
Thanks - J Tab
To each his choosing. I prefer my eggs cooked sunny side up with a runny yellow center.
Thanks - J Tab
Last edited by Jaketab; 09-25-2021 at 06:14 AM.
The following users liked this post:
Detlef Kunkel (09-25-2021)
09-28-2021, 08:40 AM
#4700
My Feedback: (2)
FYI. Just to confirm my suspicion about why the APS Pump failed. I reattached the collet to the motor shaft with some JB Weld. Plumbed up to some smoke oil to test. The pump worked as it should.
I will not be reusing this pump because it has been unsealed, the JB won't hold over the long term, and I don't like the idea of loosing an expensive aircraft.
It would be interesting to know if anyone has had a pump failure. This is the only incident I can recall from this thread.
Thanks all,
J Tab
I will not be reusing this pump because it has been unsealed, the JB won't hold over the long term, and I don't like the idea of loosing an expensive aircraft.
It would be interesting to know if anyone has had a pump failure. This is the only incident I can recall from this thread.
Thanks all,
J Tab