Aux fuel pump revisited - aargh, what to do?

[Grant4ever]

interesting on the filters. You are only adding one additional connection since you have one connection to the header, no matter what. I looked at filters with AN fittings but I haven't decided on anything yet. Heck, I haven't even figured out what micron sizing is best!

I just like reducing the fuel line breaks in the cockpit and these filters I found were clear plastic body with sintered bronze element. I prefer metal case firewall forward.

[wapelhj]

Here's my two cents. If the engine will run without the engine pump no aux is needed. If not you have to eliminate any single point of failure and the series mounted electric pump is the answer. Some engines will not run if both pumps are running at the same time.

Filters? I remember gascolators that were just a screen and a drain for any water. My V-tail Bonanza just had a screen in the bottom of the fuel selector and that was on a fuel injected engine. KISS and buy clean fuel and skip the filters(your choice of course).

[n85ae]

Story time it is:

I remember back to test flight #4 behind my stopped IO-240B at
3000 ft. trying to decide if it was the Golf Course, or the Airport for
landing ...

I decided TWO things, (1) Having a backup pump is an excellent idea
(2) Having a BIG enough backup pump to actually run an IO-240B is an
even excellent'er idea ...

A Facet (as suppplied by Skystar) is nowhere near enough pump to run
an IO-240B

N85AE has a really expensive Weldon backup pump now, AND yes IO-240B
fuel pumps actually do fail, which means ... Yes your pump can fail also.

Been there done that

Jeff

[Av8r3400]

FYI: The mechanical pump on a Rotax 912 has a fine screen on the intake side. This is a non-servicable filter (without a ton of monkeying around).

I have no aux pump on my flying plane and never have felt the need for one.

I did add a Facet pump just down from the header tank on my project plane. The flow will go from the header to the aux pump to an inline filter to the mechanical pump then to a flow meter then to the carbs. The mechanical pump will flow through without need of bypass in the event of failure.

In our Kitfoxes gravity will flow fuel in the event of a mechanical pump failure. The pitot tubes on the fuel caps will also aid in providing a positive flow.

The main reason I added the aux pump to my project plane was to aid in cold starting. A friend has this setup and it makes the cold start (refilling the carb floats) much quicker. The process goes: turn on the pump until you hear it change pitch (float bowls full) then he shuts it off and proceeds with the engine start.

[n85ae]

Nice theory, but not true in all Kitfoxes. Certainly not mine ...

Jeff

In our Kitfoxes gravity will flow fuel in the event of a mechanical pump failure. The pitot tubes on the fuel caps will also aid in providing a positive flow.

[Av8r3400]

Being fuel injected this wouldn't apply to your IO240.

I should have qualified that statement! My bad.

[kitfox2009]

Hi guys
This may seem foolish to some but I fly a Vixen with 912UL, no fuel filters,gascolator with fine screen,use non ethenol premium marked off highway fuel except when traveling and 100ll only available.
In 600 hours I have never had a fuel starvation or contamination issue.
I replaced the fuel pump at around 400 hours. New pump with overflow drain line.
So far very satisfied with the results.
Don

[Planesmaker]

Hi guys
Beware thinking fuel will always gravity flow through a failed mechanical pump. Just had a customer have a pump failure ( new style pump only done less than 40 hrs). Fuel would not gravity feed through the pump! There was no auxiliary pump! Safe landing carried out in a paddock. Even when pump was bypassed, gravity feed was marginal on climb out, could only manage very shallow climb. This was not a kitfox but still a high wing 912 aircraft.
My advice is to have an elec backup in series with mech pump.
Tom