1990 Force 120 idling problem

[Tylerc420]

-Cranks...
-Starts...
-Idles... for 1-10secs dies instantly randomly, idle at around 1100rpms cowl off, muffs on
give it some throttle, higher rpms, idles fine, 1500rpms
will do it for about 10mins-15mins and then wont want to crank over, batteries will be dead, ran
for the longest it has, about a minute at around 1500rpms, then slow crank/wouldnt start after
about 5 more times of it starting/dying within 10secs

last year_______
last year it would have a real hard time starting, when it started it would idle but roughly, id
have to start it and throw it in forward/reverse almost instantly to keep it running, if i tried
to put it in gear it would die

-Its getting gas 100% ive checked every line
-Cleaned carbs, checked carbs, theyre fine, nothing clogged or anything,they where clean as new when
took them apart
-All plugs have spark
-Took flywheel off, sandpaper/cleaned rust off stator/flywheel same thing happens afterwards..

what could cause this?

 

[Tylerc420]

update: went to go try and start it and see what happens, cranks slowly doesn't start (never charged batteries from last night) expected that but... the negative connection on one of the batteries started smoking so I stopped and took them off... didn't expect that..

 

[jerryjerry05]

First thing: do a compression test.
Remove all the plugs to do the test.

The hot connections, could be loose or corroded or the starters dirty/dragging.

Do the comp test, then check the starter and cables.
Post the results.

 

[Tylerc420]

First thing: do a compression test.
Remove all the plugs to do the test.

The hot connections, could be loose or corroded or the starters dirty/dragging.

Do the comp test, then check the starter and cables.
Post the results.

Compression is 130 on all 4, wires on starter are good and everything. It starts fine. Just doesn’t fire and keep running. It’s now backfiring and the idle mixtures are at 1 1/2 turns out

 

[Tylerc420]

And I mean cranks over fine, doesn’t start sorry

 

[Jiggz]

If you haven't done so:
1. Disconnect the negative cable from the engine block, sandpaper it clean and shiny and same with the mating surface on the block. Re-install and tighten
2. Install a clear fuel filter between the fuel pump outlet and the carb inlet. Prime it and make sure it is at least half~3/4 full.
3. Post a pic of the cam and roller position focusing on the markings.
4. Even better post a video of the motor running or starting or cranking.

 

[jerryjerry05]

Backfiring: could be sucking air somewhere?
Starting fluid, spray around the intake side.
That includes the fuel pump and port covers under the pump.