Superjet rev limiter backfiring problems

Flatdeck5

Flatdeck5

Location
South East Florida
Hey everyone I just got a superjet 650 that's bone stock for now. The ski looks great and ran great the first 2 times I took it out, but last weekend while I was riding it seemed to start hitting the rev limiter out of no where. I was on a lake so it's not like I was surf riding and hitting the limiter while in the air. Anyway it wasn't like I was in a full limp mode because I still had power and could plane and ride around just fine. So I pulled it up on shore looked at the plugs, they looked fine. Nothing caught in the prop, took it back out and ride for the rest of the day keeping an eye on the pisser, it wasn't overheating. Fast forward a few days I disabled the overheat sensor thinking it had failed and was falsely putting me in limp mode, I also deleted the fuel switch thinking maybe it was getting air in the lines. Took it to the lake started it up on land and it sounded like it was misfiring. Dropped it in the water with fresh plugs and it ran great for 30 mins.

So I thought i fixed the problem took a break for a few minutes and ride again and as soon as I got on the throttle it started doing it again where it sounds like it's hitting the limiter. I rode around for a while and hit some boat wakes and then it seemed even worse and would die if I gave it more than half throttle. So I babied it to shore and let it rest. I tried again to ride it after letting it sit and cool off and again it seemed like it was flooding itself any time I gave it gas. It would just fall on it's face.

So the overheat is disconnected, the fuel switch is deleted. I went through the ebox yesterday looking for anything suspicious, a little moisture was in the box but nothing looked bad. I unplugged everything in the box and cleaned up all connections. I cleaned the carb thoroughly and replaced the fuel filter in the carb. Ski starts up fine but sounds like it's misfiring and backfiring. Spark looks weak to me. Ski has 120/120 compression. I've disconnected start stop and it's the same. What's next? CDI? I'll take off the intake and inspect the reeds today. Should I take the flywheel cover off and inspect in there and see if the timing is off?
 
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OCD Solutions

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
The coils are notorious for broken wires so I'd start there. At the very least, remove the boots and trim back the wire some, (assuming you have the OEM screw on type of boot).
 
Flatdeck5

Flatdeck5

Location
South East Florida
jonolove said:
Compression should be 150 I'd start with two new pistons and go from there
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I know compression is low but I feel that is unrelated to what seems like a false rev limiter. I don't want to put any money into this engine I will be swapping a 701 in hopefully soon. I just am trying to figure out what is going on. I have videos of the problem where you can hear what it's doing if that helps.
 
OCD Solutions

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
I have seen them where the wire is broken every inch or so all the way back into the coil itself. Whenever I trim the wires back, I give the wire a good pull, if it's broken further in, they usually just pull right out and you know to cut deeper.
 
OCD Solutions

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
Electrical gremlins are always tricky to figure out in one single effort unless you replace everything with new or known good components.

Most often you swap a component like a CDI and the new one makes the ski run great so you think you solved it. 2 -3 rides later, it's back to acting up and you discover that the stator was on it's way out all along, the new CDI just wasn't as sensitive as the first. This is why you should mark the old components and put them on a shelf rather than toss them out. Plenty of guys have thrown away perfectly good components only to find out their stator was weak. This is also why you hear guys buying up "supposedly" bad MSD's for cheap. ;)

The service manual includes methods for static testing each component with a multimeter. The instructions are decent enough to detect flat out failed components but borderline issues like yours are nearly impossible to detect without dynamic testing.

Most guys just end up swapping parts till they get it, starting with the cheap or common stuff first.

I usually have a decent stockpile of used, refurbished or tested components and have been putting together packages for guys like you on limited budgets with little to no parts on hand. I can send you one of each component so you can go through them all until you find the culprit. Pay for only what you use and ship the rest back.
 
Flatdeck5

Flatdeck5

Location
South East Florida
OCD Solutions said:
Electrical gremlins are always tricky to figure out in one single effort unless you replace everything with new or known good components.

Most often you swap a component like a CDI and the new one makes the ski run great so you think you solved it. 2 -3 rides later, it's back to acting up and you discover that the stator was on it's way out all along, the new CDI just wasn't as sensitive as the first. This is why you should mark the old components and put them on a shelf rather than toss them out. Plenty of guys have thrown away perfectly good components only to find out their stator was weak. This is also why you hear guys buying up "supposedly" bad MSD's for cheap. ;)

The service manual includes methods for static testing each component with a multimeter. The instructions are decent enough to detect flat out failed components but borderline issues like yours are nearly impossible to detect without dynamic testing.

Most guys just end up swapping parts till they get it, starting with the cheap or common stuff first.

I usually have a decent stockpile of used, refurbished or tested components and have been putting together packages for guys like you on limited budgets with little to no parts on hand. I can send you one of each component so you can go through them all until you find the culprit. Pay for only what you use and ship the rest back.
Click to expand...

That's mighty nice of you, I may take you up on that offer. So you believe it's electrical? I have a good cdi on the way. I might test my stator and see if it's all in spec. I don't know if my backfiring and rev limiter are connected
 
Flatdeck5

Flatdeck5

Location
South East Florida
Update: pulled the reeds they look okay, worn but none chipped or broken. Had 2 coils lying around in the shop I work at so decided to try swapping that. Ski runs much better on land. Revs up much crisper with no misfiring. Won't be able to take it to the water for a bit with Christmas in a few days but hoping that the coil was just on it's way out. Fingers crossed
 
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V

Vortex

Location
Southeast
Do your stator multi meter checks with the ebox open and go from there. I had a cracked flywheel act reaaally crazy intermittent over a period of months before it finally broke in two. Changed flywheel coil and went to msd enhancer and it ran a lot better.
 
smoofers

smoofers

Rockin' the SQUARE!!!!
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Location
Granbury, TX
I had a very similar problem with the exact same symptoms. It would only rear its head after I got some water under the hood. Turned out to be the coil.
 
Flatdeck5

Flatdeck5

Location
South East Florida
smoofers said:
I had a very similar problem with the exact same symptoms. It would only rear its head after I got some water under the hood. Turned out to be the coil.
Click to expand...
Yeah it was the coil. Replaced it and it's running great now. Put About 20 gallons through it with the new coil with no issues. About to swap a 701 in it.
 
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