Sport Jet - Force MOSFET Rectifier Regulator

[Cobra Jet Steering LLC]

ok we are on a different type of pump all together than what I was referring to. Glad you are getting this project going in the right direction.

 

[RedBarron55]

When I took the fuel pump apart I found the small plastic discs and they gad bulged the rubber discs and also the thick gaskets were in the wrong place, next to the outside plates instead of next to the inner part.
I have no idea if this makes any difference at all, but...
With much searching I found that the large diameter plastic discs (the same size as the rubber discs) go in WITHOUT the rubber discs!
The plastic expanding pins need to be installed so that they do not bulge the discs so the inner pins are not set all the way in, but just enough to seal the pin.
So the fuel pump comes off and apart again.
The third time is the charm?
I understand that the rubber discs have been replaced for compatibility with 10% blend ethanol gasoline.
I have been looking for a Mercury instruction for the rebuild, but have not found one yet.
I have seen partial listings on Google, but the links don't go through.

 

[RedBarron55]

Fuel pump re-reworked removing rubber check discs, leaving the plastic ones and test ran including the electric priming pump.
That is the good news, but some bad news that really might be good.
Checking the firing of all three cylinders with a timing light the # 1 and #2 cylinders have spark, but the #3 only intermittently.
The coil checks OK and the trigger coil resistance matches the other two.
I will check further tomorrow, but I have anticipated a problem with the CDI system and have bought the parts (used) to build a CDM system.
I felt like there were too many wires and pieces in the CDI system to fail and harder to isolate.
I have the CDM modules and I am now waiting for the used harness for a three cylinder I bought off ebay.
For a last minute update I decided to check the plugs like would an aircraft plug.
Aircraft plugs are resistor types like the plugs that were installed when I bought the boat.
I pulled the bottom plug and checked the resistance from the terminal to the tip and found it very high and changing. The other plugs read about 4K ohms.
I had bought a set of surface gap plugs to install and they are not resistor plugs and of course read 0 Ohms.
Since there was no discharge there was no magnetic field for the timing light to pick up (maybe).
So if I am lucky when I test run the motor it will fire all 3 cylinders.
This could be my problem since it would pull 4000 rpms and the specs on the boat say that this is 66% power.
Two of three cylinders = 66% so??

 

[RedBarron55]

Oh the disappointment!
I put the boat in the water to test this weekend and still can't pull over 4200 rpm, but the regulator works well.
I did find that even though I thought I had the built in tank dry inside, but ended up with water in the separator and perhaps in the carbs.
I have pulled the carbs again to inspect and re-clean and while I was there I pulled the reed valves and took a look at the rods and crankcase. The rods looked straight and the chamber was clean and the reed valves look to be like new.
I have received the plugs and harness for the CDMs I bought and I think I will get the engine back together and pilish the fuel in the tank by circulating the fuel through the filter / separator and back into the tank.
I found a lot of water in the filter when I checked it and emptied it into a glass bowl. I think that some of this may have gotten into the carbs.

 

[RedBarron55]

OK an update.
I polished the fuel through the added on filter separator, emptying it several times until there was no water found.
I circulated the fuel with the added Electrical priming pump through the filter and back into the tank agitating the tank (read boat) and using a small tube to try to get everything out of the corners etc.
While doing that I also bought three CDM modules of Ebay for about $45 with shipping and a $20 wiring harness off a 50 hp "mercury" that also used the CDMs.
This cleaned up the wiring when the CDI modules and wires were removed.
While Working and checking I found that trigger has some bad readings so I bought a new CDI unit andinstalled it.
By the way the warning that the Mercury had many different firing orders and found that the old color codes were different and took a little figuring out to get the engine running.
I hope that all of this takes care of the problem with not pulling 0ver 4000 rpm underway. With the trigger coil flakey it may have been breaking down under load.
I like the newer CDM modules without the switch box and adapter for the red coil.
This should mean that the possible electrical problems would be much less with the new rectifier / regulator and CDMs.
Also I can buy another CDM and have a spare that can go in the tool box, just in case.

 

[RedBarron55]

Finally!
I got the engine pulling 5000 rpm and drove it around the sound for a while this morning, before the rain sets in.
I checked the timing and had a problem with it being different from the cranking speed by quite a bit.
One problem was the advance being too high as I went from idle to WOT.
The timing would go pretty high over 30* and I stopped short of WOT.
I had to readjust the setting screw to get the timing retarded a little bit of a bother in the water at the dock.
What happens is the timing will exceed 30* and then it will back up to 30* at WOT.
I assume that the lower throttle setting and advanced timing is for better fuel economy at cruise.
Does anyone know it this is correct?
The timing is correct when the manifold pressure and RPM is high and perhaps this will not cause detonation and burn holes in the piston tops.
So closer and closer we come...
The GPS showed a little over 30 mph at 5000 rpm and that sounds a little low according to old test when the boat was new.
Of course the speed measurement in 1995 might be a little off with 36 mph at 5000 and 37.4 at 5100.
We didn't spend a lot of time running speed tests and it was b bit windy and choppy and I don't know i would have wanted to go a lot faster, either.
It does handle well with the Cobra Jet Steering mod - Thanks Jeff!
Of course I don't know how it would be without, but it is great with them.
With two in the back the boat wanted to porpoise a little at speed and the plate might need to be adjusted a little or the weight shifted.
One moved to the front works ok.