Engine will not start

[jacorces]

I have a 1994 Mercury 115hp outboard. The stator was recently replaced. Towards the end of the test drive the engine began having a about a 100 RPM fluctuation at speed (4500 RPM). After returning home I have not been able to start the engine again. At present I am working through the ignition system. All resistance values are in spec. All voltages are good up the the ignition coils. Voltage at the coils are around 100 volts and spec is 130 volts. I checked the spark plug spark by grounding the plug to the engine block and turning over the engine. I checked the spark at night in a dark area.The spark color was white for all plugs. Is a white spark OK??[/B] I am reading the spark should be blue.

 

[sam am I]

Re: Engine will not start

A red or yellow spark is weak, blue or white spark is stronger, so I think that's fine.........

Fire/explosion needed to get that crank shaft to move takes 3 things.....an ignition source, fuel and oxygen . Sounds like you have the ignition covered so far.

Sometimes in similar situation(less connecting rods laying on the ground, not your case sounds like), I'll pour a small amount of fuel (oil/gas mix) directly into the carbs as a quick diagnostic.

Pour a tad (tablespoon'ish) down each throat of the carbs, crank it over, if it fires/runs decent for a few sec's and dies, you know spark/timing/ignition and O2 is most likely not the issue and you have a fuel issue.

If it backfires (don't stand near/over carb's openings, you'll loose hair), coughs, spits.....timing typically is the issue but O2 and spark most likely ok though.

No fire at all......no spark (think that's working thou based on your post)

Let us know

 

[alldodge]

Re: Engine will not start

I have a 1994 Mercury 115hp outboard. The stator was recently replaced. Towards the end of the test drive the engine began having a about a 100 RPM fluctuation at speed (4500 RPM). After returning home I have not been able to start the engine again. At present I am working through the ignition system. All resistance values are in spec. All voltages are good up the the ignition coils. Voltage at the coils are around 100 volts and spec is 130 volts. I checked the spark plug spark by grounding the plug to the engine block and turning over the engine. I checked the spark at night in a dark area.The spark color was white for all plugs. Is a white spark OK??[/B] I am reading the spark should be blue.

+1 with Sam, you have spark, need to check compression and fuel

 

[out 2 launch]

Re: Engine will not start

I checked the spark plug spark by grounding the plug to the engine block and turning over the engine.

An ignition output test done in this fashion is almost useless.

Fire/explosion needed to get that crank shaft to move takes 3 things.....an ignition source, fuel and oxygen .

You might want to add "compression".

 

[Mi duckdown]

Re: Engine will not start

Check compression. that takes alot a guess work out.

 

[jacorces]

Re: Engine will not start

Many thanks for input!!!

I will begin looking in the areas mentioned.