General Information Maserati MK-I System

Metering Unit Oil Type:
The first type of Metering Unit on the Maserati was an Oil Type. This type used oil from the engine to lubricate the Sleeve and Rotor. On the Metering Unit there is a extra oil pump (see picture). It is very important that the oil pressure is more than the fuel pressure!! If not, petrol is fed back (with the oil) to the engine with all the resulting consequenses.
For all systems the fuel pressure must not be lower then 110 lbs or 7.1 Bar. So, the oil pressure of the Oil Pump must be higher then the fuel pressure!! Therefore it is very important that the Oil Pressure of the Metering Unit oil pump be checked every year!! And it should be adjusted on the car by a specialist.

Metering Unit Oil Less type:
This type of Metering Unit was used on the later Maserati models and has no problems whatsoever after a complete overhaul!! There is no oil pump for lubricating the Rotor Sleeve (better materials are used) and the system is, almost, identical to the Triumph MK-II type, only bigger!!