sport jet 90 timing problem

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boatproblem

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May 23, 2010
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I have compression tested this motor it has 135 to 140 psi on all cylinders.
the boat has good spark. what happens is when you turn it over it backfires really loud. and yes kicked the ride plate off.
now i have replaced the trigger and flywheel and the timing rod. and timed it per factory specs. i am at such a loss here, even on carb cleaner it will still not wanna start. i have also had it running in this config for a few seconds. but would it would idle up and backfire and die
thanks
 
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boatproblem

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Re: sport jet 90 timing problem

We took the boat out today, and this is what we found. We removed the flywheel again, and looked at the old trigger and compared it with the new one. The wire colors are the same colors, but located in a different configuration with the old one. We attempted to at least connect the wired to the corresponding side of the trigger and we started it and, it fired and idled. Got excited and went to the lake. The boat will fire and idle in the water. But any throttle at all and it would die. We did not bring the timing light with us, but played with the timing and retarded it as far as it could go and showed no change. We checked the coil wires with the wiring diagram and they are hooked up correctly as 1-2-3. My main question now lies in the trigger, with the wires in different locations. Does it matter for the wires to be the same top and bottom (looking down on the trigger) as to left to right on the trigger, or is it only left side right side, needs to be color coordinated? I am going to check timing again, and I read that someone had marked TDC marks on the flywheel for all the 3 cylinders. and checked timing on all the 3. So that is my next step as of now. Also when the boat was in the water it sometimes would fire backwards, which tell me timing. Thanks for you time.
 
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boatproblem

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Re: sport jet 90 timing problem

timing check update. After matching the wires exactly to the old trigger, the brown wire and the white wire were reverse on the new trigger. set the tdc on all 3 cylinders. coil #3 is timed with cylinder number one. coil #2 was not in time, but close to cylinder number 2, and coil #1 was timed in between cylinder 2 and 3. I am lost as to what to do. I honestly believe my problems lie in the wiring of this trigger. Can anyone supply a diagram as to what each color wire is supposed to do?
 
kend301

kend301

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Re: sport jet 90 timing problem

First of all please post year of engine , serial number and the part number and brand name of the trigger you installed. The wires are color coded and unless you got an aftermarket that strayed from factory wire colors. Also need to know if you have the switchbox setup or CDM setup.
We can go from there , Also be aware that timing is done at WOT . Just setting it at 8-10 deg at idle will not time it properly .
 
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boatproblem

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Re: sport jet 90 timing problem

the motor is a 94 with cdi not sure the part number on the trigger but it came from the merc dealer from the serial # on the boat. I will have to back research this to get all the part #'s I dident see any part number on the trigger.
 
kend301

kend301

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Re: sport jet 90 timing problem

I really need to know if you have a switchbox and coils or do you have a CDM conversion?
 
kend301

kend301

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Re: sport jet 90 timing problem

OK , Trigger wires are as follows , White to white , brown to brown , Purple to purple and white/black to white/black . Coil packs are as follows , Green to #1 top coil , Green/white to coil #2 middle , Green/red to coil #3 bottom. Timing is only to be done off #1 top cylinder , Must be set to 30 degrees BTDC at wide open throttle . This should put you around 8-10 degrees BTDC at idle. If you need help on how to time WOT out of the water post up and I will tell you the procedure.
 
kend301

kend301

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Re: sport jet 90 timing problem

WAIT !!! Are you running this out of the water without a flush kit hooked up ?? If so NEVER DO THAT !!! Did you get the ride plate repaired and reinstalled ????
 
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boatproblem

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Re: sport jet 90 timing problem

Ok, lets start from the beginning. Any simple problem that has been posted ANYWHERE has been tried. Please read the post in full. We blew the ride plate off already and have repaired it. We have not and will not try and start again untill it is in water. All we are doing is trying to figure out why we cannot get all the cylinders in TIME. IT IS NOT SWITCHED COIL WIRES. We believe the trigger is the issue. Please, we are not amateur mechanics. We have read the manuals for the sport jet 90 along with every post on any forum we could find on google. The questions I have in the previous posts are still valid and would like an answer to those questions. Thanks for your time.
 
kend301

kend301

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Re: sport jet 90 timing problem

boatproblem said:
We blew the ride plate off already and have repaired it. IT IS NOT SWITCHED COIL WIRES. We believe the trigger is the issue. Please, we are not amateur mechanics.
Click to expand...

Well an attitude like that gets you this ... GOOD LUCK !!! :D

PS .. I think I know exactly what is wrong with your motor .
 
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boatproblem

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Re: sport jet 90 timing problem

We have been told about blown ride plates and switched coil wires for days now on a few forums. Just stating that we have written the post in a way that if you read it. It should make sense as to what we have tried. we have narrowed it down quite a bit and are getting close
 
kend301

kend301

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Re: sport jet 90 timing problem

Post up OHM readings for the trigger . OHM readings for the Stator and also your timing reading at WOT on cyl 1
 
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boatproblem

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Re: sport jet 90 timing problem

Figured it out. We hooked in the old trigger with the correct wire configuration, and.......... everything is timed correct. at least hitting on the correct cylinders. at the correct time. Now we just need to hunt for the correct trigger. which may be a challenge, but at least we know whats wrong with it.
 
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Daremo

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Re: sport jet 90 timing problem

boatproblem said:
Figured it out. We hooked in the old trigger with the correct wire configuration, and.......... everything is timed correct. at least hitting on the correct cylinders. at the correct time. Now we just need to hunt for the correct trigger. which may be a challenge, but at least we know whats wrong with it.
Click to expand...

I bet this boat was upgraded to CDI kit that was deeply discounted about 2 years ago. I bought the same thing and it took me a while to figure out how to make it work. I had to re-use my old trigger as the new trigger wouldnt work with the old flywheel. Try looking for a trigger for the old coil style instead of CDI there is a difference.
 
kend301

kend301

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Re: sport jet 90 timing problem

kend301 said:
First of all please post year of engine , serial number and the part number and brand name of the trigger you installed.
Click to expand...

Thought I was right , proper part number for the trigger is :
Mercury : A817029A9 .. could be updated #
CDI aftermarket is : 134-7029-3

PS one more question , You posted in Chronomania's thread that you had the flywheel he needed .... Is this the flywheel that you are running on the boat ??? 859241 A 10 is for a switchbox , 859236 T 14 is for CDM conversion.
 
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boatproblem

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Re: sport jet 90 timing problem

this boat is a cdi. I have a feeling that my trigger is bad manufacture, or something. I am going to the water tomm to fire the motor with the old trigger on to see what it does. I have verified that timing is back on all 3 cylinders. this has to be the trigger.

the xr flywheel I bought 2nd hand to replace mine and when it got here it was wrong soooooooo i put in out side hoping the magnets will rust off one of these days, so i can have spares
 
kend301

kend301

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Re: sport jet 90 timing problem

Saw you posted on another thread that you had it out the other day , Glad you got her running !
 
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