Fuel pump failure mode

[gear1]

Our RV8 has IO360M1A and a Tempest Fuel Pump #L15473. When cleaning up the aircraft yesterday after a long cross country I found a trail of gasoline dye behind the fuel pump drain tube. As a check, I pressurized the fuel system with the boost pump on the ground and no leakage was seen. Also, when pressurizing the system with the engine driven pump by cranking the engine, no discharge from the fuel pump drain was noted. The pump has accumulated 1400 flight hours since new.

Does anyone know how these pumps fail? Does the diaphragm slowly crack, or can the final failure be catastrophic? (I had planned to attend the 75th anniversary of my Navy Attack squadron in California this weekend but feel it would be risky to attempt the 9 hours of flight time over barren countryside.)

Any knowledge that you all might be able to provide will be appreciated.

[n82rb]

Your pump is toast. Replace before next flight. At 1400 hrs you got way more than a life out of it.

Bob burns
Rv4 n82rb

[Tim Lewis]

See minute 10 of this video from Tempest:

https://www.youtube.com/watch?v=_BfwuUjh_lA

[chrishalfman]

....but I think that's cheating!!!! Great tip! I worked at the local car garage when I was in high school. Remember fighting the pushrod on mechanical pumps. This will take all the 'fun' out of it.

[RV Jerry]

Put heavy grease on push rod ,can be done using finger , grease will help keep push rod in up position, helps to wipe as much oil off as possible, can be done without removing mag

[Larco]

Originally Posted by RV Jerry

Put heavy grease on push rod ,can be done using finger , grease will help keep push rod in up position, helps to wipe as much oil off as possible, can be done without removing mag

Spot on Jerry. and also a little grease on the gasket to help hold it in place on the pump helps too

[gear1]

Thanks all, for the great explanations, and the Tempest video. Good stuff. Now on to the replacement.....

[bullojm1]

Another trick is to use some thin safety wire to wrap around the backside of the plunger while in the UP position. Once you get the fuel pump in place and the screws started, pull the safety wire out, then tighten down the screws. Works great!

[petehowell]

+1

Wire lacing cord or a cylinder base O-ring works great here , too. Just snip and pull out.

Originally Posted by bullojm1

Another trick is to use some thin safety wire to wrap around the backside of the plunger while in the UP position. Once you get the fuel pump in place and the screws started, pull the safety wire out, then tighten down the screws. Works great!

[DanH]

The secret super sticky grease....(drum roll please): Bosch point grease, 5700-002-005.