Engine starving for fuel

[frequent_flyer]

Still concerned if wot and fuel pump failed.

You have 2 fuel pumps don't you. As I said earlier the engine will stop if neither is working. A carb will work on 0.5 psi or less but the injection servo needs at least 20 psi.

If you are concerned about the engine driven pump you should run a test of its delivery. I don't know a standard way to do that but, unless I could find one, I'd pull the top plugs and crank the engine with the starter with fuel line disconnected at the fuel servo.

 

[BC12D-4-85]

If concerned about fuel flow and pressure install a means to monitor. Fuel pressure/flow rate gauge or warning light that illuminates below a specified pressure. And practice pushing the secondary electric boost pump on switch so it becomes a routine if the engine burps.

Gary

 

[astjp2]

This should get your attention. Can you disconnect the fuel line from the carburetor, place it in a 5 gallon gas can and fill the can in 15 minutes or less? That would be 20 gallons per hour. 1/4" for a fuel line is likely way too small. Generally you will find 3/8" as a minimum.

The Taylorcraft requires a 5/16" ID fuel lines per the STC for the bigger engine than an a-65 so I use -6 for everything and when I put on the lycoming, I am using a -8. Tim

 

[Skywalker]

I have wing tanks, but with 4 check valves(2 pumps), fuel flow sensor, screen and filter, I don't expect much pure gravity flow. I do have a pressure gauge, it predicted a slowiy plugging filter(new tanks). My FAA guy was happy with an electric-only flow test. The worksheet he used seems to require an electric pump.
The next step is to consider putting the aux in parallel with the engine pump, in case one pump fails plugged. But what if a pump fails open? Then you need external check valves. I've seen pictures of setups than must weigh 10 lbs. Haven't gone down that rabbit hole.

 

[astjp2]

I have wing tanks, but with 4 check valves(2 pumps), fuel flow sensor, screen and filter, I don't expect much pure gravity flow. I do have a pressure gauge, it predicted a slowiy plugging filter(new tanks). My FAA guy was happy with an electric-only flow test. The worksheet he used seems to require an electric pump.
The next step is to consider putting the aux in parallel with the engine pump, in case one pump fails plugged. But what if a pump fails open? Then you need external check valves. I've seen pictures of setups than must weigh 10 lbs. Haven't gone down that rabbit hole.

Way too complicated, but if that is what you want, run with it. good luck, Tim

 

[Skywalker]

It's not what I want, and I don't have it. Just pointing out that with the typical 2 pumps in series you may not get much pure gravity flow. You have to take comfort in redundancy, not the simplicity of gravity.

(most pumps have and input and output check valves built in)

 

[astjp2]

with wing tanks and a header tank, why a pump at all?

 

[frequent_flyer]

with wing tanks and a header tank, why a pump at all?

Because injected engines won't run on gravity feed.

 

[wireweinie]

It's not what I want, and I don't have it. Just pointing out that with the typical 2 pumps in series you may not get much pure gravity flow. You have to take comfort in redundancy, not the simplicity of gravity.

(most pumps have and input and output check valves built in)

Why would you put the pumps in series?

Web

 

[skywagon8a]

Why would you put the pumps in series?

Web

Both of the gear pumps in my injected Cub are in series. Both the electric and engine driven pumps have built in bypasses should there be a failure or clogging of the basic pump. There are no additional check valves as they are not needed.

 

[Skywalker]

That's a good question, Web. On carbureted engines the pumps are basically two check valves with a variable volume chamber in between. The odds of both valves failing are slim. I would just run them in parallel, the odds of a pump failing open are slim. But no one seems to do this without big honking check valves you can barely blow through.
I could tear out both pumps and go gravity, but having spotted a slowly plugging filter with a pumped and sensored system made me a fan.