Motorcycle Repair: Bike wont start, engine vacuum, signal generators

Question
QUESTION: Dear Wayne,

I have a 1989 Suzuki GS500E. It always starts first turn of the key in winter here, with about half choke. I fitted new spark plugs about 3 - 4 weeks ago.

Today I started it up as usual - no problem. After a few seconds I turned off the choke and gave it some high revs - not full though. Suddenly it stopped. Now it won't start - it is not firing at all.

I took out the spark plugs to see if they were flooded, but they were both okay. I tried to start it agian but to no avail. I left it for 2 hours and tried again, but still it turns over, but will not fire. Can you please help me?

Knd regards,
Dennis

ANSWER: Hi Dennis,

First thing to do is check if you have an ignition or fuel problem.
Put a spare plug in one of the plug wires, lay it on the engine and see if it
sparks when you crank the engine.

If you have spark on both plug wires then you can move on to the fuel
system most likely.

Check if the bike will fire on some carb cleaner spray or a small spray of
starting fluid (if it has spark) This will determine if the bike is getting
fuel or not.
You could have a bad fuel valve on the fuel tank.
The fuel valve uses engine vacuum to open the valve.

If you have no sparks then that will be your first priority.
Check if the orange/white coil wire is getting 12 volts from
the battery when the ignition is on as it should.
Could have a bad ignition switch or engine kill switch.

If the coils have power then it might be a faulty connection
on the ignitor unit, try cleaning the connector.
It is rare for any double ignition components to fail
at the same time like the signal generators (pulse coils.)

It will help if you can determine if the spark is working
and then if so try some starting fluid in the back of the carb
to see if it will fire. Keep the battery up and terminals tight.

Get back to me if you need to.

WS
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---------- FOLLOW-UP ----------

QUESTION: Hi again Wayne,

Please excuse my ignorance, but when you say "Check if the bike will fire on some carb cleaner spray or a small spray of starting fluid(if it has spark) This will determine if the bike is getting fuel or not," did you mean for me to spray it directly on the spark plug that I am to lay on the engine?

Also I forgot to mention that when this happened, I actually had the seat off because I had tightened up a loose screw on the grab rail. I did look around the wires, is it possible that I could have accidentally loosened or dislodged a wire somewhere?

Kind regards,
Dennis

Answer
Hi Dennis,

The spark plug laying or grounding on the engine is just a spark test.
Don't spray fuel on it as that could be dangerous.

You spray the carb spray or starting fluid into the rear of the carburetors
or maybe into the air cleaner box. If the bike has spark to the plugs
then it should fire on the carb spray even if your fuel system
is not working. This tells you that the bike will run if you get
fuel to it. This eliminates a spark problem so you can focus
on the fuel. The engine will suck the fuel in and fire if there is spark.

If you have no spark then forget about the fuel spray test
as the spark or ignition system has to be checked first.

Check the wires under the seat and also check your fuses
if there is no spark to the plugs. Make sure the engine
stop or kill switch is in the correct position as well.
People have been known to forget about that switch
as simple as it sounds.

The orange/white coil wires must have battery voltage
so if a wire ot fuse blew then they may not be getting any power.

Let me know if this is clear or you need more details.

Wayne S
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