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Fuel Pump and fuel lines

cdeerinck

cdeerinck

Well Known Member
I'm looking for any feedback on the fuel lines in this picture before making it permanent. This is for a EFII fuel injection setup. Two lines are missing from the picture. From the top of the fuel filter into the gear tower, and the return line from the firewall to the gear tower, which will be nearly straight, and next to the fuel pumps.

The side plate will be riveted via a piece of angle aluminum sheet at the bottom center. But even without that, the pump can't move.

The stud holding the filter is by Click-Bond, but I could drill into the tower, and use a bolt from inside if there is good reason to.

None of the lines are under any lateral pressure, but the fit is tight. I will be able to remove any of the lines, pumps, and filter after the final installation.

This is my first build, and I want to make sure I'm not doing anything dumb.

2z556xx.jpg
 
The painted firewall and aluminum bulkhead fitting are not good ideas.
 
Given an engine compartment fire, the aluminum bulkhead fitting will melt in seconds, but no matter, as the smoke and flame from the burning paint will have already done you in.

§ 23.1191 Firewalls.

(f) Compliance with the criteria for fireproof materials or components must be shown as follows:

(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.

(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.

(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.

(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.

§ 23.1182 Nacelle areas behind firewalls.

Components, lines, and fittings, except those subject to the provisions of §23.1351(e), located behind the engine-compartment firewall must be constructed of such materials and located at such distances from the firewall that they will not suffer damage sufficient to endanger the airplane if a portion of the engine side of the firewall is subjected to a flame temperature of not less than 2000 °F for 15 minutes.
 
If I may---I'd make the outlet line from one piece of tubing, instead of several connectors. Steel bulkhead fitting at the firewall, as per Dan's note.
WE tend to like hoses connecting at the firewall on nose gear planes---incase of gear failure, accident, or other incident that might bend the firewall, fracture a rigid tube an put fuel in the cabin. Hoses will flex 'some" and 'may' remain intact in an incident. Dont want to test it.

In some areas, like this, a hose may be too short to be used in the location you show.
Tom
 
Fuel pump

If you turn the pump 180* the outlet will be at he rear and inlet at the front, much easier to fab the fuel lines . I would also place the fuel filter under the fuel valve cover, it would be on the same level as the valve and pump , also easier to service .
 
Ok, I surrender!!! Great feedback, and I was doing many things badly.

I am scared by how many pictures of other RVs that I see with aluminum pass-thru's, aluminum fittings, and aluminum tubing right up to the firewall. Just google "RV-8 Fuel Firewall" and open the images, and you can see for yourself.

Mine would have worked as long as nothing went wrong. But that isn't good enough for me.
 
I knew instinctively that primer on the back of my SS firewall didn't make sense (previous builder) but it never occured to me that I would be breathing it in the event of a fire. Out comes the MEK.

FWIW, your firewall paint certainly looks nice:eek:

I learn here every day.
 
Question. The firewall is held on by aluminum rivets. If a fire is that intense for a significant time, wouldn't the rivets holding the firewall fail. And if all the rivets fail, your firewall falls off?
 
togaflyer said:
Question. The firewall is held on by aluminum rivets. If a fire is that intense for a significant time, wouldn't the rivets holding the firewall fail. And if all the rivets fail, your firewall falls off?
Click to expand...

No, because the steel engine mount is bolted through the firewall to the steel weldments bolted to the longerons, which are behind the stainless steel firewall. If the fire is intense enough to melt the rivets out of the firewall you'd have some little holes, but that would take a while.
 
I dont even want to think about guys having fires, much less having one hot enough to melt rivets. Scares the **** out of me.
Tom
 
cdeerinck said:
Two lines are missing from the picture. From the top of the fuel filter into the gear tower, and the return line from the firewall to the gear tower, which will be nearly straight, and next to the fuel pumps.
Click to expand...

Aside from the items that others have mentioned, isn't one of the features of the EFII pump that is does not need a return line?
 
xblueh2o said:
Aside from the items that others have mentioned, isn't one of the features of the EFII pump that is does not need a return line?
Click to expand...

None of the currently available pumps (EFii, Airflow Performance, or Andair) needs a return line if used with a Bendix-style (AFP or Precision) constant flow system. Fuel flow is one-way; all fuel passing through the pump is consumed by the engine.

Early Airflow pumps had a short external return line from the pressure regulator at the pump outlet, back to the pump inlet.

Old-school electronic injection systems (including the "EFii" brand) require a high volume return line, again regardless of pump brand. Fuel is pumped to a supply loop feeding all injectors. Pressure is maintained at a set level using a mechanical pressure regulator at the loop outlet, which sends excess fuel back to the wing tank(s).

Current automotive EFI systems regulate injector supply pressure at the in-tank pump, and do not require a return line.

Nothing conceptually wrong with any of these systems. They all work.
 
Some EFI auto stuff use a vacuum sense fuel pressure regulator to raise fuel pressure under a load and Do send return fuel to tank.......
 
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