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--- engine:vacuumrouting [2024/04/14 17:29]
47.128.122.104 old revision restored (2023/09/21 00:46)
+++ engine:vacuumrouting [2024/05/01 08:02] (current)
194.247.173.99 old revision restored (2024/02/21 03:25)
@@ Line 1: / Line 1: @@
 ====== Vacuum Routing ======
-Vacuum routing is slightly different between certain model years (and US/UK models). Most of this is US-centric information.
+Vacuum routing is slightly different between certain model years (and US/UK models).
+Most of this is US-centric information. This page attempts to disentangle all the vacuum lines in the engine compartment.
+The US cars had air pumps equipped for emissions compliance.
+Most owners removed this system due to the fact that it would frequently break.
+The diverter valve and the associated plumbing is usually removed. My car kept the diverter valve to make use of the vacuum connecter on the top.
+{{:engine:screen_shot_2021-12-22_at_8.49.00_pm.png?600|}}
+As explained below, the two red boxes are the vacuum solenoids for fuel pressure and ignition.
+When the solenoids are not energized:
+  * Purple and Magenta lines are connected (ignition)
+  * Blue and Cyan lines are connected (fuel pressure)
+When the solenoids are energized:
+  * Purple and Yellow lines are connected (ignition)
+  * Cyan and Green lines are connected (fuel pressure)
 ==== Vacuum Solenoids ====
-== Fuel Pressure & Ignition ==
 There are a pair of solenoids mounted under the intake plenum for fuel pressure and ignition. Lotus refers to these as part #A910E6634F.
+== Ignition ==
+Located beneath front of plenum chamber. Function is to advance ignition on operation of choke. A micro-switch operated by the dashboard end of the choke cable (which also operates the choke tell tale lamp) energises the ignition solenoid. The signal to the distributor vacuum advance capsule (normally connected to No.1 cylinder throttle
+edge drilling) is then switched to the vacuum pump, and thus full ignition advance is achieved, together with an increase in engine idle speed.
+== Fuel Pressure ==
+Located beneath rear of plenum chamber. Function is to reduce fuel pressure on 'overun' and idle. A micro-switch, mounted on the front of the front carburettor, and operated by the throttle lever in its fully closed position, energises the fuel pressure solenoid. The signal to the fuel pressure regulator (normally connected to boost pressure in the plenum chamber) is then switched to No.1 cylinder inlet manifold depression, thus reducing
+fuel pressure to the carburettors and mixture strength under closed throttle 'overun' conditions.
+== Replacement ==
 I took some time to test and investigate these solenoids (they are identical parts, but serve two different purposes).

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