Any Marine mechanics out there? I have a Mercruiser question

[hsvazz]

Hi all,
I have a ski boat with a Mercruiser 5.7 Ski engine (carby) in it with a Velvet drive transmission. Just thought i'd post on here to see if any one may have a clue to my issue.

Had the boat out on the weekend, ran great all day, and then last run it started stalling. Basically you would start it, it would run for 5-15 seconds based on how much throttle was applied and then stall as if the key had been switched off.

I think it might be the oil pressure safety switch which on Mercruisers apparently determines whether the fuel pump supplies fuel. This switch gets bypassed at ignition hence fuel is delivered to the carby, but when ignition switch is in the run position it is the oil pressure switch that determines whether fuel is pumped. I'm thinking this switch could be my issue (as the oil pressure is fine, and my oil pressure warning alarm doesn't sound). My thinking is that the boat runs for 5-15 secs so that probably coincides with the fuel supplied by the pump when starting (before the oil pressure switch is engaged).

Just curious whether any of you guys work on boats or have come across a similar issue in cars also. Could a coil or points or something else cause those issues?

Regards,
Azz...

[Atomic maloo]

Float in the carby...

[vt748]

Unlikely to be a float level problem!

I think you have answered the question yourself, I would be looking at the fuel system first.

Have you bypassed the oil pressure switch to see what happens?

[hsvazz]

Unlikely to be a float level problem!

I think you have answered the question yourself, I would be looking at the fuel system first.

Have you bypassed the oil pressure switch to see what happens?

I tried to do that yesterday but not sure I did it correctly, so will try again this week.

To bypass, I presume I would just disconnect the wires leading to the oil pressure switch (purple and purple with yellow stripe) and then bridge them together, effectively sending the current front the alternator straight to the fuel pump?

Regards,
Azz...

[Blown 454 AWD]

5 - 15 sec sound like you're emptying the float chamber then stop (no fuel)

So yeah, sounds like something cutting off the fuel to the carb.

Fix = Fark that dinosaur shite, fit pump, rails and injection.

Cheers

Steve

[Atomic maloo]

My mates was doing the same thing ended up float being stuck in the carby

[hsvazz]

My mates was doing the same thing ended up float being stuck in the carby

Thanks mate i'll check that as well