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Fuel Pump Issue

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Supporting Member
Aug 5, 2008
Reaction score
Huntsville, TX

I currently have an HIO-360 with the mechanical primary fuel pump and a Christen wobble pump as a back-up. When pumping the wobble pump, I can only get 7 PSI and when testing the flow out of the injectors, only 200 ml in 60 pumps - not the 1 gallon I should (on the pump face, it says 60 GPH fuel flow @15 PSI and 60 pumps per minute). Here's some background:

- I had a clogged injector - this prompted some pre/post cleaning flow tests.
- I have no experience with the Christen pump - that's because I did not build the plane - I bought it from an estate when the owner passed away
- There are only 110 hours on the engine/airframe, but I don't know the history of the components
- I do know that the output pressure of the Christen pump is adjustable, fron 5-25 PSI, but have no idea where on the pump there is an adjustment screw or similar (I've looked)
- My efforts to find an instruction manual on the pump have been futile
- No leaks
- If I can not find a solution, I'm going with an electric (probably an Airflow Performance)

Any help?

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