wagoetzmann
07-08-2009, 06:48 AM
Problem Symptoms –
After several minutes of running completely normal the engine’s electrical power circuit shuts off completely.
This occurs with the ignition switch in the run position.
The boat is wired with the Mercury factory wiring harnesses.
The boat also has a separate power circuit from the battery for accessories which does not lose power when engine circuit shuts down.
The ignition switch’s purple wire feeds the gauges and gauges lights which also shut down when engine shuts down so I can easily tell when the power is on or off.
The starter (yellow/red wire) will not operate when the power shuts down.
Sometimes a couple seconds before it shuts down the engine starts to sputter just a bit.
Sometimes the engine dies and the power comes right back on.
Sometimes the engine dies and it takes several minutes before the power will come back on.
After the initial power shut down the time interval to the next shut down is shorter but the length of time the power is off is longer.
Troubleshooting –
Used DDT to verify no faults in history and performed a passing static test.
All power feeds and grounds have been verified to be good connections.
Both main power relays have been tested (92 Ohms on coils and 0.1 Ohms across closed contacts) and found to be in good condition.
Theory –
Based upon the above I believe the problem is in the ignition switch since the red wire feeds the purple which powers the main power relays, ECM and gauges.
I’m thinking after a several minutes the load on the switch causes it to heat up and have high resistance causing the red wire switch to open.
What do you guys think?
After several minutes of running completely normal the engine’s electrical power circuit shuts off completely.
This occurs with the ignition switch in the run position.
The boat is wired with the Mercury factory wiring harnesses.
The boat also has a separate power circuit from the battery for accessories which does not lose power when engine circuit shuts down.
The ignition switch’s purple wire feeds the gauges and gauges lights which also shut down when engine shuts down so I can easily tell when the power is on or off.
The starter (yellow/red wire) will not operate when the power shuts down.
Sometimes a couple seconds before it shuts down the engine starts to sputter just a bit.
Sometimes the engine dies and the power comes right back on.
Sometimes the engine dies and it takes several minutes before the power will come back on.
After the initial power shut down the time interval to the next shut down is shorter but the length of time the power is off is longer.
Troubleshooting –
Used DDT to verify no faults in history and performed a passing static test.
All power feeds and grounds have been verified to be good connections.
Both main power relays have been tested (92 Ohms on coils and 0.1 Ohms across closed contacts) and found to be in good condition.
Theory –
Based upon the above I believe the problem is in the ignition switch since the red wire feeds the purple which powers the main power relays, ECM and gauges.
I’m thinking after a several minutes the load on the switch causes it to heat up and have high resistance causing the red wire switch to open.
What do you guys think?