So is this how a 1993 2.2 Cav Fuel system works?--any corrections/ommisssions welcomed!




1. Ignition ON ECM energises Fuel Pump Relay for 2 seconds (Fuel Pump Relay Contacts 87 to 30)

2. If engine is CRANKED or RUN ECM receives Ignition Reference Pulses and continues to energise Fuel Pump Relay until engine is switched OFF or Ignition Reference Pulses cease

3. Once Oil Pressure has built up to 2-4 PSI Oil warning light extinguishes as Oil Pressure switch contact A is disconnected from Ground.

4. Fuel Pump is also energised through now closed Oil Pressure Switch contacts C and D


Note a-- that 2 and 4 are parallel circuits to the fuel pump, therefore EITHER circuit could malfunction and the other would continue to energise the fuel pump.

Note b---Loss of Oil Pressure will NOT stop the engine, presumably until it seizes from lack of oil and the ignition reference pulses cease.


Note c---If the Fuel Pump RELAY circuit is faulty the engine should start if it is cranked long enough to build up the 2-4 PSI oil pressure and supply the fuel pump via the oil pressure switch contacts.


Note d---If the Oil Pressure Switch circuit is faulty the ECM should still energise the Fuel PumpRelay and operate the Fuel Pump

Thanks for any comments


Alont

Other than confirming the oil switch contacts (A, C, and D) you are absolutely correct.

Nice to see someone understands the circuit instead of thinking the oil pressure switch is a kill switch.

-->Slow

Thank you Slow

I just thought there was confusion on how the system worked.

I thought it would be a handy reference for anyone with fuel delivery problems

Alont