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  #1  
Old 02-22-2018, 08:47 PM
nedricher nedricher is offline
 
Join Date: Jan 2013
Location: Peoria, AZ
Posts: 76
Default high fuel pressure

I am running an O-320. The type certificate data sheet specs the fuel pressure at .5 psi to 8 psi. It has always been in that range. Last flight it went up to 10.5 psi. Any ideas what would cause that other than a pressure sending unit. The pressure was with the engine driven pump only. With the electric pump turned on it went even higher, like around 12 psi.
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  #2  
Old 02-23-2018, 08:37 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
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Quote:
Originally Posted by nedricher View Post
I am running an O-320. The type certificate data sheet specs the fuel pressure at .5 psi to 8 psi. It has always been in that range. Last flight it went up to 10.5 psi. Any ideas what would cause that other than a pressure sending unit. The pressure was with the engine driven pump only. With the electric pump turned on it went even higher, like around 12 psi.
A bit of extra circuit resistance.
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  #3  
Old 02-23-2018, 08:58 AM
tim2542 tim2542 is offline
 
Join Date: Aug 2009
Location: Redding,Ca
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These pumps use spring pressure on the diagram to build pressure, the engine just “re-cocks” the pump. Springs don’t get stronger with age so I don’t know it can build more than design pressure. I have been told excess crank case pressure can cause an increase, and that makes sense, but I would test your pressure gauge first. If it’s a single wire design the ground path needs to be looked at, I’ve seen them mounted in an anodized fitting and that can cause problems.
Tim Andres
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  #4  
Old 02-23-2018, 09:18 AM
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airguy airguy is offline
 
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Location: Garden City, Tx
Posts: 4,368
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Gauge or wire problem is the 99.9% probability. Start by checking it with a know good analog gauge.
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Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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