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aubreypric

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I have a RV-7A with a IO-360A1B fuel injected engine. Sometime the fuel pressure will surge from 10 to 30 PSI. There doesn't seem to be any reason. Some flights it is perfect, the next time it surges. If I turn the electric pump on, the pressure goes up, but isn't stable. Is there a bypass valve in my mechanical pump that might be causing a problem. The pump is a AF 15473 Tempest. Does anyone have a manual?

Aubrey Price
[email protected]
214-725-7125
 
Which fuel injection/pump do you have? If you have airflow performance pump, there is a relief valve on top of the assembly (I think it is a blue color) which has an oring inside and time to time it may get stock and not reliving the pressure until enough pressure is build up to push it open. You can either replace the oring or take it apart to make sure it is OK. I have been told different type AVGAS (depending on the additives) could cause this oring to swell up.

Mehrdad
RV7A - IO360M1B
 
I have seen the exact same thing on a twin comanche with the IO-360's. It will just happen in cruise, last for a while and then quit. The engine does not run any different, if you didn't catch the fuel pressure surge you wouldn't know anything was going on.
 
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