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

[aksor]

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

You sure cooked that piston, bad fuel pump I assume? when was the last time you replaced your fuel pump diaphragm? It should be done yearly to be on the safe side.

What model of electric pump did you get?

Inductive resistor means its safe for CDI ignition, resistor type is supposedly bad for CDI.

Anyone else ?

 

[Anders67]

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

I changed parts in Fuel pump in May/June. New Diaph. and valves. All checked .

Solenoid electric type fuelpump 120l/h 6 psi around. Let it push to the originally one. Seems to work fine . It cost only 15-20$, so i did it to be on the safe side.

Checked the carbs again , but can not find any type of problems with them , that can cause this on the pistons. All ok there.


Well, well !. All works fine for the moment. But i?d like to have the RPM up 2-300, for a little more top speed.


Is it someone hwo have replaced the impeller?. And know if Solas make someone that fits this pump?. And if it?s give any uppgrade in tourqe ore speed?.



Thank you for the ans. on the spark plug.


http://www.ngk.com/sparkplug411.asp?kw=Inductive+resistor&mfid=1



http://www.championsparkplugs.com/charglossary.asp?kw=Resistor+plugs+for+race+engines




Inductive Resistor Spark Plugs Specified as original equipment in a variety of late-model outboard engines, spark plugs with an inductive resistor are utilized when a CDI (capacitive discharge ignition) system is used. The resistor plug is necessary to reduce radio frequency interference (RFI), to prevent interference with the sophisticated electronics onboard modern boats.
Most resistor spark plugs use a "monolithic" resistor, generally made of graphite and glass materials, to filter the electrical voltage as it passes through the center electrode. This "filter" reduces RFI to an acceptable level. Although this type of resistor develops from 1000 to 5000 ohms of resistance, there is no significant loss of voltage to affect ignitability at the electrodes in modern automotive ignition systems.

However, outboard marine engines utilizing a CDI system have a much lower voltage output, which would be compromised by a standard resistor plug. Therefore, an inductive resistor is used. In this method, a coiled nickel wire is inserted into the center stem, and held in place by a spring.

This coil basically acts as an electromagnet, inducing a magnetic field around the center stem, creating a natural "field" resistor, and reduces RFI to acceptable levels. This method creates only 40 ohms of physical resistance, compared to the 1000 to 5000 ohms of resistance in "monolithic" resistor plugs.

While NGK Inductive Resistor Spark Plugs cost more than standard resistor plugs, they provide major benefits in late-model marine outboard applications.



Regards !

 

[silverado82481]

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

well I have put on a new stator, new revlimiter and new cdi box ( rectifier ) epic fail....... no change. the trigger is still in the mail i will put that sucker on when it gets here. bummed !!!!!

 

[silverado82481]

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

Hahahaha

Yes, you come to a point you think the boat is poltergeisted.


Well after working on this engine for some month now i start to learn it. And i have never seen someting/engine that act like this. The conclusion is that if something that is bad ore so-so, it can kill another thing easy on this engine.

It?s too bad, becaurse it?s a okay boat and engine (shlurping gas like a elephant) when it works as it shall. I?m thinking on mounting of the 120XR engine and put on something else on top. A V-six ore some 4 that rev up to 7-8000. Ore a TD engine had been best for the wallet , but probably to low rpm.


We can start a therapy-helping group soon here. So we dont end up at KO-KO nest, all Merc. 90-120 owners


Regards from Sweden ( with the boat running for the moment )

is there a nother block that will mount up to these these I only have the 95xr but would love to get this thing to scream across the water !!!!!

 

[Anders67]

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

well I have put on a new stator, new revlimiter and new cdi box ( rectifier ) epic fail....... no change. the trigger is still in the mail i will put that sucker on when it gets here. bummed !!!!!

Not shure if 120XR will fit straigt on mecanical. But it is the same pump with different gearing ( lower on 95).

If the problem is still on the same cylinder. And no spark , it?s sound like trigger ore wiring. If you not have found anything else strange.

If it still not will fire on that cylinder for you. Drive a little with half gas ore so and kill the engine. Pull the Spark plug out and look on it. Is it wet of gasoline / whater,
ore complete dry ?.


Tell us how it goes with the new trigger.

 

[lexer440]

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

Revs up with plenty of power when i put the trottle down but like i said it wont plane out or gain any speed over 5 or 10 mph.

If this is correct then its thrust we have lost, not familiar with the boat but wondering if there is a key or pin in the shaft that mates with impellor? if so is it missing or sheared?

 

[boatparty]

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

Solution: I own a sportjet 120. Had same problem. 3 things make the boat fast.
1-clean propeller with no dings/work edges on blades make a MAJOR difference. Trust it. Either repair blade at a shop or get a new one...$150-400. cast iron or stainless works.
2-Wear ring tollerance between impeller and "ring" the blade sits in. I found that it needs a micro tollerance of IDEAL 0.030"!!! dissassemble lower unit nossle, blade stator, then wear ring (4 bolts). This will expose the impeller. Lots of oil will pour out so be carefull. The oil is for end of the shaft lube, remember to refill thru the hole on the stator ring. Measure by getting a spark plug feeler guage that you can slide in the gap to figure where your at now. JB weld worked for me. It is a 2 part liquid that hardens to steel. Simply expose wear ring and clean real good with sandpaper scuffing to roughen surface. mix JB weld. USE a 2inch putty blade (cut off handle so it easily fits in ring)or use a popsickle stick. Tape off areas you dont want JB weld on cuz it can get sloppy quick. Spread jb weld like butter evenly. Let dry. Machine shop cut back to right tollerance at a shop for $50-100 or sand down by hand (less accurate). I sanded mine and it worked fine. Improved plane by alot.
3-Ride plate HAS TO HAVE 100% seal between metal and fiberglass!!!! The exhaust runs in that chamber and it the seal breaks its game over. If a screw comes loose or falls out it is game over. MAKE sure it is sealed perfectly. I had a busted up old seal and I caulked the hell out of it and it worked until the exhaust heat did it in. I bought a new one from Merc for $74 and replaced all of the bolts on the bottom(8qty). Remember to use marine grade ATB Sillicone around inner metal to metal seal. ($6-8) hardware store or auto store.

I had to do all three to get back on plane. Lucky you have only one issue.....for now! lol.

 

[silverado82481]

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

Not shure if 120XR will fit straigt on mecanical. But it is the same pump with different gearing ( lower on 95).

If the problem is still on the same cylinder. And no spark , it?s sound like trigger ore wiring. If you not have found anything else strange.

If it still not will fire on that cylinder for you. Drive a little with half gas ore so and kill the engine. Pull the Spark plug out and look on it. Is it wet of gasoline / whater,
ore complete dry ?.


Tell us how it goes with the new trigger.

the new trigger didn not make a difference at all still reving to 5500 to 6000 rpm then after a second or two its cutting back to 4500 ( always 4500 never changes ) heres whats weird every time i try to plane off it only takes a second or two then cuts back when i replaced the regulator and the rev limiter with out the new trigger, It stayed at 6000rpm for like 5 seconds then cut back to 4500rpm then ever time after, that it only took a second or two. so as of now im completly stumped. bummed and jsut ready to sell the dam thing. but i know its got to be something dum and i would love to see what this thing can do when its runnig right. this is so frustrating dose any one have a complete wireing diagram for the 95xr sport jet ill go tru everything and make sure everything is right

 

[Anders67]

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

http://www.cdielectronics.com/InstallSheet/IS-114-7509.pdf




http://motorka.org/doc/mercury/service_manual/jet/SJ90_120_95xr_125xr_831996r1/sec2b.pdf



How does it die?. Just sharp cut of ore hesitate before dies?.



Is it the same cylinder that dies?. Kill it with kill switch when it happends and see if plug wet of gasoline ore complete dry. Black / brown color on spark plug?.

Changed sparkplug ?. Also check high power leads from CDM to spark plug, so full contact. If you can , ohm them and the CDM.

Things i can think of:

I had a CDM that was like that worked ok on low to middle rpm, then died on high rpm, you can not borrow some and test.



If it should be the rew limiter you can just unplug it and test, but new should work, if not wrong rpm cut out.

Volt test the kill switch lead and see what volt you have in on and of position, of key switch. should be under 2 volt max.

Also the reticif. you can just unplug and test.


Elctric harness ok???, double check negativ ground of CDM modules. Conection plugs fully contact and tight fit.



Also check the carb on that cylinder that dies. You have cleaned out and checked the yellow evap-hose that goes between the carbs and air intake?. Also the connection for that one in to the carbs, so they are cleared and free.

Fuelpressure if it only happen?s on hig rpm. Filters in pump lid ore lines, filter, handpump, pick-up. So it?s free for full gas flow.

I had one carb that had a little piece of debris laying before the needle jet ( on the side the fuel hose are connected to the carb). Make it go on low rpm but up on full rpm it closed of the fuel supply. Didn?t find that one before i unscrewed the hose connection in to the carb.

 

[silverado82481]

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

no hesitation or spiting and sputtering .... you would swear im backing off the throttle by hand im look ing to buy a manual and have all the information i need and start fresh i set this thing back on the back burner for now and trying to get my jetski up and going all the parts are there for that jsut havent nhad time to fix it. the season is comming to an end i need to get out on the water on something before it gets cold !!!! but im sure ill be turning wrenches on this thing when i get time to

 

[Anders67]

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

So did mine do when the carb cut of of the debris in fuel inlet. But it can also be a electric problem so you need to check things up to be shure.

When it happends kill the engine with kill switch and read the plugs. Especially the one cylinder that you says die.

 

[heisle]

Ive been working on this boat for a few months and have her runnng great. My problem is i cant get the boat to plane out or gain any kind of speed. I thought it was the ride plate seal so i replaced that this morning and took the boat out for a test just to find out it still doing the same thing. Revs up with plenty of power when i put the trottle down but like i said it wont plane out or gain any speed over 5 or 10 mph. Is there something else that could be the problem, i would hate to go out and buy a new impeller and wear ring and still have the same issue. Any thing any one can think of that might be the issue?

Hi, I was hoping that you figured out this problem. I know it's been along time since you posted this but I'm hoping that you can help me? I replaced, stator trigger, flywheel, whole ignition system including starter. I changed the ride plate seal, it's not perfectly lined up, but it should be good enough to go.

I have little propulsion, but the engine seems to be running strong.