HELP - Boat won't start - 2004 Sundeck 240 (Mercruiser)

[Alex S]

My Mercruiser MPI 50 engine turns over, but will not start. We have replaced the rotor cap and crank sensor and checked the coil. There is fuel pressure. It appears that it is only generating a yellow spark and not a nice blue spark. Any thoughts or ideas. My mechanic and I are out of ideas....all help would be appreciated! Thanks. Alex

 

[Espos4]

Pull a spark plug. Is it wet with fuel?

How about a shot of carb cleaner into the throttle body while cranking? Does it fire then?

 

[JimG]

Be sure to have your "dead man" lanyard attached.

 

[Alex S]

Pull a spark plug. Is it wet with fuel?

How about a shot of carb cleaner into the throttle body while cranking? Does it fire then?

we tried that but it did not work either. thanks for the idea.

We have not pulled a spark plug yet.

 

[Alex S]

Be sure to have your "dead man" lanyard attached.

yes we checked the kill switch at the throttle, that is not it, because we have electric and fuel pumps engaging which is not the case when the switch is in the "off" or emergency off position.

 

[Express 390]

My Mercruiser MPI 50 engine turns over, but will not start. We have replaced the rotor cap and crank sensor and checked the coil. There is fuel pressure. It appears that it is only generating a yellow spark and not a nice blue spark. Any thoughts or ideas. My mechanic and I are out of ideas....all help would be appreciated! Thanks. Alex

did it run before you changed the cap, rotor, crank sensor, etc! It might be the pickup coil

 

[dwna1a]

"Checked the coil" how? Yellow spark is a weak spark. Check the coil wire itself. How old are the batteries? Next would be the ground, is it good and clean? When was the last complete tuneup, plugs, wires? Did you replace the pickup? How old is the ICM, if you have one? IF that's bad replace the whole distributer!

If it were me I'd replace the coil, at the most they run around $35

 

[scoutaroo]

I have a similar problem with my 5.7 TBI. Turns over but no spark. Changed everything. Measured all voltages. Ignition switch w/key and safety cutout okay. Late last summer a couple of weeks after spending time on the lake, idling in driveway sputtered to a halt. Have a clamp style spark tester. No flashes. Verified operable with my car. New rotor, ignition sensor, cap, coil. Same spark plug wires, okay. Change fuel filter which doesn't effect spark. Checked connectors at ECM and cable harness connector to console. Fuel pmp runs two seconds when its turned over. No spark. The old ignition sensor was the original. New is better made with two wires and gnd. Only code 12 after changing several temp sensors. Used the paper clip method with a "beep" digital multi-meter.

 

[Espos4]

I have a similar problem with my 5.7 TBI. Turns over but no spark. Changed everything. Measured all voltages. Ignition switch w/key and safety cutout okay. Late last summer a couple of weeks after spending time on the lake, idling in driveway sputtered to a halt. Have a clamp style spark tester. No flashes. Verified operable with my car. New rotor, ignition sensor, cap, coil. Same spark plug wires, okay. Change fuel filter which doesn't effect spark. Checked connectors at ECM and cable harness connector to console. Fuel pmp runs two seconds when its turned over. No spark. The old ignition sensor was the original. New is better made with two wires and gnd. Only code 12 after changing several temp sensors. Used the paper clip method with a "beep" digital multi-meter.

Is this an alpha or bravo outdrive boat?