Sport Jet 90 Will not plane and has no speed, HELP!

[Anders67]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Ok.

Have you check the timing .

8/10 deg/ on ideling, 30 on full wot.

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Im going to do check the timeing but i cant see that being the problem the boat fires right up and idles good and feels like theres alot of power when pushing the throttle

 

[bkhitchens]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

I can't believe no one has said anything about the stator or trigger. I have a SJ90 in a Baja. I have a bad trigger and stator. It will idle okay and will do just about anything but get up on plane. Check which stator you have and ohm check it. Do the same with your trigger. I bet you will find some significant readings.

Apparently the stator has low and high speed coils. It is not uncommon for the high side to go bad. When you go full throttle you aren't getting a hot enough spark for full power.

 

[emoney]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Don't forget too that "feels like a lot of power" is totally different than a lot of power under load. Any of these marine engines can idle
and rev fine in the driveway, but when the pressure is put on them, not so much. I still think it's safer to check off everything, starting
at the beginning, than it is to hunt and poke when you're not sure of the issue. Compression/spark/fuel. At least then you can know
for sure prior to ordering parts that are probably not returnable.

 

[aksor]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

This is the tach I have TELEFLEX #58255P, AMEGA 0-7K TACHOMETER.
Just make sure you are not waterlogged I found out that my forward bow section drain was plugged and would not empty in the bilge area and had about a foot of water maybe 150 - 200 lb of water just sitting forward of the gas tank.

 

[emoney]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Out of curiousity, how'd you end up finding the water. Although, that should help it plane instead of hurt it, I'd think.

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Ok guys here the deal. went out tonight to check the timeing and i was getting verry week and speratic light from the timeing light and could not get a reading on the flywheel that way so i took all the plugs out and the number 1 cyl is clean as new while the other two you can tell have been fireing. It just makes me crazy that the damn boat will fire and run on the number 2 and 3 cyl. I checked the trigger and got normal readings on the wires. 1258, 1199, 1252. when i first started working on the motor a few months back i cleand up all the wireing and while i was at it i check the coils and they where fine. What else could be causeing the no fire on the number 1 cyl?


BTW, Thank you verry much for the input.

 

[aksor]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Check for a cracked ferite core on the #1 ignition coil you need to remove it from its rubber case to check and check continuity of the ignition wire, if that checks out then measure for voltage between the green wire and black wire at the coil you should see ~180 vdc, if not then you have a bad scr in the switchbox. :facepalm:



emoney I found out during my tach install had to remove the panel under the dash and i could see in between the two composite stringers that water was sitting in there and it was stale smelling too.

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

I just went out and tested the stator and it tested at 695. Im thinking the trigger is bad shouldnt it test between 800-1200. Im reading 1199, 1258 and 1252 isnt that too high?

 

[aksor]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Remember temperature can play with the readings they look alright to me i would be more concerned with one reading being way lower like 500 or 400 ohms

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

yea i just found that the test should be betwen 800-1400, soo looks like the tirgger is ok. my stator tested ok at 695. ehhh maybe it could be the coil.

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

well i was out messing around with the boat trying to figure out what really was causeing all my problems and i pulled the coils off and moved them around to see if the no spark followed the coil. Well after i got everything put back togather all the plugs are fireing and the timeing at idle is at about 9 degrees. Cant do a WOT timeing test as i dont live on a lake so i guess ill be doing a test ride tomorow moring without know if the wot timeing is correct or not.

I really hope everything finaly goes my way and there wont be any more problems with the boat so i can now enjoy the rest of the season.

 

[aksor]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

yes u can, just remove the sparkplugs and ground them with a piece of wire, leave high voltage leads connected, remove throttle linkage bar from timing tower and place throttle lever into wot position then attach timing light to #1 spark wire and crank motor with the help of a helper it should be 32 degrees btdc.

Later you can recheck it while on the water and make sure it sits at 30 degrees btdc @wot

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Hmm i gues you learn something new everyday. i guess i will be doing that in the morning. Thanks Aksor

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Took boat out to the lake and got the boat up to 38mph, but she planed out really slow. all my pain and suffering was well worth it the second the boat got going.

 

[aksor]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Excellent

 

[Trailratethisfx4]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

aksor has your tach been reading correct im reading around trying to find a tachometer and the part number you listed is showing it being for a 4 stroke!

 

[Anders67]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Polish the hull with Snappy Premium Marine polish.


Do you want to go top class. Rubb hull that contacts whater with 400-600-800 (depends on top speed/speed on hull ) wet sand-paper in the lenght direction. Then put on Snappy , at least 2 layers.


This will make the whater let go, of the grip , on boat easier.

 

[aksor]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

That's the tach I have it is compatible with 4 stroke and 2 stroke engines it has a dial in the back and you set it to 6 and it works fine.

 

[silverado82481]

Re: Sport Jet 90 Will not plane and has no speed, HELP!

Ive been reading your tread and im having a similiar issue

- all plugs fire and idle
- carbs are spotless
- engine runs and idles great

so when i take off I give the boat WOT and the rpm guage goes to 6000 for like two seconds and then backs down to 4500rpm and wont go any higher IF i lean forward enuff it will eventually plane off but only do 19 to 20 knots

I tried the pulling off the sparkpug wires of while trying to plane off and 1 and 3 made a difference ( engine bogged ) while 2 did not. I was able to plane off with 1 and 3 and leaving off the 2nd cylinder plug wire off.

I swaped the coil pack and spark plug from 1 to 2 and still leaving off the plug wire of the second cylinder did not effect the motor at all still topped out 20 kontswouldnt rev ofer 4500 rpm

what finally fixed your problem jsut swaping around the coil packs around???

the motor is a 1996 95xr sport jet, the hull is a 15ft hobie jet