msd total loss Problems

[shank]

I have a MSD total loss. It was in a functioning ski and was working fine. I rebuilt the motor and put it back in and it is not running.

So i put stock ignition on to the motor and it runs fine. So the motor is fine. So i have pulled the motor and ignition out of the ski.

I have rewired all leads with solder and heat shrink wrap. I have put on a new wire pin connector to the the trigger pickups.
I have tested the resistance on the trigger pickup wires. Real good.
I have tested resistance on coil wires and they are within range.
I have wired the ignition up on the floor to the motor in the garage to track down the problem. Shown in the attached picture.
I have also sent my switch settings in a picture. The switches have not been changed since it was last was working
I have checked my trigger pickup distance to flywheel and it about 0.7mm. All good
I have checked my timing its set to 29-30 degress hard to be totally exact. This was how it was previously set.
I have the MSD in LED mode and the trigger lights are coming on for each cylinder.
I have verified my coils are connected to the correct cylinder. Checking TDC of piston to MSD channel (brown or yellow) being triggered. So my spark leads are correctly wired.
I put MSD in ignition mode and hold a spark plug in the lead to motor block and the move flywheel over each trigger and getting spark down both coils and plugs spark is jumping to the block. So i got spark. I can spin it back and forth over each trigger and observe multiple sparks coming out.

i pour a little fuel down each carb and it should fire up for a second or two and then stall. But it backfires and stalls every time i try to start it. Here is a video

https://drive.google.com/file/d/1L676COue8ZT2lJCP9rieSIcLPsDH-Tve/view?usp=sharing

When the motor was inside the boat and wired up to a fuel tank. It was behaving the same as my garage floor test.

I bought a second had MSD off a guy which i was going to use as spare parts including swapping the brain out. But alas he sold me a broken ignition. The brain LED does not even come on and if the LED is broken i tested setting a trigger off which should send volts to the coils but my multimeter showed 0 volts being sent to coil so it is nuked. He says i broke it. All i didi was get it connect it to power to see if it worked and got nothing out of it. Cant do much about that.

Anyone got any ideas ?

 

[shank]

Update.

As i mentioned i bought another MSD system but the brain was broken. The coils are good though. I know this using the same tests i used above. So i put the second set of coild in use and i get the same backfire as in the video i submitted. So i dont think it is a coil issue.

Is the MSD brain water proof ? does anyone one know i assumed so as they say just to mount it onto a plate not in a ebox. Its a moulded body surrounded by aluminium. I guess water could only get in via the cables coming out i am assuming the cables are coming out of the moulded body though and water proof. is this correct ?

 

[Jcary85]

Coil A and B mixed up? Maybe try switching them?

 

[shank]

Yeh they are not mixed up. I checked each coil fire to piston position TDC.

 

[Jcary85]

Maybe just triple check or just swap plug wires and try real quick. It sounds an awful lot like mine sounded when I had wires accidentally swapped once.

 

[Harbor]

If swapping the plugs wires doesn’t help Try putting a timing light on it and check your electronic timing manually

 

[shank]

If swapping the plugs wires doesn’t help Try putting a timing light on it and check your electronic timing manually

OK i got a timing light. Works on my car. Last time i tried to use it on jet skis it didn't work. No idea why i will check it out.

So i assume i use the light on the flywheel with its cover off. Do i look for tdc or advance on the flywheel with the light. I would normally liquid paper mark TDC on a car harmonic balancer where the timing mark is never done it on a ski.

 

[iQRTurbo]

As stated earlier, it totally sounds like it is 180 off. I’m sure you have checked and rechecked but I have seen that many times and my money is also on plug wires swapped

 

[Harbor]

OK i got a timing light. Works on my car. Last time i tried to use it on jet skis it didn't work. No idea why i will check it out.

So i assume i use the light on the flywheel with its cover off. Do i look for tdc or advance on the flywheel with the light. I would normally liquid paper mark TDC on a car harmonic balancer where the timing mark is never done it on a ski.

I’d try swapping the plug wires like it’s been mentioned already first....^^^^ that’s easy..

My timing light has a 2 & 4 cycle setting.. I suppose some lights don’t and that could be an issue ????

We cut an old timing covers top off so the flywheel can be seen and still support the bendix gear..... some MSD flywheels have timing dimples near the gear, about 10 of them... each is 5 degrees.... roughly 10 flywheel teeth is about 45 degrees in either direction... see pic, dimples at the top...next find TDC of your front cylinders position, when it’s at TDC, Mark your flywheel with paint/Whitt out. Make a timing pointer from a wire coat hanger and attached to a flywheel cover bolt and bend it into a U so it’s pointing and very near to your zero mark you made earlier...... with a correctly working timing light you should see your painted TDC mark Within 2 flywheel teeth, roughly speaking with start retard on..... if your facing your flywheel, your painted TDC Mark should be appearing to the left of your pointer while cranking. each flywheel tooth roughly 5 deg....

Cut me some slack if I have the direction wrong, I doing this from memory....

Anyways you’ll be looking for something way outside of that.... I had a 62t ignitioned 701 I diag for another member and it was backfiring out the exhaust and roughly 60 deg out of time

Edit: I just remembered why my light has the 2 or 4 cycle switch.. it’s for the rpm gauge on my light.... so it has nothing to do with the flashing light..... if yours don’t flash try another timing light

Edit:: another thing, since it’s backfiring you should check your flywheel key and make sure it didn’t shear in half.... flywheel has to come off to verify it... looking up the keyway slot doesn’t work

 

[augustaf]

like this:

 

[shank]

I dont have a spare cover to cut up. I will See what i can sort out.

If it 60 degrees out. How ya fix that ?

Anyone got an answer to my msd brain being fully waterproof question ?

 

[Jcary85]

They are typically mounted exposed in the hull, not in a box. Not sure if they use the word waterproof but they can definitely get wet. They are known to fail randomly though especially in salt. I don’t think your brain is dead based on what’s it doing though.

 

[iQRTurbo]

Have you tried swapping plug wires on the coil towers yet?!? If not, just humor us and try it anyway...

 

[shank]

yeh i tried it not long ago. It backfires even worse as it shoots flame out the exhause.

I am 100% sure i got the leads right i tested again manually. Stick screwdriver down plug hole to check which cylinder is coming to TDC. Put screwdriver in lead that is connected to that cylinder and turn flywheel back and forth and get spark on lead as magnet going back and forth over the trigger. And the same trigger i check the other lead for spark and get nothing as expected.

Then i tried the same test on the other cylinder and i get same results. so leads are correct.

 

[shank]

my woodruff key is fine and the flywheel grove is as well.

 

[shank]

I manually checked the timing again. Found TDC on cylinder. Marked it on case. Switched to LED mode. Found cylinder set to 30deg. Checked the other cylinder it set to 30deg as well.

I waiting to see if my mate has a poopty old flywheel cover to chop in half for a timing light. Not sure what that gonna tell me if my manual spinning of flywheel with LED is set correct. I will try it if i can.

 

[Harbor]

I manually checked the timing again. Found TDC on cylinder. Marked it on case. Switched to LED mode. Found cylinder set to 30deg. Checked the other cylinder it set to 30deg as well.

I waiting to see if my mate has a poopty old flywheel cover to chop in half for a timing light. Not sure what that gonna tell me if my manual spinning of flywheel with LED is set correct. I will try it if i can.

By hand Your seeing the static timing, But when you shine the light during cranking you’ll see what the dynamic cranking timing is at cranking speed about 170 rpm

If it’s a timing issue, it will surely show during the test.... from their you’ll have to isolate the cause further... if your pick up plate is on correctly, you don’t see any issues and the flywheel has no mechanical damage and the woodruff key is still good.,, id Say the brain is suspect..,

Your carb needle and seats are ruled out because the engine ran ok with the other ignition system.. if they leak/pour a lot, the dumping fuel can cause a cranks no start backfire... I think you would have found this already...

 

[shank]

i kind of gave up on this. But i did get a timing light on it and cut down a flywheel cover for bendix covering only and it only lights up for the first spark when cranking starter. then now more flashes. if you let it sit for 30 secs it does the same lights up first spark. if you dont let it sit it doesnt light up at all. i couldnt even check the timing on the flywheel with the light as it does not light up enough.

This is the same if i jump the coil lead straight to the negative first spark only.

 

[iQRTurbo]

In my experience you have one of two things, bad capacitor in the brain, can’t charge up fast enough for multiple discharges and it’s junk, as they are non serviceable. Or, if you’re lucky I have seen several times where a crappy corroded fuse holder only lets enough power through for a single discharge and can’t keep up. Replacing the fuse holder made it work like new again.

 

[shank]

poop hey prob the capacitor. I figured the brain is dead. I rewired the entire thing by splicing the wires real short and soldering on new ones with heat shrink covers. I did use the same fuse box though. It dont look corroded but hey my last shot i will chop the fuse out and see if it will at least spark twice without that.