Suzuki DT65 -88 - Difficult engine problem

[Sealfie]

Hello! As a last resort for im asking you all here for help.

I have a Suzuki DT65 -88 that wont rev/run properly. However, it starts very easy. To get it to rev at all (in gear) I must put some choke on. Therefore I assume its a carburator problem (lack of fuel). There is an airscrew or whatever its called and its now screwed in on max (moore fuel) (runs worse if u screw it out). I got no tachometer so I cant really tell you how much I can rev but I would say max 4000 rpm. The top speed is 21 knots with my Jofa 485, it should easily do 30-35 knots.

-The cylindertemp sensor (for warning) is unplugged
-The throttle sensor is unplugged (if I had this plugged in the engine would stop after exactly 15 seconds every time)
-The VRO is disconnected including the sensors

Things that has been done so far:
-Cleaned carburators very strictly. Everything looks very good and Ive even done this twice. One time even with an ultrasound-cleaner.
-The reeds are new
-Fuel pump is new including hoses
-Tried with another fuel tank and hoses to it, made no difference
-Cylinder compression is good

I dont have the indicators or anything for the warning system on the engine, however ive bridged the cables that was suppose to go to the reset button. How can I say if the engine is limiting the rev to 3000 rpm? Does it sound like running on the revlimiter on cars?

The engine temperatur have also been measured manually and it was all good.

Im running out of ideas....Thanks in advance!!

Its also consuming ALOT of fuel. about 1,7-1,8 liters per nautical mile.
Another really odd thing was that it went even worse at first (top speed 6 knots). But then I fueled up with 98-octane fuel (less ethanol) and some sort of fuel system cleaner. Then it went ALOT better after a while, but not good of course. I find this so strange when I know for certain that the carburators look fine.

 

[mphelle8vld]

You may have introduced other problems but that motor won't run properly without the throttle sensor hooked up and properly adjusted. It's only running for 15sec because the cdi advances the timing for that long on a cold start.

 

[lakensea]

1. Reconnect temperature sensor - replace if out of specs.
2. Reconnect throttle sensor - replace if out of specs.
3. Reinstall oil injection system as original
4. Purchase and install tachometer
5. Purchase & install monitor gauge
6. Run boat and enjoy.

 

[Sealfie]

You may have introduced other problems but that motor won't run properly without the throttle sensor hooked up and properly adjusted. It's only running for 15sec because the cdi advances the timing for that long on a cold start.

Ive cut the cable telling the CDI that its running on idle. The other cable (and earth of course) is plugged in telling the CDI thats its not on idle, also tried to unplug that one to with no difference at all.

 

[Sealfie]

1. Reconnect temperature sensor - replace if out of specs.
2. Reconnect throttle sensor - replace if out of specs.
3. Reinstall oil injection system as original
4. Purchase and install tachometer
5. Purchase & install monitor gauge
6. Run boat and enjoy.

This all seems logic of course. But the temperatur sensor is just for warning and wont do anything if its not too hot. According to the wiring diagram its like a switch. So if its unplugged the only thing that will happen is that the CDI think it runs within temp spec.

I will try to investigate the throttle sensor.

I unplugged the oil injection myself. I prefer to mix myself. Shouldnt make any difference to my problem or?

Purchase a original tachometer and monitor is very expensive. But its of course worth it if i get the engine to run properly .

I noticed one interesting thing and it was that the visible gear counter coil have 2 cables. One of them is cut. Will investigate..