Backup fuel pump for IO-240 engine

[n85ae]

I think any 30'ish psi pump would be good, those look like some decent pumps.
I did have the Holley Blue on mine for a while that Bruce has, but finally paid
for the Weldon. With the Weldon it is one of the easiest starting airplane engines
I have ever used. Unless it's really cold out then it's jumper cable time ...
The Odyssey back in the tail just doesn't have enough umph for really cold weather.

That Aeromotive 340 looks like a good pump to use. If I didn't have the Weldon
I might look at that. The Holley makes it start easy, but I think you'd get about
only 1/2 throttle max if you lost the engine driven pump in flight, with it as
a backup (it's about 14 psi).

Regards,
Jeff

[PapuaPilot]

Thanks everyone for your input and pictures. You all have been very helpful.

I'm a little concerned that the Holley Blue pump would be on the low side for an emergency pump because it only makes 14 psi maximum. Jeff's comment about it taking 10 psi to bypass the engine driven pump may mean that there is only 4 psi remaining the goes to the engine; this would barely get the engine above idle.

I am going to see if I can find a used 12 volt Dukes pump where I work. If not I will look into other options such as a new Weldon, CJ or Dukes pump.

I am planning on getting an aluminum tank and not even bothering with the poly tank that came with the plane.

[n85ae]

Let me clarify what I meant about the pressure:

The fuel injection system has a distribution block that has spring loaded ports. It
requires a certain amount of pressure (approx 10 psi) to get them to pop open
and allow fuel into the intake ports. With the Facet they will not really open
but basically leak fuel into the runners. This is why for example on the Diamond
Katana version of the motor, they use a modified drain on the intake runners
with a standoff to allow fuel to puddle to help with starting. Rather than simply
trickle out the drain.

On the IO-240B you want to have a LOT of pressure when you prime the
engine so it can "squirt" into the runner and splash fuel around. The excess
runs out the drains. However the splashed fuel vaporizes, and makes the
engine MUCH easier to start. Fly a Diamond with the drain solution they use
and you will fnd it is much more difficult to start than mine is.

Now in order to "run" the engine in flight, IF the engine driven pump has
failed you need a continuous amount of high pressure (30+ psi) to provide
enough fuel to run the engine at higher power settings. The pressure to
run the engine at "idle" for example requires 9.4 - 9.8 psi. With the pressure
required at 2800 rpm being somewhere around 30+ psi.

In an emergency with a fixed output pump, the engine would NOT be
regulating the pressure for you. So you would have to set the throttle
to some arbitrary position, and THEN adjust the mixture lever in and out
to adjust the pressure to where the engine would run approximately
correctly. This is assuming that the engine driven pump was not so fubar'd
that it could run at all anyway since your boost pump has to drive fuel
through the engine driven pump (the one which just failed).

Fly a Kitfox with an IO-240B and lose the engine driven pump one time in
flight, and I guarantee you will know a lot about it, just like I do "now" after
having had it happen to me.

Here's the truth about pumps on the IO-240B, I have used all three of
the below listed pumps.

1 - The Facet pump is inadequate.

2 - The Holley Blue makes enough pressure to start the engine, but could
probably NOT run the engine in flight.

3 - A 30+ psi pump makes starting a breeze, and "might" run the engine in
an emergency IF the mechanicals of the engine driven pump were not wrecked from the failure.

My pump failed, because the drive shaft seal failed, allowing the pump to suck
air and cavitate. This was part of a Critical Service Bulletin CSB-01-1 and
Teledyne replaced my pump for free after it failed EVEN though the engine
was not under warranty.

Regards,
Jeff Hays

[SkyPirate]

the problem today is finding a non EFI controlled pump,..this one doesn't list EFI control,..but a phone call would be best to confirm




http://www.summitracing.com/parts/acc-74701/overview/

[SkyPirate]

the above pump doesn't have a return line requirement..this is a plus,..a mechanical controller can be installed with a pressure gauge on the positive pressure side of the pump ( the fuel out side) I don't think it says that it is a free flow pump meaning it will or will not allow fuel to flow thru it without power,..some do some don't confirmation on that should also be asked if you order one

if a redundant fuel pump is applied to your system,..a check valve on the electric pump line between the primary fuel line and pressure gauge of redundant line so the main pump doesn't put back pressure on the electric pump,..and also on the main line between the primary pump and the connection point of the redundant pump so the electric pump doesn't put back pressure on primary pump

this set up might also require separate fuel shut off valves,..not knowing the type of mechanical pump your system uses

ok after re reading the bottom of your post if it will suck air,..it will also leak fuel if a secondary pump is installed with out a check valve

[n85ae]

You can always put a check valve in parallel to the pump if pump off flow-thru
is an issue. That's what I did with the Holley Blue pump when I was using it.

[SkyPirate]

actually ,..thinking about it,.. the pressure control valve I used had an off position,..it was a requirement in case of fire,.. one of the nascar rules for sanctioned tracks

[PapuaPilot]

Jeff, I think you are right about the Holley Blue being marginal and a 30+psi pump working. Good pressure will definitely give you better priming for starting.

The engine data sheet from Continental that came with my IO-240 shows it needs 35-53 psi of unmetered pressure for full power. During the full power run they had an actual 53.0 psi unmetered pressure that yielded 16.3 metered pressure. Unmetered pressure is what is coming out of the engine driven fuel pump, therefore I have to believe that you must have the same pressure from any backup pump (if you want full power).

I have a lot of experience working with Cessna TU-206s that have the Cont. TSIO-520. They have a 3 speed boost pump (Emergency, High and Low) that MUST be setup properly so the engine can run in case the engine driven pump fails. It uses the lower speeds with a throttle microswitch so the engine can run OK from cruise power to idle. The emergency position is incase you need full power, but you have to hold the red switch on as it is spring loaded to off. If the fuel flows are misrigged for the other two positions it can cause the engine to die because it is too rich or lean.

I looked online and think I found a Holley pump that should work great with the IO-240. The Holley model 12-920 inline pump shows specs of 67 gph @ 45 psi. It weighs 2.6 lbs. They say you must use a 40-100 micron filter before the pump (for warranty). This seems like a good idea to have the filter. I would put one at the outlet of the header tank and then tee it to a bypass valve and the Holley pump. I don't think it would need a regulator. Amazon has this pump for $176 and the filter for $64 which is a lot less then a Dukes or Weldon pump.

I like the Cessna 206 system but it is complex. There is another option. If you have enough fuel pressure for full power then you can keep flying if your engine pump fails. You would need to turn on the aux pump and open to full throttle; the engine will run. After that you can reduce power slowly (till it is getting rich/rough) and lean the mixture the engine runs smoothly again. If you do the power/mixture reduction in a few steps you can make the engine run all the way down till landing. At MAF,where I work, we used to have a standby emergency fuel pump system in our TU-206s that did exactly that. It used a second Dukes pump.

If I can't find a used (free) 12 volt pump at work I will most likely get the above mentioned Holley setup.

[n85ae]

Yep, that's exactly what I think. Continental used to have a chart that showed the unmetered pressure up to 2800 rpm, but I can't find it now. I have a couple
that show the metered pressure. The priming pressure issue, was one that a
Continental tech rep explained to me. I think if you get 30 psi or more, then
you should be able to tweak everything to make it run at least long enough
to get close to an airport.

I also found a note that the engine driven pump does have a built-in bypass for
exactly this reason.

Regards,
Jeff Hays

[N981MS]

After reading Jeff's account I went with a Weldon. Much more comforting than the Facet. It is warm enough in Georgia that I really never noticed any trouble starting with the Facet though.