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Fuel Pump Fitting orientation

I am in the process of installing a factory reman IO-470N in my Deb and ran into an issue with my alternator. I have a Plane Power belt driven alternator and one of the fuel pump fittings (fuel return) is pointing nearly in line with the bottom leg of the belt, causing significant interference when I install the hose. My understanding is that the fitting orientation is defined by the last couple of characters of the fuel pump part number; and with the way they’re sealed, it’s not as simple as just reclocking them as necessary.

Is it possible that I need a different part number pump to get a different fitting orientation?

Model: Debonair 35-33
Aircraft Serial Number: CD-120
Posted 10/17/2023 - 4 months ago
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This is not uncommon, different engine, different alternator. Yes, the last few digits of the pump part number reflect fitting part numbers, actual orientation can be adjusted somewhat.

Pictures might help, but how many degrees are you going to need to rotate the fitting, clockwise or counter clockwise, what is the fitting's purpose (thread size)?

Mike
ABS Technical Advisor

Posted 10/17/2023 - 4 months ago
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If I had to guess (from my pictures, I'm not at my engine at the moment), I think it probably needs to rotate 45-50 degrees clockwise. I attached a couple of pictures below, note that the shroud is crooked on the old pump picture- so make sure you look at the fitting relative to the body, not the shroud. It's a -4 line, return fuel to the LH tank.

IMG_0932.jpg - 2 MB

IMG_0936.jpg - 1.9 MB

IMG_0937.jpg - 2 MB

Posted 10/17/2023 - 4 months ago
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I'm not seeing more than 15 - 20 degree CW needed, then use a hose with a 45° fitting on the pump. It is acceptable to route the hose 'through' the belt, just maintain at least an inch clearance to the belt, and probably 3/4" to the drive pulley. Check the NPT size, likely 1/8, but may be 1/4, and put a torque wrench on it and measure breakaway torque (loosening), and compare to CMI torque chart for that fitting type. You may be able to get by with a torque up to the max value to get that 15 - 20 degrees. Use a calibrated torque wrench, and be sure to account for any torque adapter off-set. Are you an A&P, Nicholas? If not, be sure and confer with your A&P before trying this; they may have other thoughts, and have the boots on the ground to look at the bigger picture.

Mike
ABS Technical Advisor

Posted 10/17/2023 - 4 months ago
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Fuel Pump Fitting orientation