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#1
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Fuel Pump Clue requested
I have a Zenith CH-300 with a Lyc 0-320. It has an engine mounted fuel
pump, and an electric aux pump. I also have a fuel pressure gauge, and a low fuel pressure warning light. Today, for the first time, when I did my pre-flight run-up, the low fuel pressure light came on. When I looked at the fuel pressure gauge, I was showing 2 pounds, or maybe just a touch less. When I turned on the boost pump, the pressure went right back up to 6 pounds or so. In flight, with the boost pump off, the pressure shows about 3 or 4 psi. That is with partial throttle, and an rpm of maybe 2300 to 2400. If I go to full throttle, the pressure will drop to around 2 psi, and the low fuel pressure light will come on. The engine never gives any indication of being starved for fuel. But something is changing. The key question I have here, is how do fuel pumps wear out. Is a reduction in delivered pressure or volume symptomatic of the pump nearing the end of it's service life? Or maybe we have a partially blocked check valve that is leaking a bit? Does the spring inside get weak with time? And, one last question, where is a good (reasonable price) source for a pump? I have looked at Trade-A-Plane, and sticker shock is still in effect. Thanks. Zenith CH-300 Driver. |
#2
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Fuel Pump Clue requested
Hope you can solve your problem. If not you may consider another way
out. I use two electric Facet fuel pumps in my bird and no mechanical pump. 125 hrs so far and no problems with the fuel pumps for the 200HP Franklin engine. Have dual batteries - one pump on each. -------------------------------------------- http://www.abri.com/sq2000 |
#3
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Fuel Pump Clue requested
My first suspicion is that you have a pin hole in the diaphragm...
Pull the pump apart and inspect... Order parts and repair yourself... denny |
#4
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Fuel Pump Clue requested
Hi Tim. You may want to consider signing up for this email group on lycoming engines, even temporarily and ask your question: http://groups.yahoo.com/group/lycoming/ There are some very knowledgeable people on this list. Actually if you sign up, search the archives, I know your problem has been mentioned in the past. Good luck. Don. |
#5
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Fuel Pump Clue requested
Thanks, Don, Good advice. I will And Denny, If I had a pin hole, would I not have a leak somewhere? And the big question, where can I get replacement parts? Thanks. On 15 Dec 2006 09:54:57 -0800, "DonMorrisey" wrote: Hi Tim. You may want to consider signing up for this email group on lycoming engines, even temporarily and ask your question: http://groups.yahoo.com/group/lycoming/ There are some very knowledgeable people on this list. Actually if you sign up, search the archives, I know your problem has been mentioned in the past. Good luck. Don. Zenith CH-300 Driver. |
#6
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Fuel Pump Clue requested
Not necessarily... The leak can be contained and yet the pressure will
be down... There are other possibilities: worn eccentric on the cam, worn plunger rod, bad spring on the regulator, etc... But if it had been fine and suddenly the pressure turned up low it is likely something sudden such as a cracked diaphragm... Parts can be had from a number of repair shops and or vendors.. Look in Trade-A-Plane... Check on Sacramento Air Ranch, as one source of parts... The first thing is to pull the pump and have someone who speaks homebuilt aircraft help you inspect it... Usually something will be apparent... denny Tim Hickey wrote: Thanks, Don, Good advice. I will |
#7
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Fuel Pump Clue requested
Thanks Denny, Having built the machine from plans, I do speak hombuilt. And I agree with your list of potential problems. However, I will send you a beer if you can point me to a vendor who will sell me a new diaphram for the pump. I sure have not been able to find one. Do you think there might be an automotive diaphragm that would work? At this point, my money is on the inlet check valve leaking. Sometimes. At shut down, the pump seems to hold pressure between itself and the carb. I hate to replace the pump not knowing that it is the problem, but I am running out of ideas. Thanks Tim. On 18 Dec 2006 08:33:20 -0800, "Denny" wrote: Not necessarily... The leak can be contained and yet the pressure will be down... There are other possibilities: worn eccentric on the cam, worn plunger rod, bad spring on the regulator, etc... But if it had been fine and suddenly the pressure turned up low it is likely something sudden such as a cracked diaphragm... Parts can be had from a number of repair shops and or vendors.. Look in Trade-A-Plane... Check on Sacramento Air Ranch, as one source of parts... The first thing is to pull the pump and have someone who speaks homebuilt aircraft help you inspect it... Usually something will be apparent... denny Tim Hickey wrote: Thanks, Don, Good advice. I will Zenith CH-300 Driver. |
#8
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Fuel Pump Clue requested
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