1988 mercruiser 3.0 (C394105) after about an hour the motor begins to run rough and stalls. After the motor stalls it starts hard or does not restart unless it sits for 15 or so minutes.
I have confirmed that after the motor stalls or will not start the spark from the coil is not existent or erratic at best. I have swapped coils immediately after stalling and I have the same results.
I have done the following to check the fuel system even though I know this is not fuel related:
fresh fuel (non-ethanol)
new fuel lines
checked fuel vent
checked for plugged pickup
new fuel pump ( mercruiser/quicksilver)
Carb is still getting fuel after it is stalling
Note: electric choke was replaced with manual by previous owner.
Previous owner had installed a Mallory 61001m E-spark conversion kit.
I took it to a marina for this issue and they stated The module was overheating and replaced with a Mallory 6100m module. (They also replaced fuel pump at this time)
I have done the following:
Replaced factory coil with new
Replaced new coil with Mallory 29219 coil per their help line recommendation. (Internally resisted coil)
I have ran the coil with the resistor wire and with it bypassed.
I have ran the Mallory module on the coil and on its own 12v source.
Mallory module does have a circuit guard.
Through all all of these steps this problem persist. The boat starts great cold and runs great for about 30-40 minutes. It then begins to stumble, misses and will eventually stall. The boat either starts hard or does not start at all after this. After letting it sit for a while it will restart and runs good until it gets hot again.
I also noticed that When the motor begins to miss I can soak a rag in the water, put it on the distributor under where the module is located and the motor begins to quit missing within 20-30 seconds.. Take the rag off and the motor will start to miss within a minute or two.
Temp gage shows 130-140 degrees when warm. IR temp gun shows about 150 degrees on motor, distributor and coil.
Sorry for for the long winded post but I wanted to provide lots of details.
I'm confident the module is overheating and cutting out but I cannot pin point why.
Mallory suggest that it may be overheating because there should be 6-9 volts on the negative side of the coil when running, I have tried multiple coils, multiple modules 12v to coil and resisted 9.7v to coil and the the best I can get is about 4.9 volts.
Can anyone confirm this?
I'm running out of ideas and any help would be greatly appreciated!
I have confirmed that after the motor stalls or will not start the spark from the coil is not existent or erratic at best. I have swapped coils immediately after stalling and I have the same results.
I have done the following to check the fuel system even though I know this is not fuel related:
fresh fuel (non-ethanol)
new fuel lines
checked fuel vent
checked for plugged pickup
new fuel pump ( mercruiser/quicksilver)
Carb is still getting fuel after it is stalling
Note: electric choke was replaced with manual by previous owner.
Previous owner had installed a Mallory 61001m E-spark conversion kit.
I took it to a marina for this issue and they stated The module was overheating and replaced with a Mallory 6100m module. (They also replaced fuel pump at this time)
I have done the following:
Replaced factory coil with new
Replaced new coil with Mallory 29219 coil per their help line recommendation. (Internally resisted coil)
I have ran the coil with the resistor wire and with it bypassed.
I have ran the Mallory module on the coil and on its own 12v source.
Mallory module does have a circuit guard.
Through all all of these steps this problem persist. The boat starts great cold and runs great for about 30-40 minutes. It then begins to stumble, misses and will eventually stall. The boat either starts hard or does not start at all after this. After letting it sit for a while it will restart and runs good until it gets hot again.
I also noticed that When the motor begins to miss I can soak a rag in the water, put it on the distributor under where the module is located and the motor begins to quit missing within 20-30 seconds.. Take the rag off and the motor will start to miss within a minute or two.
Temp gage shows 130-140 degrees when warm. IR temp gun shows about 150 degrees on motor, distributor and coil.
Sorry for for the long winded post but I wanted to provide lots of details.
I'm confident the module is overheating and cutting out but I cannot pin point why.
Mallory suggest that it may be overheating because there should be 6-9 volts on the negative side of the coil when running, I have tried multiple coils, multiple modules 12v to coil and resisted 9.7v to coil and the the best I can get is about 4.9 volts.
Can anyone confirm this?
I'm running out of ideas and any help would be greatly appreciated!
