1996 Mercury 115 Will Not Start

[mwbailey175]

I have a 1996 Mercury 115-HP four-cylinder in-line variable displacement (2+2) two-stroke-power-cycle that will not start

I replaced the voltage regulator, but there was no change: the engine will not start

Using an in-line spark tester I observed no spark.

I added four gallons of gasoline to the fuel tank. The engine will still not start.

Give me suggestions on what further action to take to remedy the problem of the engine not starting.

My engine is the same engine that was discussed in a previous thread about poor voltage regulation.

{Moderator's note: separated from an earlier discussion about a 1996 Mercury 115-HP engine that was a four-cylinder in-line two-stroke-power-cycle engine with a unusual design in which at idle speeds only two of the four cylinders were operating, often known as the "2+2" design, and the engine problem was the engine stalled at low engine speeds.]

[jimh]

The most likely reason for the engine not starting is the absence of spark, as you have observed with the use of the in-line spark test tool.

The electrical power for spark comes from a spark coil, secondary winding.

The primary winding of a spark coil is supplied with a lower voltage, which is typically generated by a particular winding in the stator.

The control of the spark is performed by a device that Mercury often refers to as a "switchbox."

In some engines there are two separate switchboxes, with one intended for low engine speed operation, and a second intended for higher engine speed operation.

If you plan to diagnose and repair your outboard engine, you should purchase a copy of the manufacturer's factory service manual. The factory service manual will typically contain advice about diagnosing faults and making repairs that are specific to a particular engine model.

[mwbailey175]

The voltage regulator was so easy to replace that I was hoping there might be another "obvious" next step that is as easy as that.

! am not ready to jump into outboard repair with both feet. I was just looking for a quick fix. I may use 400 grit sandpaper and WD40 [to improve the electrical connection to the engine chassis].

[jimh]

For a very quick fix, be sure that the engine shut-off safety lanyard is properly installed on the engine shut-off switch. The lanyard can still be in the switch mechanism but not seated all the way. That situation will kill the spark generation.

[mwbailey175]

I'll include a check of the safety lanyard, but I'm pretty sure I checked that earlier. It's a toggle switch so I don't have to worry about being seated fully. To look again will not hurt.

[Blackduck]

I once had a 50 Mercury that would not start, I spent weeks as a young man trying to figure it out how to get the thing to start. Quite by accident I found a black wire that had become disconnected from the wiring harness termination block on the engine. After connecting, instant start. When disconnected, the engine was grounded out preventing it from starting. Sorry. I can't remember any specific details. that was 45 years ago-

[MarkCz]

You may want to try starting the motor by first disconnecting the wiring harness usually under the engine cowl that goes to the console for tilt trim starting etc. Next step would be to use a jumper wire at the engine to put 12 volts to the starter solenoid and see if the engine starts. That method eliminates problems in the key switch wiring that may be causing a no start condition. Keep in mind if it starts you won't be able to shut it off using the key and may need to use insulated pliers to pull spark plug wires until it stops.