Sport Jet - Force MOSFET Rectifier Regulator

[RedBarron55]

I finally got my 90 HP Sport Jet Hobie Jet Fisherman running out on the water for a little while.
I noticed that the voltage went over 18 volts and that worries me.
On reading the CDI website that this engine should not use maintenance free batteries I assume because the load when charged lets the voltage increase.
Since I already have the maintenance free battery and I bought a motorcycle MOSFET rectifier/regulator in case I needed and I think it will replace the Force/Mercury one.
I bought this one (rated for 50 amps peak and 30 amps continuous single phase) for a Suzuki Boulevard GSXR Bandit 2003-2011 from Ebay for $15.99.

https://www.ebay.com/itm/Mosfet-Voltage-Regulator-Rectifier-FITS-Suzuki-Boulevard-GSXR-Bandit-2003-2011/322519368482?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

This unit is for a three phase alternator coil, but it will work on two if you just don't connect the third yellow wire.
I made an adapter harness that would plug into the existing connectors on the engine and paralleled a second wire with one yellow to feed the tach since it does not have a gray wire for that connection.
I installed this on an aluminum plate mounted on the transom starboard of the engine extending the wires to reach.
Running it for a while on the hose it gets warm, but the way all of these work is that they dissipate the excess power instead of letting the voltage rise over 14.7 volts.
Where the stock unit let the voltage rise over 18+ volts this regulator holds it to 14.8 with the battery completely charged.
This might save the rest of the system from high voltage failures.
By the way I have the red stator installed on the engine meaning that this should be good for higher current than the original system.
As an aside I am also working on converting the ignition to CDM with the modules and wiring harness.
My assumption is that with the proper plugs I can use the wiring diagram from the manual for the CDM to hook it up.
I have the red stator and the single magnet, three output trigger unit that need to go together.
If there are an observations on the pluses and minuses on wither system I would be glad to hear them as the cold weather has kept me off the water and brought the outside work to a halt.

 

[Cobra Jet Steering LLC]

I posted a while back on that subject , a jet ski regulator works fine this will also protect your brain from being destroyed due to a faulty rectifier
https://jetboaters.net/threads/sportjet-120-ignition.12682/#post-220655

 

[RedBarron55]

Thanks for the input.
You are exactly right on the voltage etc.
I bought my rectifier for a motorcycle because I couldn't find a good reference for a jetski regulator.
I am also in the process of updating to a CDM ignition, thinking it might be more reliable and maybe easier to troubleshoot.
We will see about that.
So far the new regulator is working oK, but I don't have much runtime on it except on the hose.
At least I can run it on the hose and on the water without filling the cylinders with water.

 

[Cobra Jet Steering LLC]

With a voltage regulator installed you should be fine with the stock stator and brain . I would now look very seriously at the spark plug wire cores as those will deteriorate inside the wire and cause you to have serious run issues , as the engine warms up the r p m's will drop severely.
Another thing you need to look at is the fuel lines , those black rubber original automotive style lines eventually have particles that break off inside , the little pieces block off the fuel trying to enter the carb needle and seat I had to replace all those to keep the fuel flowing to each carb especially the top one . and be sure the fuel tank is totally clean if you have any trash in it the fuel pickup in the tank will collect that trash and slowly choke off the fuel to the engine.
Then when you shut off the engine the trash falls away from the fuel pickup and the entire situation starts over again. Also never use old fuel that was left in the tank, never add fresh fuel and expect it to fix the problem, flush out the fuel tank and start with fresh fuel .
I personally get rid of the pulse style fuel pump and install a small electric fuel pump with a 2.5 max pound pressure this one thing makes a world of difference at all speeds due to a constant steady fuel supply . it also eliminates the issues with tapping into the crank case pressures of one cylinder to operate the original pump and you just turn on the key for a few seconds to prime the system from the drivers seat.

 

[Cobra Jet Steering LLC]

New Regulator Rectifier for Yamaha 1000 FX1000 F…

$19.00

Free shipping

 

[RedBarron55]

Thanks for the reply, Jeff.
I have a fuel pump kit and a small electric pump as a back up and to prime.
I have bought the CDM modules for $50.00 and the harness for $25 and I am making the changes as much to simplify the system as much as anything. I can carry a spare module and regulator and a set of plugs and have a good chance of getting back home.
Once I get the thing running correctly (and not leaking into the cylinders) I should be set and than perhaps I can sell the CDI parts to cover the cost of the upgrade.
The last time I was out the engine would not rev over about 4200 rpm and quit on the built-in tank with the water separator and filter. The portable tank ran, but still bogged down at full throttle (still only 4200).
I think that when I took the ignition plate off the brown wire to the connection from the trigger to the rev limiter and Brain might have been loose as it came off very easily.
I could have a problem with the rev limiter, still with ignition to #3 or low fuel pressure.
First things first.
I am going to rebuild the fuel pump and install the electric primer/"boost" pump and disconnect the rev limiter and test again with some new plugs.
If I get it running OK to 5000 + rpm and prove the fuel / carbs (Cleaned and checked) then I am planning to proceed tot the CDM upgrade.
I think that the CDM would be worth while to clean up the wiring and make it more logical, perhaps.
That would also give me room to install the regulator on the engine plate instead of the transom.
The low RPM could be one or more things:
1. Low Fuel delivery and low level in the bowls
2. Crap in a carb.
3. Bad Rev Limiter
4. Bad connection (Brown lead from trigger)
5. Bad coil
6. Bad plug wire.
7. Restricted flow through the Attwood quick connect anti-spray couplings used on both tanks!
8. Bad Karma

 

[RedBarron55]

Does the Yamaha Regulator come with the plug and wires?
I might change the Motorcycle one out if that one fits in the original spot.

 

[Cobra Jet Steering LLC]

I have no idea if they provide wires but that should be pretty easy to deal with plus there are numerous other inexpensive types available on line that have the wires , I just hit that one to show that they were not expensive I was not necessarily saying to get that particular one. I have seen the smaller ones with the wires for the same price like a sea doo or any 2 stroke regulator I use them in place of the electrolytic capacitor that the older engines use since the regulators save your battery from overcharging etc. and in your case if the old one goes bad as soon as you turn off your engine the brain fries no exceptions, it took years to find the real reason the brains would fail and each time the engine was running and once it shut off the brain failed and the engine lost ignition. They tried to blame the old stators and built new ones but it still happened .

 

[Scottintexas]

Jeff, is the regulator only a Mercury issue or did the old Yamaha and seadoos also have this issue?

 

[Cobra Jet Steering LLC]

It was the kiss of death for the FORCE outboard engines and he has a 90 hp Force power head the 120 and 90 hp power heads had serious issues with electronics there are a diminishing number of these still around both the outboard engines and the jet pump engines.
I posted a lot about the issues with those many times in the past sadly if you replaced the brain and the stator but you did not realize the rectifier was bad as soon as you started the engine after fixing it and you were all happy that it was running, when you turned off the engine it would destroy the brain box instantly.
Any way I made a relay to totally disconnect the positive battery terminal when the key was turned off just as a backup to prevent D C current from traveling back to the charging system windings that are next to the ignition windings and as the flywheel turns for a second with the ignition turned off and D C current traveled back to the stator due to a defective rectifier charging the stator creating a bastard field that would take out the brain instantly. That is the short version of it. But it is what it is.

 

[RedBarron55]

It may have to do with the magnetic field building up from the hi current of a shorted diode and then collapsing when the engine stops and the surge may be induced into the two coils of the ignition circuit.
I think that the coils share the same iron laminations and the ignition coils may act like the secondary windings of a transformer.
Either way I thought that a MOSFET rectifier /regulator might take care of both the regulation and death by rectifier issues.
Thanks to Jeff for bringing this to my attention.
I saw the note that only flooded cell batteries should be used on the CDI website due to the voltage going high and killing the modules due to over-voltage.
Since I already had the maintenance free battery I thought I would try Jeff's fix.
I assume that Mercury would rather use the excess energy in the charging system to boil water in the battery rather than create heat in the regulator and coils. Of course the same amount of current will be generated either way, but the batteries live linger with the better regulator

 

[RedBarron55]

Jeff, I think that if IF the electronic problems are sorted out the Force may make a good power plant for the Sport Jet.
It needs to since there are few if any other choices available!
In my case if the engine hasn't been damaged with all of the water getting into it and various abuses from previous owners It might just work out for a good bay skiff that can get into shallow water.
By the way I ran the thing in fairly shallow water at the dock while testing and I think that the odd intake may help in not picking up sand and debris from a shallow bottom since the plate on the bottom directs water from in front of the pickup and probably acts like a Top charge inlet.

Hopefully the extra drag of it sticking down under the boat is partially offset by ramming water in.
Who knows?

 

[Cobra Jet Steering LLC]

Actually if you have an older 2 stroke engine with a rectifier like the one I am posting a picture of,, you would be wise to remove it and replace it with an electronic regulator module as the old rectifier will allow super high voltage even as high as 18 volts depending on the typr of motor and that voltage will really play hell with your battery and electronics.

there are just electrolytic diodes that chop the ac current in half and act as a 1 way door when they work but they do not regulate the voltage at all.

 

[Cobra Jet Steering LLC]

I believe you may have one that someone changed over from an outboard to a jet as there were a few differences in the intake manifold and a few other items but the block was the same
who knows about that intake it just may be good time will tell but I never have seen another one like it

 

[RedBarron55]

I believe you are correct.
The Previous owner bought the engine as either low time or rebuilt and I think since it has to have the sport jet crank (due to different splines for the outboard) I think that it is a B@STARD made up of the sport jet crank and an outboard block.
The correct year for the boat and the original engine had the oil injection. The original engine also had the figure 8 furl pump and this one a square Mercury (late model?) pump.
I will get this thing sorted out and I am learning a lot along the way.

 

[Cobra Jet Steering LLC]

If it were me and I wanted to have a reliable boat I would be looking hard for a good power head that belongs on the pump , have it rebuilt and enjoy it. But quite honestly I have serious reservations about the J B WELD in the block where the screws stripped I think it may hold for a while but not for more than a year at best or months at worst.

 

[Cobra Jet Steering LLC]

So your pump is the mercury Optimax type for the 6 cylinder block??? if so look for one of those ,, way better setup in my opinion

 

[RedBarron55]

The pump is standard for the 90 jet and it seems to be in very good and nearly new condition with no wear on the wear ring or impeller.
I have seen 6 cylinder mercury jets on throw away jet boats earlier in the year for as little as $300, but they would a lot of work too.
The match up for the engine and pump is good and the issues are pretty much sorted.
Since I found the source of the leak there has been no more water getting into the cylinders.
The source was the old water inlet in the front of the cooling jacket that the outboard used and the jet does not.
I sealed this off and the gaskets and the manifold have held pretty good.
I replaced the head gasket and had the head off a second time (reused the gasket with Hylomar Blue) and it seems to work OK too.
I did get the replacement head gasket the other day and may replace it later along with the exhaust manifold gasket.
I used a force gasket and it seems that there is a different gasket for the jet and I may spend the extra money for the exact correct one.
Being retired I have a hard time justifying a Optimax 200, but that would be a great fit, but too much power.
The 15' 10" Hobie Fisherman jet matches the weight of the 90 and will go close to 40 mph and is pretty good for a 23 year old boat.
Of course to get that I need all three cylinders agreeing to run...right

 

[RedBarron55]

Today I pulled the square fuel pump off the Force 90 on the sport Jet and checked it out and it was bad!
To test blow in the inlet and it should pass the air, Blow on the outlet side and it should NOT, but mine did.
I took it apart and is had no torn or worn diaphragms but he had a fuel flow problem athe check valves had the small plastic back up discs where the new kit had the large ones.
There was only one check valve rubber disc so since there was no real fault with the old ones I reinstalled the best one (?) and the new one.
The newly rebuilt pump holds in the right direction and passes in the right direction too.
I also installed the electric primer pump as well and I hope to get it wired in this afternoon.
With the defective pump that may have starved the engine for fuel at high power and limited the RPM to ~4000.
I hope that this fixes that problem!
I saw somewhere that one owner rebuilt his carbs and installed the new style floats and had a similar problem and he determined that the new floats blocked the flow into the main jet. The old floats had recesses in them near where the jet would be IF the fuel level in the carb was low. Maybe he had a fuel flow problem as well since as I understand it the fuel level should be just off the cutoff point for the needle valve?
Either way if the flow with the engine pump is low I should be able to prove it by turning on the primer pump.
By the way I was finally able to get the timing adjusted where the cam and throttle sync could be set up as in the manual and the engine started right up from dead cold!

 

[RedBarron55]

So your pump is the mercury Optimax type for the 6 cylinder block??? if so look for one of those ,, way better setup in my opinion

I am not sure what the Optimax type pump is for sure.
Mine is the square pump that is used on lots of later model Mercuries and not the figure 8 one shown in the Sport Jet manual.
It looks like this: