Bendix RSA fuel servo

I have about a 45 GPH flow rate to the servo, but only 6GPH coming out. Yellow tagged, hasn't been run, waiting for plane to be finished (ten years). I checked finger screen and it is clean.
Any guesses?

Mixture lever run both ways-------make sure it is full rich.

If you are not running it on the engine it is not sensing airflow and therefore limited fuel on the idle circuit only.

RVDan said:

If you are not running it on the engine it is not sensing airflow and therefore limited fuel on the idle circuit only.

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Yep. Squirt the throat with some compressed air from a foot or two away, and the flow rate should increase.

Why not finish airplane instead of screwing around with the servo? Unless you have a servo test setup you'll learn nothing. Bendix does advise running fuel to it when mounted to a engine that will not be run for a while. Seals can deteriorate.

RVDan said:

If you are not running it on the engine it is not sensing airflow and therefore limited fuel on the idle circuit only.

Click to expand...

DanH said:

Yep. Squirt the throat with some compressed air from a foot or two away, and the flow rate should increase.

Click to expand...

Exit path for the air flow???

This will create pressure in the intake track, but not flow. Doesn't the servo measure air flow??

DanH said:

Yep. Squirt the throat with some compressed air from a foot or two away, and the flow rate should increase.

Click to expand...

Indeed that will work, as will some leaf blowers...but...note some caution in that you don't to blow compressed air directly into the impact tubes - AND - for the flow to increase beyond the idle circuit that you are seeing now you'll need both airflow, the ability for higher fuel flow, as well as the butterfly opened up some amount (for the air to go through the body) and a reasonably accurate fuel flow instrument of some sort.

As others have stated, without a good flow bench or test rig, you don't have much to "test" here or learn other than if it is working at it's basic level or not. Wait until you start the engine, then you'll find out quickly how the idle mixture is set, how the flow is once you're off the idle circuit, etc.. Not easy to do on the bench without more specific tools.

Just my 2 cents as usual.

Cheers,
Stein

Solved

RV Dan and Dan Horton nailed it. Without engine running, that is all the fuel you will get out of it(I spoke with a overhaul shop). Plane is finished, getting ready to start it and awaiting inspection. Picture of it is in RV4 area in "status" section.

If you are really concerned about it, send it down to Don at Airflow Performance in SC, he's the fuel injection guru and can tell you everything you need to know about yours, will do a complete test for a reasonable price and provide a flow chart as well.

I sent him my complete fuel system (RSA-5) from the servo to the injectors for overhaul, my Lycoming as never started easier or run smoother (hot or cold) than it does now, I am very pleased with their work.

All the best,
Reggie

Ran the engine the other day and it fired up flawlessly. I later did a full power run up and the fuel meter was showing 17gph... can't wait to fly it.

Sounds about right for fuel flow

My -6A, with O360 and fuel injection flows about 17.5-17.8 at takeoff -- WOT, full rich, sea level, and 2700rpm.