Testing Fuel Flow

[Steve A]

RV Guru's,
I have plumbed in my fuel system to my Lyc. IO 360 and tested the flow this weekend. First I took a hose from the connection just past fuel pump to a gas can, turned on my electric fuel pump. I recorded 30 gal per hour on my Grand Rapids EIS. I had a minor fuel leak which I corrected. Then I connected my hose to the mixture/throttle control body and disconnected the hose from the distribution center on top of the engine and hooked up a 1/4 aluminum tubing system to the gas can. With the electric fuel pump on and fuel running through the engine driven fuel pump, into the throttle body and then up and back down to the gas can, I only saw 6 gallons per hour on the EIS. My question is, are these values in the ball park or do I have an obstruction. I have not calibrated the EIS as to fuel flow. I assume with the engine running and pulling fuel through the system, the fuel flow will be much higher.

Sleepless in Louisiana
RV 7A finishing perpetually

 

[Ken]

Steve, I'm a carb guy so I am sure that someone will give you a better answer, but there are a lot of things that happen in the fuel servo and it is more complicated than gph flow.

There are 4 pressures involved, impact air, venturi air, inlet fuel and metered fuel. You have tested the inlet fuel with the pump but the meter fuel is controlled by the air (throttle valve). I guess this is not an answer. But this might be all you can do before you crank it up.

Ken

 

[dhall_polo]

use a watch and a calibrated bucket.

I wouldn't trust the fuel flow probe yet.

Disconnect the fuel line as it enters into the fuel servo and let the line hang into a bucket with quart markings. Then turn on the boost pump until you've filled up a quart or two and note how long it took on a stop watch. Do the math to get that to gph.

 

[David-aviator]

RV Guru's,
I have plumbed in my fuel system to my Lyc. IO 360 and tested the flow this weekend. First I took a hose from the connection just past fuel pump to a gas can, turned on my electric fuel pump. I recorded 30 gal per hour on my Grand Rapids EIS. I had a minor fuel leak which I corrected. Then I connected my hose to the mixture/throttle control body and disconnected the hose from the distribution center on top of the engine and hooked up a 1/4 aluminum tubing system to the gas can. With the electric fuel pump on and fuel running through the engine driven fuel pump, into the throttle body and then up and back down to the gas can, I only saw 6 gallons per hour on the EIS. My question is, are these values in the ball park or do I have an obstruction. I have not calibrated the EIS as to fuel flow. I assume with the engine running and pulling fuel through the system, the fuel flow will be much higher.

Sleepless in Louisiana
RV 7A finishing perpetually

With the AFP FM-200 fuel controller and the purge valve open (no fuel to flow divider) the flow rate with the throttle closed is about 1 gph, with the throttle wide open it is about 4 gallons per hour.

This all changes with the engine running and air flow through the throttle body. Your flow rate would appear near normal by AFP standards.

 

[Steve A]

Thanks for all the info, in a timely manner to boot. I will go back to my dark hangar and do some more tests. I charged up my "test" battery and will run more fuel through the system. It can't hurt and I will make absolutely sure I don't have any leaks.

S S Anderson
Lafayette, La.
RV 7A 96.5 % finished.