Maserati Manual MK1
Lucas World Service News WSN604 Export
Mistral + 3500 GT Owner's Manual

FAULT C: UNEVEN IDLING, MISFIRING OR LOSS OF POWER

 Assuming there is sufficient fuel in the tank, and that the ignition/timing system is in order, a Petrol Injection fault may be revealed
during this preliminary diagnosis. An 'oily' plug indicates leaking 'O'-rings at the Metering Distributor banjo (ignition system
being in order). If this evidence is present, remove the corresponding banjo/banjo-bolt and fit replacement 'O'-rings immediately
adjacent to the bolt-thread. without such evidence, proceed directly to C.1.

TEST
C.1. Stuck Injector Nozzles

METHOD
This can take one of two forms - stuck open or stuck closed. The former is by far the most likely to be met in service, probably
due to a particle of dirt between the nozzle valve and the seat. Should the fault be a nozzle stuck closed, the idling will be very
bad, because 2 cylinders will be out of action for 4 or 8 cylinder engines, or 3 cylinders out for 6 cylinder engines. With the engine
running SHORT- CIRCUIT each sparking-plug in turn to the engine with the aid of a screw driver, and the one(s) which does not
affect the running should have the associated nozzle(s) checked. Should only ONE nozzle appear affected then it should be suspected
of being stuck open. Should TWO (4 or 8 cylinder engines), THREE (6 cylinder engines) nozzles appear affected, then one nozzle
stuck closed should be suspected.  

N.B. It is NOT possible to dismantle a P.I. nozzle for cleaning. (Old MK1 Maserati)
        (nozzles on MK2 systems can be disassembled and repaired)

ACTION
a) If the nozzles appear satisfactory, proceed toC.2.

b) Should evidence point to stuck injector nozzle(s)
    REMOVE any which appear effected. Compressed air in excess of 60 p.s.i. should clear a nozzle stuck open or ascertain a
    nozz1e stuck closed. Should this not prove conclusive, exchange any which appear affected.

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