How do I eliminate the oil pressure shut off switch? 1993 454

makomark said:

The manual will help....so would a scan tool......

A clear statement of your problem would be good too.....you inferred an issue with the starboard(?) engine's fuel delivery....won't idle, won't start, dies under load, etc?

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Certainly. And your help/interest is greatly appreciated.

SB engine stopped running when leaving marina. Restarted SB engine, turned around and docked. On another attempt days later, same scenario. On yet another (final) attempt days later, I let SB engine run/idle for several minutes while at dock and the engine stopped running. It restarted and ran for only 10-15 seconds and stopped. I have not been able to restart SB engine since then.

I have been following the electronic fuel pump diagnostics flow:
- Transmission lever in FWD, ignition held in START, does pump run? NO
- Check/reset (I replaced, just to be sure) 10-amp breaker, Transmission lever in FWD, ignition held in START, does pump run? NO
- Remove power from fuel pump, check for power with test light, Transmission lever in FWD, ignition held in START, is there power? NO
- Transmission lever in FWD, ignition held in START, check for power at 10-amp breaker on purple/red wire, is there power? NO
- Transmission lever in FWD, ignition held in START, check for power at 10-amp breaker on purple/yellow wire, is there power? NO
- Transmission lever in FWD, ignition held in START, disconnect 3-wire connector at oil-pressure switch… this is where I am and cannot find the switch in order to test/replace

Also, I have connected 12 volt power directly to the fuel pump and it ran fine. I am trying to be systematic about this. Any other routes or suggestions are appreciated.

Ok...just to complete, some of the MEFI-1/2 units will use the distributor reference pulse in lieu of the oil pressure switch to determine "engine is running" to keep fuel pump turned on.

Not sure where you got the troubleshooting details but accolades for being systematic.

I'm pretty sure you don't have the 'expensive' oil pressure safety switch.....but do believe you have a fuel pump relay.....I'd be inclined to check there first, especially given that the pump runs fine when wired direct (you should be using a fused jumper). If it turns out to be the relay, I'd suggest you change them all out, on both engines. they can be bought in bulk very economically....and there's nothing 'marine' about a relay except for its price...that said, there are some real cheap (imported) parts that wont last a season....

makomark said:

Ok...just to complete, some of the MEFI-1/2 units will use the distributor reference pulse in lieu of the oil pressure switch to determine "engine is running" to keep fuel pump turned on.

Not sure where you got the troubleshooting details but accolades for being systematic.

I'm pretty sure you don't have the 'expensive' oil pressure safety switch.....but do believe you have a fuel pump relay.....I'd be inclined to check there first, especially given that the pump runs fine when wired direct (you should be using a fused jumper). If it turns out to be the relay, I'd suggest you change them all out, on both engines. they can be bought in bulk very economically....and there's nothing 'marine' about a relay except for its price...that said, there are some real cheap (imported) parts that wont last a season....

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I think we're on to something as I located a dual ignition/fuel pump relay. The replacement is crusader ignition relay 98175 ($30/ea). I will replace both Port and SB relays. I'll report if this solved the electric fuel pump power problem.

I sure wouldn't encourage you to pay $30 a piece for the relays....if they use the 'standard' auto relay, the auto parts store would be a much better alternative.

Also, being systematic, you want to change one at a time and then check for any change....and don't forget to check the connectors in the sockets...

Problem solved! My engines have an ignition/fuel pump relay; it's one large relay that controls both. I replaced the SB relay and she rolled right over. All the help and suggestion is greatly appreciated!

Pretty work!!!

Would suggest you get one for the other side as that one will behave in a similar manner....