99’ 250hp OX66 died but started again ?
- Thread starter Ozz043
- Start date
- Joined
- Aug 13, 2014
- Messages
- 188
- Reaction score
- 12
- Points
- 18
Ok so today went reasonably well
Firstly I reconnected the kill switch wire to the starboard engine
Checked, cleaned battery terminals and lugs
Checked fuses and wires for any obvious issues
Turned fuel to opposite tank to eliminate the actual tank being an issue
She fired straight away so I ran her in gear for 3mins or so checking battery charging as she ran, then turned it off and then started again no worries put her in gear and after a minute she stopped, tried turning over no go so I swapped to battery 2, she fired up and kept going
that is odd. Then I ran her from either battery but could not get it to stall....so I let it cool.
My mate arrived and we checked plugs, compression then fired her up she ran and then stalled after @ 2 minutes what the ? It did splutter this time so we checked the VSR ... no pressure....mmm
Basically we worked out that there is an intermittent earth problem with either a wire, connector or the resistor ( which has cooling fins ). This either stops the fuel pump from run or stops the pressure switch from activating properly. The wire from the computer to the first connector is fine but from there it faults intermittently....
From there we swapped the resistor with the port engine then ran them both and couldn’t get them to stall, time for a fishing trip to see how they go...we swapped the resistor thinking that if the port engine stalls we know that it needs replacing...if starboard engine stalls we know that there is a faulty earth wire still
Fingers crossed there are no issues
Firstly I reconnected the kill switch wire to the starboard engine
Checked, cleaned battery terminals and lugs
Checked fuses and wires for any obvious issues
Turned fuel to opposite tank to eliminate the actual tank being an issue
She fired straight away so I ran her in gear for 3mins or so checking battery charging as she ran, then turned it off and then started again no worries put her in gear and after a minute she stopped, tried turning over no go so I swapped to battery 2, she fired up and kept going
that is odd. Then I ran her from either battery but could not get it to stall....so I let it cool.My mate arrived and we checked plugs, compression then fired her up she ran and then stalled after @ 2 minutes
what the ? It did splutter this time so we checked the VSR ... no pressure....mmmBasically we worked out that there is an intermittent earth problem with either a wire, connector or the resistor ( which has cooling fins ). This either stops the fuel pump from run or stops the pressure switch from activating properly. The wire from the computer to the first connector is fine but from there it faults intermittently....
From there we swapped the resistor with the port engine then ran them both and couldn’t get them to stall, time for a fishing trip to see how they go...we swapped the resistor thinking that if the port engine stalls we know that it needs replacing...if starboard engine stalls we know that there is a faulty earth wire still
Fingers crossed there are no issues
Last edited:
I had some funny stalling issues with my ‘99 225’s when I first bought the boat. The previous owner had the marina trying to troubleshoot and never got to the bottom of it. That motor ended up having a bad O2 sensor and also leaking LP fuel pumps.
The O2 sensor the engine would be all over the place in RPM and would never hold steady. The LP pumps the motor would randomly stall, usually at a lower RPM even after it was running awhile.
Many will say when you are convinced of an electrical issue on an OX66, check the fuel system again!
The O2 sensor the engine would be all over the place in RPM and would never hold steady. The LP pumps the motor would randomly stall, usually at a lower RPM even after it was running awhile.
Many will say when you are convinced of an electrical issue on an OX66, check the fuel system again!
More likely your issues were lp fuel pump related and not O2. The bad lp pumps will cause a lean starvation condition and of course the O2 sensor will detect that mixture in the combustion gasses and try to compensate but to no avail.