Installation Manual
UL
POWER
UL350i UL350i
F
UL350i
S
UL 350i
HPS
350i
SA
MI 350A01 Revision No: 7
Date:
2014-09-15
Page:
20
of
60
Fuel injection system
Accessories such as an electric fuel pump together with a pre-filter and fine fuel filter are provided
in the basic package and the fuel pressure regulator is integrated in the engine assembly. A
complete fuel connection kit can optionally be obtained from ULPower.
We would like to draw your attention to a few point before installing/connecting the fuel system:
Use appropriate fuel lines and connections as the fuel injection system requires a constant 3bar
fuel pressure.
A fuel injection system requires a return line of adequate dimensions. Large quantities
(100 litres/hour = 26 USgal/h) of fresh fuel circulate through the fuel system of which only little is
used and the remainder needs to return to the fuel tank.
We strongly encourage the use of a fuel pressure sensor and gauge to verify fuel system is
working correctly. Too much/little fuel pressure can influence the fuel mixture, possibly causing
sudden stoppage or damage to the engine as a result.
Overview
The fuel is drawn from the fuel tank, through a pre-filter (100 micron), to the suction side of the
fuel pump. From the pressure side, the fuel flows through a fine filter (15 micron), on to the
injectors which inject the right amount of fuel into the inlet manifold. The remaining fuel passes
through the pressure regulator, and returns to the fuel tank.
If the aircraft is equipped with more than one fuel tank, which are not connected together, the
return line must connect to the same fuel tank of which fuel is drawn from.
There are 2 possibilities:
install a 3 way duplex fuel selector valve which allows for 2 fuel lines to
be switched simultaneously and has the provision to return the fuel to
the same tank from which it is drawn. However never switch the
selection to the “lock” position!
install a small separate (± 2.5 / 0.7 USgal) header tank from which the
fuel is drawn and also returned, while it is gravity fed from the separate
fuel tanks. For ULP header tank, see annex A
For ease of explanation we presume the fuel system is connected to a single tank.
Attention
:
In any case, do NEVER shut of the return line from the engine to the tank! This
return line must always stay open.
Installing Pre-filter and Fuel Pump
The fuel pump (1) should be placed as close as possible to the fuel tank (3) as it is much more
powerful on the pressure side than on the suction side. The pre-filter (2) is placed between fuel
tank and pump to protect the fuel pump from being damaged by any foreign particles.
Summary of Contents for UL35Oi
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