97 GSX no Spark

[dsteinmann]

Ok guys im working on a 97 gsx the 787. Couldn't get it to fire up when I got it yesterday. Tried a different battery, No Go. So today after work I try it and it fires right up. So cool its good to go. Power wash it stayed away from the MPEM. Fire it up After fires up runs for about a min. then it dies again. Havent got it back up. So I have no Spark now. How do I test the pick up coil or the coil itself. Don't think I had any voltage on the white wire on the coil in the rear e box (wasn't sure if it was dc or ac) Checked both but nothing really signicant if anything at all. Need a little guidance on tracing this down. Oh and I get 2 beeps! Also I don't have a second ground on the battery.

And the VTS is blowing the fuse I guess its been like that but not sure

 

[jammin777]

unscrew the spark plug boots and trim 1/4" from the wires, screw the boots back on and zip tie them and re check for spark. they tend to corrode.

 

[Mekanix]

You get ac voltage 20-60 vac and it pulses at a frequency twice the rpm your cranking.
You can test the pickup coil the same way but look for small voltages, 2-10 vac I'm guessing.
As long as its pulsing your good at the pickup.
Coils go bad inside where the wires go into It as well.

 

[dsteinmann]

Do you know what color wires off the top of your head and Should I use a test light or the digital multimeter

 

[Mekanix]

Meter !
White wire for the big coil.
Black/yellow for the small pickup coil.

 

[dsteinmann]

so black yellow to ground on DC or AC

 

[Mekanix]

AC voltage
Its actually between the black yellow and yellow/white.

The black/yellow is the ground wire and the yellow/white is the one that pulses.

So check between the two.
Just disconnect the yellow/white and measure between that and the other wire or ground.

 

[Mekanix]

Does your meter have an option for freequency ?

 

[dsteinmann]

ok I left it hooked up and probed through the wires im getting .334 volts AC while cranking

I ohmed two wires at the MPEM connector and it reads about 245 Which I belive is good.
I trimmed the spark plugs boots back also so Now I rekon its either the coil or the MPEM

 

[dsteinmann]

Yes it has a frequency option

 

[Mekanix]

Frequency is what your interested in. As long as its twice the rpm your cranking it to. It should be good

 

[dsteinmann]

OK so On the RPM Gage it says 580 - 600 When Im Cranking with the plugs out - Same thing on freq I had my girlfriend hold it while I jumped the solenoid she said 21somthing so 21xx maybe idk. But Im thinking the Pickup is good. So How do I eliminate the Digital Coil

 

[Mekanix]

if you're cranking rpm is 600 rpm the frequency should be 1200 hertz.

Only way to test the cdi is to have known good pickup and good coil. if both of those are good and the wiring is good then the CDI is the only thing left. there is no actual test for it.
It either works or doesn't.

 

[dsteinmann]

IS there a way to test the Coil? Its the model with the CDI built in to the MPEM

 

[Mekanix]

The coil you can test but only resistance.

As in: the primary side is 0.3-0.6 ohms measured between the two tabs at the bottom and the secondary side is 9-15 KILO ohms as measured between the plug caps. As long as you have that for resistances, that's all you can check except for checking if it actually fires with another cdi.

I have seen the coil go bad and the screw inside the coil where the wire screws into it had completely disintegrated.

 

[dsteinmann]

Ok the Primary side im getting 000.7 - 000.1

Ok I pulled the caps off and IM getting 12.63k Ohms So that side looks Good

 

[Mekanix]

So maybe bad caps ?

Replace them and see.

I have seen the ceramic resistor in them fall apart.

 

[dsteinmann]

So maybe bad caps ?

Replace them and see.

I have seen the ceramic resistor in them fall apart.

With out the caps I cranked it with my finger on the wire and tried it with a spark plug touching it also and I don't get anything. Wouldn't I at least feel something?

 

[dsteinmann]

I have a 951 coil but it's a single could I use that to test for spark off the mpem

 

[Mekanix]

In that coil the spark jumps from one wire to the other ans not to ground.
You would have to touch both wires to get a shock.

Im not sure how the 951 coil is wired internally but I think It would work as long as the input impedance is the same 1 ohm or less.

 

[dsteinmann]

Ok I touched both and nothing. Is there a way to see if there's anything happening on the white wire from the mpem that goes to the coil

 

[Mekanix]

Try with a test light or meter on ac volts and also check frequency.

I just realised the coil is nearly a dead short so a test light shouldn't hurt it since it is also nearly a dead short.

I think your supposed to get something like 20-30vac but I can't remember.

Also that machine might not give you any spark if the battery voltage is too low. as in below 11v