| Re: OIL STREAMING LEFT REAR OF ENGINE |
Subject: Re: OIL STREAMING LEFT REAR OF ENGINE by vetteoz on 2010/6/12 3:46:22 BeachBum wrote:Quote: What surprised me, was that the fp relay only energizes for "exactly" 2 seconds on start-up, then turns off.....by most accounts, it should stay-on.....I know from reading others, it stays on, and the oil pressure switch is then just a back-up..... but, its not the way it works on my 85.... the Oil pressure swtich is actually the main source of power for the fuel pump..... go figure. I have two different 85 ecm's, they both work the same. Strange What you describe is correct operation for all L98 engines; the ECM primes the pump for 2 sec then switches off. When the OP switch closes @ 4psi it is supposed to power up the pump directly and at the same time the ECM sees the voltage ( from the pump line )supplied to connection at #17 showing OP is over 4psi When ECM sees that signal and the pulse from the dist the ECM then runs the relay. As you note the OP switch is supposed to enable you to start ( with extra cranking )and run the pump should the relay fail From L98 Start Sequence ECM Reaction: If the ECM sees oil pressure greater than 4 PSI and the reference pulses from the distributor, it will energize the injector drivers which will begin pulsing the injectors on for 4 ms (milliseconds) periods. The ECM will also pull in the fuel pump relay in effect paralleling it electrically with the oil pressure switch. 85 pump diagram [IMG]http://i171.photobucket.com/albums/u309/vetteoz/electrical/Pump.jpg[/IMG] |
