Super Jet Ground vs coil vs bad TL channel problem

[Pablo]

Looking for advice. I've got a strange ignition problem.

Fresh rebuild on Dasa 5mil coversion from SS PV engine this off season.
MSD dual channel TL
Fresh carb rebuild with clean filters, jets, and needles

Ski will start, idle, and rev fine when it's cold. After 3-5 minutes of riding my engine acts as if it's running on one channel of the ignition, or hitting the rev limiter...which I know it's not hitting limit. Rev limit is currently set at 8750. I've double checked all my grounds. Initally grounds were the main ground from starter and two additional ground from each MSD coil (negative/black grommet side of coil) to the head. The engine exhaust note is crisp and snappy initially and then changes to lower tone growl and is slow to respond to throttle input and the exhaust note is sloppy.

- I changed the coil-grounds to the couple cover bosses. The new grounds are in direct contact with the bosses...sandwiched between the coupler cover and the bosses. After this change the ski ran fine again for a few mins and then same issue. *** Should I change these again to case bolts or bundle them with the starter ground?

- I just verified fat, blue sparks from each plug (when cold). Have not done this when it's symptomatic.

Last season I had one of my channels go bad and I just moved to the spare channel and isolated the connects from the bad channel with silicone. I have two brand new MSD coils to replace the originals, but I'm getting good spark on both channels.

whatchathink?

 

[Pablo]

I just pulled my MSD TL setup out and all wiring is good to go. No breaks or frays. All connects are secure. Only thing I see is I have the blue and grey wires bundled together but capped each end with heat shrink and then covered both together with another layer of heat shrink to tuck away behind the plate. Maybe some conductance through the heat shrink??? I would think about swapping coils, but both sparks are blue and bright. All connects were gone through in off season with fresh connectors and new adhesive heat shrink and liberal di-electric grease.

 

[Waternut]

Sounds like a coil is crapping out on you... That's the typical time frame for a dying coil to last. Give it 10-15 minutes to rest and it'll run for another minute or two.

 

[Pablo]

Well, I've checked and rechecked grounds again. Verified wiring x3. Ohm tested old MSD coils and both were within spec per MSD (0.2 ohms for primary and 2000 ohms for secondary). I'm with Waternut and suspected the coils. I ran it on water till it acted up again...same scenario. I pulled it on dock and checked spark visually and it was great and with timing light it was a strong signal too, so that rules out plug wires and coils. I was still suspicious so I changed out both coils to brand new MSD coils and it ski acts exactly the same. Great initially for about 5" and then it's sloppy and bogs hard off idle when you grab a handful of throttle. When I get the prop unloaded it will clean up and act normal until I let the RPM's come down just a little bit and then it's right back to being a dog. I hate to admit it, but I'm fearing it's the brain. The whole scenario is just like when my brown channel went bad last year. Strange occurences. You guys have any insight?

I called MSD direct and they were stumped too. They were suspicious of the brain being the culprit, but I want to be sure it's not anything I can't fix before I go that route. They were confused by the fact that it cleans up when I unload the prop.

 

[McDog]

She's cursed!

 

[Waternut]

Try running ALL of the ignition grounds straight to the battery AND run the power wires directly from the battery. It sounds crazy but sometimes the places you want to use or think would be good grounds are corroded, painted, etc. and will cause poor connections. Same goes for positive connections. I struggled with grounds and power wires for an entire year back when I owned the 750. All the problems were solved when I ran everything off the battery.

Eliminate the silly uncertainties and trouble shooting gets easier...

 

[Pablo]

think bad plugs will act this way? I don't have any new plugs. I'm using my set from last year. Bad performance after they get hot?

 

[Waternut]

I've never had a plug not work when it gets hot. It either works or doesn't from my experience and I killed a lot of plugs last year from an airleak that I realized I had over the winter.

 

[Pablo]

Both the MSD techs and a few board members here have said it sounds like a dying channel on the brain. I've questioned where the problem lies though...MSD tech states that the brain/coils don't know when the load increases or decreases so the fact it comes and goes is troubling, per them. However, the only time the problem goes away is when I unload the prop and then magically it's hitting hard and crisp as long as the rpm's are up and the prop load is low. Two new coils and new wires didn't fix the problem and the airgap is within limits. The ski still starts, idles, and revs great on trailer and when cold. It will continue to run crappy when it's warmed up and under load. When it's warm and on the trailer it has great spark and revs/sounds fine???

I have a new brain now and hope to wire up next Saturday. Do u guys splice both orange wires, FROM COILS, together before u connect them to the white wire from the brain? (That's how the MSD schematic has them) The blacks, FROM COILS, will connect to either the brown, yellow, or orange channels from the pickups, correct? Of course u have to have the correct cylinders with the correct channel.

 

[Waternut]

You could disconnect one of your coils completely and the engine will sound like it's revving quickly because the one cylinder has enough grunt when it's not under load. When you're in the water, you need that second cylinder... Don't those brains have 3 channels? Couldn't you just use the two good channels?

 

[McDog]

He did that last year. If one of these channels is bad he is screwed. He already bought a new brain too.

 

[Superjetjim]

Both the MSD techs and a few board members here have said it sounds like a dying channel on the brain. I've questioned where the problem lies though...MSD tech states that the brain/coils don't know when the load increases or decreases so the fact it comes and goes is troubling, per them. However, the only time the problem goes away is when I unload the prop and then magically it's hitting hard and crisp as long as the rpm's are up and the prop load is low. Two new coils and new wires didn't fix the problem and the airgap is within limits. The ski still starts, idles, and revs great on trailer and when cold. It will continue to run crappy when it's warmed up and under load. When it's warm and on the trailer it has great spark and revs/sounds fine???

I have a new brain now and hope to wire up next Saturday. Do u guys splice both orange wires, FROM COILS, together before u connect them to the white wire from the brain? (That's how the MSD schematic has them) The blacks, FROM COILS, will connect to either the brown, yellow, or orange channels from the pickups, correct? Of course u have to have the correct cylinders with the correct channel.

Did the new Brain sort this? I have a simlar issue on an 8 month old MSD TL and so has someone else I know - seems to be a dodgey batch out there? I'm getting a yellow spark after a short while then dies altogether on both channels.

 

[wrighteous]

Any updates on this I just put on a new msd coil and now have this same issue on my TL.

 

[Pablo]

Yeah, a new brain was what the doctor ordered. Strange that one channel would die and then a few months later another channel died. It made me go through the wiring with a fine tooth comb though.

 

[JetManiac]

Yeah, a new brain was what the doctor ordered. Strange that one channel would die and then a few months later another channel died. It made me go through the wiring with a fine tooth comb though.

That sux! How old was the brain? Warranty?

 

[Pablo]

Original brain was 2 years old when I bought it. One of those risky things to buy used. I took a chance since it was a fresh water piece. It's all good now, but it was a hair pulling thing to diagnose. Summit racing is so close to us we can usually get new MSD parts on about 2 business days.