Mercury Sport Jet 90 Engine Problem need advice

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

I got the engine running and it starts with just the touch of the key .
Does anyone know why I'm experiencing vibration while going from idle to cruising speed ? Then once rpm goes up vibration goes away.

I also installed a tachometer but it reads 0 to check the voltage regulator

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

Got the tach working it turns out that whoever installed the voltage regulator tossed away the y cable harness and only hooked up the single red wire.

So I spliced the two red wires together and my battery now charges and I got a working tach.

Taking it out for a ride tomorrow to see how she goes. I also decided to call her "No Prop-lem"

Cheers

 

[Trailratethisfx4]

Re: Mercury Sport Jet 90 Engine Problem need advice

Mine also has a lil vibration dont know what it is. Im now haveing trouble finding another part. My buddy forgot to put one of the bushing pivot on the back gate for the reverse and we cant find anywhere it might have been set down. Looking all over the net i can not find one everything i come across says its no longer available. the part number i find for the part is: 23-825158, MM23825158, 825158.

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

I finally got mine out on the river with my wife and two kids started up with just a quick turn of the key we cruised around for about an hour hit 38 mph on the gps.

After slowing to idle then taking off again it started to loose power almost like a cyl was dropping so I disconnected the rev limiter and still the same issue,

I could run arround 3000 rpm but anything after you hear a weird banging noise, didn't want to do any damage so I putted home at 2000 rpm.

When I got home checked the compression all good, spark was good, replaced spark plugs with Champion from NGK starts good and idles but I got zapped by the #2cyl spark plug boot the others are fine and I also have a new clanking sound coming from either the engine bottom end or pump housing.


Any ideas anyone

Thanks

Update (the banging sound was from loosing spark at the cylinders randomly from a loose/broken capacitor lead inside the CDI unit that was randomly braking the connection from engine vibration.)

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

Well today I checked the timing and found it to be 40 btdc. I realized my stupid mistake I set the timing with the shifter control pin pulled out :facepalm:.

I reset the timing to 32 btdc and changed the oil in the gear case, but had a hell of a time getting the drain and vent screw out. I ended up busting up the vent screw and had to make a new one out of a stainless steel hex bolt. I'm gonna take it out for another spin tomorrow and see if she's ok.

 

[Trailratethisfx4]

Re: Mercury Sport Jet 90 Engine Problem need advice

I hope your next trip out has good results!

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

Just a little update

I took her out this morning to find that the engine was still missing and could not get it to rev past 3000 rpm then it quit on me tried to restart it and it kept shutting off.

Went home to find no spark once again. So i removed the CDI and opened it up to find the capacitor has failed wire broke off from all the bumping while trying to remove the potting compound, lucky for me I bought an extra one when I ordered my scr's.

BTW I was so busy trying to get the ignition fixed that I just realized that my impeller and wear ring are brand new.

Long story short I went back out this afternoon and finished of 1/2 of gas runs like a dream lots of power and averaged 36 mph on the gps.

I'm very happy to finally put my issues aside and enjoy it till next time.

 

[emoney]

Re: Mercury Sport Jet 90 Engine Problem need advice

Good for you, Aksor. I've watched this thread (and your frustration level, lol) from the beginning but never had advice, bad
or good, to share. It's great to hear that you perservered and whipped this puppy into submission. Have a great summer now
and I hope you only need to add gas from this point forward.

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

Well the good thing about this whole ordeal is that I know my boat inside out.

I have the wiring diagram memorized, I can take the entire wiring apart and fix anything I can now take my CDI apart and repair it, and if it ever breaks again all I have to do is cut the silicone seal around the perimeter and get access to the circuit board. I know how to adjust the carbs, adjust the timing.

So far I have 40 miles on the boat. Now its time to re-doo the upholstery and give the trailer a bit of a fresh paint job and enjoy the season.

 

[jbjennings]

Re: Mercury Sport Jet 90 Engine Problem need advice

Just read your thread today. Very entertaining. I'm impressed that you are able to take apart a CDI box and fix it for $6!!! You must have quite a mechanical resume---I wouldn't have any idea how a CDI box works. I'm glad you got that thing running. SOunds like you have a super nice rig for $400!!!! Ji've had similar problems with a pair of 22 year old jetski's but like you, finally got them running good and it sure feels good to be done with them!
GOod luck,
JBJ

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

Thanks for reading guys!

As for my resume I'm an electronics technician by trade so there is not much I can't fix. Fixing everything else is a hobby, I like to tinker and I never buy anything new.

My mechanical experience comes from watching my grandpa who was a jack of all trades and my oldman now retired automotive mechanic.

 

[Anders67]

Re: Mercury Sport Jet 90 Engine Problem need advice

Thanks for reading guys!

As for my resume I'm an electronics technician by trade so there is not much I can't fix. Fixing everything else is a hobby, I like to tinker and I never buy anything new.

My mechanical experience comes from watching my grandpa who was a jack of all trades and my oldman now retired automotive mechanic.

Hi again. Have a strange problem now on mine, if you can think of something causing it. Works fine but it seems to kill CDM modules.

New red stator originally
New trigger originally
New reticifer CDI

Put 4 new CDI CDM modules on 2 month ago. First one stone dead after a while, then another dead on low rpm works on high, now a third stone dead.

Is it something other, that can kill the modules??. In the paper with the modules the only thing i see, is that the kill switch shall not be over 2 volt.

A little strange.

The engine runs fine now over all. But then suddenly one CDM can die.

Anyone that have any ideas.


Regards Anders

 

[emoney]

Re: Mercury Sport Jet 90 Engine Problem need advice

Anders, i don't have any help, but I would say you're probably better off emailing CDI
and asking those guys. I'd be willing to bet they've been through this before.

 

[Anders67]

Re: Mercury Sport Jet 90 Engine Problem need advice

Try there and see what they come up with.


Thank?s

 

[Trailratethisfx4]

Re: Mercury Sport Jet 90 Engine Problem need advice

did you figure out what your vibration problem, cant seem to figure mine out!

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

Mine only vibrates for a very narrow rpm range so im not concerned.

Today was a hot one so loaded up the family and headed for the river we run for 3 hours wot pulling the tube and used up a quater tank of gas sweet I love it she runs good starts good restarts good I'm a happy camper and so are the kids their first time ever tubing.

 

[hypersniper]

Re: Mercury Sport Jet 90 Engine Problem need advice

glad to see you actually got to go out and enjoy your boat for a change. i too had a good day and got 1 of them running great. starts great runs great plans right up easily and restarts great.

 

[emoney]

Re: Mercury Sport Jet 90 Engine Problem need advice

Great news Askor. Almost makes all the headaches worthwhile, doesn't it?

 

[aksor]

Re: Mercury Sport Jet 90 Engine Problem need advice

It shure does

 

[Trailratethisfx4]

Re: Mercury Sport Jet 90 Engine Problem need advice

Sounds like it was a good weekend for everyone i also got mine figured out and took it out on sunday morning with some friends. came out of the canals from the launch and made my way to the lake when i got out to the lake i pushed the throttle down, took some time to plane out but once the boat got going and hit 38mph with me 200+lbs and my buddy 200+lbs we i started yelling for joy, one of my other friends was at the beach and he said he could hear us from the middle of the lake. All in all the pain and suffering from getting this boat right was worth it. Turned out to be one of the best weekends ever!