Lotus TURBO ESPRIT Service Manual page 378

Page
6 SECTION LD
The pump are permanent magnet electric motor roller-cell type, wherein the fuel
flows past the motor itself to a roller cell pump chamber.
A
motor driven disc mounted
eccentrically i n this chamber, uses rollers contained i n slots around its circumference and
thrown out by centrifugal force against the wall of the eccentric chamber, to transfer
fuel from the motor side of the chamber into the fuel feed pipeline.
1
.
Fuel Intake
4.
Pump Housing
2. Rotor Disc
5.
Fuel Outlet
The lack of an ignitable air/fuel mixture i n the pump prevents any explosion. The pump
operate whilst the engine i s cranking or running, but do not opemte i n the stalled engine
condition. The combined output
bf
both pumps i s more than the maximum requirement
6f
the engine, excess fuel being returned to the ta& via the prlmary piessure regulator. I n
order to protect the engine from damage
if
one pump fails, the engine overspeed/fuel
pump failure module senses the failure and limits maximum engine speed to approx. 2,800
rpm by cutting out the remaining pump when this speed i s reached.
The fuel pumps are also cut out i f the Overboost Switch senses too great a boost
pressure a t the inlet manifold cold start air m i l (i.e. exhaust wastegote failure).
Fuel Accumulator
The fuel accumulator i s fitted between the fuel pump and fuel
filter and is designed to maintain fuel pressure i n the system after the engine
has
been switched off i n order to aid re-&ting and vapour locks f o k f ng
.
The accum"lator also serves to deaden
any noise arising from pulsations i n the
fuel line. The accumulator'consists' of
a fuel storage chamber and spring
loaded diaphragm.
Diagram A shows the storage chamber
empty and the diaphragm pushed by its
spring against the divider plate.
1
.
Spring Chamber
5.
Storage
2. Spring
Chamber
3.
Stop (full)
6.
Baffle
4.
Diaphragm
7..
Fuel Entry
8. Fuel Exit