OldButSlow
Cadet
- Joined
- Jan 23, 2021
- Messages
- 7
89 50hp 2 stroke - Starts right up, runs well at idle for 22 seconds and shuts off abruptly. If I raise the idle speed with either idle adjustment screw or at the throttle, still dies at about 22 seconds. Always 21-23 seconds, no matter what rpm. Always restarts immediately with just a bump of the starter. Then dies at 22 seconds again. Oil injection has been removed. Can't verify that if it has ever run correctly since it was disabled/removed. But the 3 wire connector from the oil injection control unit is disconnected, so no possibility of the oil level sensor reported back a grounded condition via the pink or yellow wires to the wiring harness. Compression good in all 3 cylinders (7 psi difference top to bottom), cleaned, reinstalled and verified sync on carbs, reeds closing up well, tried various settings of idle air mixture screws. No change except sputters out within 10-15 seconds when idle air screws are run in past 1 turn out. All are set back to 1 3/4 turns out. Also ran with second, known good pre-mix fuel from different tank, with different fuel line & primer bulb. Bulb stays tight. No change. Good blue spark on all three plugs and same with spark tester in place of plugs. Resistance tests of all ignition coils within spec. Resistance tests of charge coil, lighting coil and pulse coils, all within spec. Ran with temp sensor disconnected (pink wires), no change. Checked for continuity to ground; found none. Ran with stop circuit disconnected, no change. Ran with remote start switch to the starter solenoid, with entire wiring harness to ignition switch disconnected; no change. Has new impeller with strong flow. Removed thermostat and verified good flow of water through the housing. Resistance checks of CDI unit all check out within spec except that I show some continuity between yellow/red (overheat circuit) wire and black/white output to coil wires. Factory manual shows no continuity expected. But, the wiring diagram shows yellow/red wire (coming out of the CDI unit) with nothing connecting to it. Which is how I found it as well; nothing connected to it. Does anyone know if there is circuitry in the CDI unit (6H5-85540-02-00) which has the ability to shut off spark after a predetermined time cycle if it "thinks" the engine is overheating? Seeing continuity on that yellow/red "overheat" wire has me suspecting some damage internally in the CDI, even though the "overheat" wire isn't used on this particular engine (or any other covered by my factory service manual. This one is a head scratcher, but I hate to spend $500-600 on a new CDI unit and then have to eat it if it doesn't correct the issue.