FA50 - No Spark

Thanks in advance for any help. I have a 1984 Suzuki FA50, that had spark until a week or so ago, when it died on me while riding. I've checked the basics (magneto connections, fuse, battery). I have a wiring diagram, but can't for the life of me figure out how to determine where the electricity is dead ended. Any help would be great.

Also any descriptions on how to test PEI/CDI/Magneto/Rectifier/Regulator would be excellent. I have a voltmeter, just not sure how to go about testing any of these things, and what expected readings should be.

Thanks again.

Re: FA50 - No Spark

Try the simple things first, like change your spark plug. Lay the plug against the head and see what color the spark is, or if it's present. Blue/white is good, orange or yellow is crap. Then check to see if the boot or the wire leading to the spark coil has come loose. Check to see if the PEI connector is loose. Clean the contacts.

If it's still not working, test to see if the ignition is grounding out. Disconnect the PEI, turn the key and On switch on. Find the black w/red trace wire pin. See if there is continuity between that pin and the frame. If there is, the ignition is grounded somewhere and that's bad. If you find a fault, then you will systematically have to go from connector to connector, checking each wire to isolate exactly where it is occurring.

Isolate the two sides of the magneto coil. Look further down the loom from the PEI and locate the connectors for the black w/red trace & the red w/black trace. Disconnect them. Continuity between them is good, that means the coil isn't grounded out. If either connector has flow to the frame then the fault lies somewhere in those wires or at the coil itself. Leave these wires disconnected for the rest of the test.

Find the black w/red trace connector at the on/off switch. Disconnect it. Find the black w/red trace connector at the key switch. Disconnect it as well. Check from the black w/red trace pin on the PEI connector to the two switch connectors.

Test the on/off switch itself between it's wire and the handlebar. Clean the switch's internal contacts. You should only get continuity when the switch is off.

At the key switch check between the black w/red trace & the black w/white trace connectors. When the key is Off you should have continuity. In the On position, you will not.

Go back to the PEI connector. Check continuity between the black w/yellow trace pin down to the little plug that connects to the spark coil. Once again, continuity from the pin to frame is bad.

Check the Black w/white pin on the PEI connector to frame. This one you want to find continuity. If not then the PEI isn't grounded properly.

The Service Manual has a section on the proper continuity checks and ohm readings for the PEI, spark coil, and magneto. This can help determine if those specific parts are bad.

http://projectmopedmanual.info/Manuals/Suzuki/Suzuki-FA50-service-manual-1980.pdf

Also here's a wiring diagram that is color-coded. It's a bit easier to follow than the black and white one. (edited)

FA50_Wiring.png

Re: FA50 - No Spark

Jake Gosz /

Thanks a lot. I will give these things a try after work.

Re: FA50 - No Spark

Jake Gosz /

Paragraph 1: No Spark

Paragraph 2: With switch and key in On position, No Continuity from the PEI plug black /red-trace to the frame. (worked as expected)

Paragraph 3: I'm a bit confused here. Could you give the direction another way. I didn't get continuity anyway I did the test. Also I didn't know if I should be testing the male or female side of the wires.

Paragraph 4: I did not disconnect the wires at the switch or key since they were soldered, is that a problem? From the black w/red trace pin on the PEI connector to the two switch connectors in either position on/off for key and switch continuity existed. (worked as expected)

With the key in the off position I get continuity between the on/off switch in either position between it and the handlebars, no continuity with the key in the on position. (not sure what this means)

At the key switch check between the black w/red trace & the black w/white trace connectors. When the key is Off you should have continuity. In the On position, you will not. (worked as expected)

Paragraph 5: Go back to the PEI connector. Check continuity between the black w/yellow trace pin down to the little plug that connects to the spark coil. Once again, continuity from the pin to frame is bad. (Continuity exists, bad) Same result gong from the B/Y wire in the PEI to the frame (Continuity exists, bad)

Paragraph 6: Black w/white pin on the PEI connector to frame. This one you want to find continuity. If not then the PEI isn't grounded properly. (worked as expected)

Thanks again for your help, where do I go from here. Obviously some things are not as expected, but what should my next steps be?

Re: FA50 - No Spark

The important part was the first test. By checking the black w/red trace pin at the PEI plug you've determined that the entire ignition system wiring leading to the PEI is not grounding out. The next two paragraphs (3+4) was how to determine and isolate where the fault was IF you had found one.

The black w/yellow trace wire. This is the wire that conducts electricity from the PEI to the spark coil. Continuity from one end to another (from pin to tiny plug) is a good thing. That means the wire isn't broken in two. But the flow from pin to frame means it's likely frayed somewhere along it's length, grounding it out.

Tie a string to the tiny plug at the end. Carefully pull the entire length of wire up out of the frame pulling the string up with it. (The string will allow you to pull the wire back through the frame easily.) Check the wire for a worn spot. If just the insulation is worn away, cover it with several wraps of electrical tape. If you find frayed and broken strands you will need to replace the wire.

While you have the b w/y wire pulled out of the frame you could try bypassing it as a test. Make sure the PEI is plugged in. Using a spare length of wire, cram one end into the bottom part of the PEI connector so it has good contact with the base of the b w/y. Don't let it touch any of the other contacts. With the other end of your spare wire connect it to the tab on the spark coil. If the bike starts then the b w/y wire is definitely suspect and needs to be repaired or replaced.

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