HKS fuel system
-
moushegiancarl
HKS fuel system
I have a HKS on a Soaring Gull The last couple of times I have flown for a duration of overone hour ,there occurs a throttling back on rpm's in flight.It is very brief and when trottling back up the problem will momentarily resolve itself only to have it occur again. The plane has both mechanical and electrical fuel pumps.I have been told to use electric on take off and landingsso I shut it off in flight. when hesitancy occurs I immediately switch on the electric.Both fuel lines and filters look clean and the spark plugs are also clean. I will be at the airport tomorrow to see which fuel pump I have. If it is the HKS style I will replace with the Mikuni. Do you think this is the problem ?If there is a Mukuni in place then what do you suggest? Thanks, Carl
-
wsweidemann
Re: HKS fuel system
Carl,
For what it is worth, my testimonial.
I have the original HKS pneumatic pump and a Facet electric. Typically I turn on the electric pump at startup and takeoff, pneumatic only while aloft, then electric pump on for landing. (I have occasionally forgotten to switch on the electric pump for landing...and nothing significant happened because of this omission.) My fuel line setup is plumbed in parallel. The total time on this machine is 400 hours.
I know Mark B likes Mikuni pumps.
The first thing I would look for in your case is old fuel filters (how much time on filters) and possible leaks in the fuel line connections. (Maybe introducing air somewhere?) It could also be something else, like a bad ground?
Skot Weidemann
For what it is worth, my testimonial.
I have the original HKS pneumatic pump and a Facet electric. Typically I turn on the electric pump at startup and takeoff, pneumatic only while aloft, then electric pump on for landing. (I have occasionally forgotten to switch on the electric pump for landing...and nothing significant happened because of this omission.) My fuel line setup is plumbed in parallel. The total time on this machine is 400 hours.
I know Mark B likes Mikuni pumps.
The first thing I would look for in your case is old fuel filters (how much time on filters) and possible leaks in the fuel line connections. (Maybe introducing air somewhere?) It could also be something else, like a bad ground?
Skot Weidemann
-
earthstaraircraft
Re: HKS fuel system
The throttle friction may be to loose.
There is a pair of nuts on the throttle pivot bolt and a nylon washer between the throttle handle and the throttle base plate that gives the tension on the handle when the inner nut is tightened. You may need a thin 7/16 wrench to hold the inner nut, after you have the tension you want. Hold inner nut and tighten outer nut against the inner nut. This locks the inner not so in will hold tension for another 10 years.
If you still have a problem than look at EGT temps. Just guessing since in the last 6000 hrs of flying with HKS and other engines, throttle tension has always been the cause of lazy engine syndrome.
Happy Flying
Mark
Sent from my iPhone
There is a pair of nuts on the throttle pivot bolt and a nylon washer between the throttle handle and the throttle base plate that gives the tension on the handle when the inner nut is tightened. You may need a thin 7/16 wrench to hold the inner nut, after you have the tension you want. Hold inner nut and tighten outer nut against the inner nut. This locks the inner not so in will hold tension for another 10 years.
If you still have a problem than look at EGT temps. Just guessing since in the last 6000 hrs of flying with HKS and other engines, throttle tension has always been the cause of lazy engine syndrome.
Happy Flying
Mark
Sent from my iPhone
-
earthstaraircraft
Re: HKS fuel system
I have had costumers that left the back up electric pump on all the time.
It will last a total of 500 hrs of pump
On time. Than wen it fails you won't know it failed. Unless you check it In your pre flight by turning it on before starting the engine so you can hear it but this is not fool prof but good enough since the electric pump is not necessary, except if the vacuum pump fails, I have never had a vacuum pump fail but have hade the engine almost quit at idle due to leaks in suction fuel line. So this is wen I would turn on the electric fuel pump, until I fixed the fuel line connections,
The most common cause for leaks is the use of werm drive hose clamps, we use .032 safety wire raped twice around the tube and than twisted with a safety wire pliers than cut the tail 3/4 inch out and bend it in half and against its self so that the sharp cut end does not cut you next time you reach in to work
On something.
Happy Flying
Mark
Sent from my iPhone
It will last a total of 500 hrs of pump
On time. Than wen it fails you won't know it failed. Unless you check it In your pre flight by turning it on before starting the engine so you can hear it but this is not fool prof but good enough since the electric pump is not necessary, except if the vacuum pump fails, I have never had a vacuum pump fail but have hade the engine almost quit at idle due to leaks in suction fuel line. So this is wen I would turn on the electric fuel pump, until I fixed the fuel line connections,
The most common cause for leaks is the use of werm drive hose clamps, we use .032 safety wire raped twice around the tube and than twisted with a safety wire pliers than cut the tail 3/4 inch out and bend it in half and against its self so that the sharp cut end does not cut you next time you reach in to work
On something.
Happy Flying
Mark
Sent from my iPhone