Lear-Romec Fuel Pump Installation

[Birkelbach]

I've got a Romec AN style pump on my IO-320. I'm trying to figure out what all the ports are for. I get the inlet and the outlet that is pretty easy. There are four ports around the mounting flange. I'm assuming that these are for the overboard line. Basically pick the one that faces down and plug the rest, then tube it overboard to get rid of fuel if the seals start to leak.

The one that I can't figure out is the one coming out of the top cover of the pump. The pump I have has a small AN tubing fitting installed.

I'm also trying to figure out how to take a fuel pressure reading from this setup. Maybe that's what the mystery port is for?

[TS Flightlines]

Whats the part number on the pump?

Tom

[Birkelbach]

Lear Siegler RG17980A

[N54SG]

I'm pretty sure the fitting in question is a manifold pressure reference line, so the fuel pressure varies with manifold pressure. I ran a hose from my intake system through a T at the fuel pump, then up to the manifold pressure transducer. You'll need to measure fuel pressure elsewhere. I'm building a set of fittings on the pump outlet with an 1/8 NPT port to install a restriction fitting, then to the fuel pressure transducer.

[F1Boss]

If that one is like the round engine setups, those ports are leak ports if the pump shaft seal goes south in flight — the fuel gets dumped overboard and outside the cowling. Believe it or not, the same setup is on the B25 R2600 1700HP with a pump that will flow almost 400GPH.

I recall another leak port too - same thing: make sure it’s not weeping on your preflight.

On preflight - make sure the overboard line is not dripping. That’s about it.

The current NA TCM 550s use a similar design, with 2 dedicated drain ports. Most of those TCM pumps include a mixture setup, and the turbo setups have a reference line to help control the fuel flow to some degree.

The 540s use the same pump (if they have the Romec pump), as would be normal in a turbo setup. Use the AUX pump on takeoff and landing/taxi.

Call these folks to make sure of what you have:

https://www.qaa.com/products/aircraf...omec-fuel-pump

[mahlon_r]

That fitting was used on the rayjay turbo conversion of that Io-320 engine and referenced the fuel pressure setting of the fuel pump to compressor discharge or upper deck pressure. Thus keeping the fuel pump at the same relative altitude as the rest of the engine's fuel system. Since you are not turbo charged it should be vented to atmosphere.
Good Luck,
Mahlon