Force 120hp won't start

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
You have to turn it upside down and let it fall to where the main jet is located. Not touching but closest to it. And the other way parallel to the body.
What is the problem with your motor now?
Look a few posts back....bad idle mainly. Hard to start.... And when choking gas is comming out of the back from carbs
 

gica

Chief Petty Officer
Joined
Feb 24, 2016
Messages
495
Look a few posts back....bad idle mainly. Hard to start.... And when choking gas is comming out of the back from carbs
So gas coming out when choking could be one or more reeds defective. There are 4. Mine are stainless steel. The engine is not leveled when cranking. The needle valve not stopping the fuel when bowl is full. If you have the carbs out press the float in and blow through the fuel line make sure it completely blocks air. If you have a water or an air leak in the engine, if any of the seals are bad, ignition sparking the wrong way could trigger weird or no idle.
On one of my engines 120hp Force 1990
I could not keep it idling in gear on the lake only. So I changed the stator and trigger first. That improved the spark and start. I found exhaust water leaking in the 3 and 4 piston chamber. Took off the exhaust cover, had to resurface it with a fine stone by hand and check the warping. I also bought a new separation plate for 85 bucks and used sealant to put it all back with new gaskets. No more leak but I still have issues at idle in gear. The gas lines are all new, pump new, carbs rebuilt and adjusted. The quality of my gas is in question since it is 1.5 year old. I did add the stabilizer a few months back. There were 60 gallons at first now it's down to 20 or so. I did notice that on the second engine the filter is no longer holding gas in it after running on the lake. It does hold it if not running. That is a first. It must be because of the gas moving around in the tank and causing air to get in but it does work fine while running gas goes through. I rebuilt the motor completely pistons and everything last year. I also completely rebuilt the lower drive that was full of water. I am mechanically inclined but still get help here. More voices are always better. Make sure you check the values on the ignition with a DVA adapter and a meter per CDI website instructions.
And get one of those spark testers that you can adjust to see if you're getting spark at different distances between 3/8 and 1/2. Also if your flywheel has cracked magnets it might cause issues I changed mine already. My idle issue in gear is still somewhat of a mystery. When I conpletely consume all the old gas I will see if that is it. Otherwise it has to be not enough strong spark doing it. There is nothing else It runs amazing when I take off and sometimes it stays in idle in gear but if warmed up it is not perfect. Cold it's great. These are simple engines but old tech no sensors you have to measure everything. The newer ones are easier to diagnose sort of, because of the computerized systems that throw codes.
 
Last edited:

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
Ok. Engine is completely rebuild. Pistons gadgets, bearings. Fuelpump rebuild. New flywheel new. Tested all with dva tester. New starter. Etc... Carbs rebuild. Timing 28 WOT. Reeds where looking good, but very sticky on the holder. Had to push quite hard to open them. Waiting for boyesen reeds, then hope it runs GOOD. VERY hard to get parts here in the netherlands. And very expensive. Ore else..... I think I have thrown away a lot of money.
 

gica

Chief Petty Officer
Joined
Feb 24, 2016
Messages
495
I guess the reeds being stickymight be an issue. Are they plastic or stainless?
 

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
So new reeds arrived from boyesen. Looks good. Sadly weather sucks to put them on the motor
 

Attachments

  • IMG20240605182856.jpg
    IMG20240605182856.jpg
    4.9 MB · Views: 2
  • IMG20240605182905.jpg
    IMG20240605182905.jpg
    5 MB · Views: 2
  • IMG20240605184654.jpg
    IMG20240605184654.jpg
    5.1 MB · Views: 2

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
Stil no luck. Runs a little bit better. Bad idle still. Taking the engine apart. Looking for leaks ore something.
 

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
Took it almost apart. I notist piston slap.... Good this be the problem of bad idle. Compression is 120 on Al 4 cilinders
 
Top