Tbone

Tbone

Well Known Member
I'm trying to plumb my mechanical fuel pump for a outlet fitting that includes an 1/8 npt "tee" for fuel pressure. I have ordered the 90 degree that has it hoping that it would work but the engine mount is in the way of the supply line to engine. Are there any other options that might work? A straight or 45 with 1/8 tee would work best. What have those done with their pressure pick up? RV7 superior w FI. :confused:
 
The 90 deg is the only one that has enough material volume to be able to be drilled and tapped.
What you have to do is aim the 90 down and aft, then use a slightly longer hose forming a loop upward around to the fitting.
 
I used an adjustable "Tee" fitting for mine. Maybe someone can provide the part number


(Click to enlarge)
 
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Does anyone have any pictures of their setup with fuel injection? I have the 90 degree and if there isn't any other options I would like to see how others have done it.. Thanks to those that have replied!
 
Motor mount isn't really in the way. Plenty of room to go up and over, then clamp in multiple places along the sump bolt line.

 
N941WR said:
Thanks, I don't remember having to drill and tap it but I must have.
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You don't have to drill/tap these fittings. Vans and ACS sell them with the pressure tap already machined into the fitting:

http://www.vansaircraft.com/cgi-bin...-452-282&browse=engines&product=pump-fittings

http://www.aircraftspruce.com/catalog/eppages/lycomingfitting00783.php?clickkey=12225

I recently had a discussion with Tom at TSflightlines (forum advertiser and great guy to do business with) and I think I recall him saying he had the capability to machine a pressure tap into a 45-degree fuel pump fitting. If you absolutely need this you might give him a call.

edit: what nobody has clarified yet, is that the orientation of the fuel outlet on these 90-degree fittings is adjustable. There is a nut that allows you to tighten the fitting to the fuel pump at whatever orientation you choose - the washer and o-ring can slide back and forth in a small un-threaded area of the fitting. You "loosen" the nut all the way before installing, screw the fitting into the fuel pump until you feel the o-ring start to seat and resist further movement, then loosen the fitting to your desired orientation. Hold it there with one wrench while tightening the nut with another. It will press the o-ring against the boss machined into the fuel pump. There is a torque spec for these "O-Ring Boss" (ORB) fittings in Lycoming SSP-1776-B (hard to find rev B online) that says the jam nut on #6 fittings with 9/16-18 threads gets 23-24 ft-lb torque.
 
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N941WR said:
Thanks, I don't remember having to drill and tap it but I must have.
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You probably didn't.
Van's sells the part already made.
It is included in FWF kits (along with a correct length hose to allow being installed as shown) if you bought one of those.
 
DanH said:
Motor mount isn't really in the way. Plenty of room to go up and over, then clamp in multiple places along the sump bolt line.

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Dan's routing is a good choice for an IO engine (which I failed to notice in your signature initially).
Aimed down and aft is good for a carb. because the hose has to decend so much anyway.
 
Fitting

There have been at least two Rockets that had inflight fires resulting from improper installation of this fitting or from the jam nut coming loose.
The fitting can usually be screwed into the pump until it bottoms out, then backed out for proper orientation. This should still allow the o ring to be in the area between the threads.
The AN924 nuts are available drilled. The use of a drilled/safety wired jam nut would be an excellent precaution to avoid leakeage/fire.
 
rvbuilder2002 said:
You probably didn't.
Van's sells the part already made.
It is included in FWF kits (along with a correct length hose to allow being installed as shown) if you bought one of those.
Click to expand...

It is nice to know I'm not going crazy!

The FwF kit sure made things easy and fast!
 
jrs14855 said:
There have been at least two Rockets that had inflight fires resulting from improper installation of this fitting or from the jam nut coming loose.
The fitting can usually be screwed into the pump until it bottoms out, then backed out for proper orientation. This should still allow the o ring to be in the area between the threads.
The AN924 nuts are available drilled. The use of a drilled/safety wired jam nut would be an excellent precaution to avoid leakeage/fire.
Click to expand...

Checking (eyeballs won't work, use a wrench) that the 11/16" jam nuts are tight on these fittings should be part of your condition inspection (at a minimum). It's not uncommon to find the inlet one loose due to the flexing of the hose attached to the firewall. To set the O ring in the correct position loosen the jam nut until the washer is at the far end of the O ring seating area, install the fitting until contact is made, adjust position, tighten the jam nut really tight.
 
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