What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Boost pump pressure

M

maxmirot

Well Known Member
I purchased my RV7a recently. It has a low pressure fuel system in a Lycombing 0-360. It was unused for nearly four years.

I had about 8 hours of use after purchase when the main fuel pump started reading low around 2 Psi. This was noted in flight after turning off the boost pump. Switching the boost pump back on brought it back to 4-5 PSI.
I replaced the main fuel pump it now makes a 5 psi without boost.

The boost pump makes about 2 PSI at cold start up.
This below the green arc. Is the boost pump working ok at 2 PSI or does it need to be higher at start up?

Thanks

Max
 
Most carb equipped Lycomings call for
Max 8psi, Desired 3 psi, Min 0.5 psi.
Would be great of the boost pump brought it up to 5 psi, but you are not in trouble with 2.
Also, most fuel pressure gauges aren't terribly accurate at those low pressures either.
 
I would test with a mechanical gauge first. I was dealing with very low fuel pressure readings on the RV when I purchased it. Put a mechanical gauge on it and found the sender was going bad. $35 later and I am back in the green on the gauge.
 
I have similar issues. Does the pressure line from the pump to the sender need to be bled to get the air out of the line?
 
I think my sending unit is ok because it reads 5 PSI with the new main pump.
I was wondering if I could have some air still in the boost pump line.
The boost pump has only run a few minutes after the repair.

It has been all ground testing so far.

Max
 
maxmirot said:
I think my sending unit is ok because it reads 5 PSI with the new main pump.
I was wondering if I could have some air still in the boost pump line.
The boost pump has only run a few minutes after the repair.

It has been all ground testing so far.

Max
Click to expand...

Not sure how you are plumbed, I would surmise the time you ran the engine to validate the engine pump is pushing 5PSI, you purged any air in the line. My facet pump makes a ton of noise when it cavitates. So much I can hear it over my headset.

An easy way to test on the ground if you are worried about air. Have someone drain fuel from the gascolator while you run the electric pump. Then recheck pressure.
 
You must log in or register to reply here.
Back
Top