electrical on boat motor?
i have a 4hp mercury outboard with no fire. changed ignition coil and plug nothing...checked voltage from two wires coming from magneto and i have voltage apparently not enough. I took fly wheel off and found that there is a condenser. They want 50 dollers for this little condenser. NO WAY! so my question is...Is there another condenser (another boat motor, mower, small engine etc.) that i could use in place of this one? again it looks just like the 10 doller condensers you can buy at the lawn store, about the size of your thumb with one wire coming out of it. any suggestions? again: 4hp mercury outboard motor 1cyl, 1986. The part number on this item is mercury 336-4463 and can be found on ebay for 40-50 dollers. but if its possible to use the 10 doller one's.. well you see my logic.
I see your logic however, if you use the wrong one with a different capacitance rating you could potentially fry something MUCH more expensive.
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US $35.00
1990 Montgomery Ward 16/42 -16hp twin cyl. lawn tractor
Ignition System Trouble Shooting.
Last time we discussed how magnetic fields cause current to flow in wires. The current flow is then harnessed to make the spark plugs work.
Now we will discuss how to trouble shoot this system.
First of all the system consists of:
-A flywheel with a magnet
-A magneto with a main coil and a switching coil
-An On/Off wire
-A spark plug and spark plug wire.
That's it.
{In the olden days you had a switching circuit called points, but I will not bore you with that. I have several old motors that have points. (If you are really interested in points I will write an article about trouble shooting those...but not today.)}
So what's the problem?
The problem is that I was riding my go kart... blew the chain... made a massive clunk...engine still ran right up until I shut it off. I replaced the chain and now it won't start.
What do I do? Cry? Uh...No...
First off all look at the system. So the engine not running must be symptomatic of
-No Gas
-Flooded (too much gas)
-No compression
-No Spark
-Switch is off!
So yes, I checked.. there is gas. (check!)
The engine has nice resistance and compression (no thrown rods, no loose valves, everything is tight...) (check)
Yes I checked it was ON! Also I removed the off wire from the switch near the engine. Still nothing. (check)
Pulled the spark plug out and tested for spark:
No Spark:
The possible causes for no spark are:
Faulty Spark Plug (ie short circuiting because of ash contaiminents, broken insulator, too much gas on plug)
Or a faulty ignition mechanism
Well I cleaned the plug well. Used a different plug...
Note: But you know what I should have done first? I should have taken the plug wire and tried it against the engine. Well I tried that too: no spark.
Not looking good here... What do we do next?
This is where stuff starts coming apart.
Understand that the system involves the flywheel, so we need to access it and see if the flywheel is okay.
By "okay" I mean the following:
-Is there a magnet in it anymore?
-Did it get damaged? (very unlikely) Check with screwdriver: does it stick? (check, yes there is a magnet)
The next critical thing is to check the keyway. 8 times out of 10 the key gets sheared. This can occur from sudden stops of the engine. A sudden stop can occur from various reasons such as a broken chain grabbing hold of an activated clutch. An instantaneous shock load can be introduced into the system.
The other way an engine can be come jammed suddenly is if the rod blew inside, or the engine ran out of oil (seized up).
Next time.... What happened to the ignition system?
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