Joined: 14 Jul 2018
|Posted: Fri Aug 03, 2018 6:52 am Post subject: 200 opti won't restart without unplugging both temp sensors
|So I'm hoping there's some advanced Merc opti sportjet folks out there. I have a 2003 200HP M2 sportjet opti with 240 hours on it.
My head's bleeding from scratching it!!!
Symptom: Engine starts fine cold but will not restart if you shut it off. By unplugging both the starboard and port temp sensors the engine starts up everytime as the ECU temps defaults to 32F and fuel is increased. On the water the engine seems to run OK with temp sensors plugged in. It looks like it's pulling full RPM (5650) on the dash gauge. Pulling 5500 for sure.
- Sent Fuel injectors for leak testing and cleaning. New filter screens installed as there was some 'junk' in there and all pass now. Initially thought there was a leaking injector causing the restart issue. Thought it was flooding as I could get it going sometimes with giving it some throttle or full throttle. Recently discovering it will start with both temp sensor unplugged so it's a lean condition not rich.
- Cleaned tips of air injectors by soaking in intake cleaner and washing with tooth brush.
- Changed fuel water separator filter.
- Inspected VST and no crud found or anything else.
- Fuel and air pressure are in spec.
- Lift pump works and pressure in spec.
- With only high pressure pump plugged in the pump will still build full pressure, just takes longer. So pump is strong.
- Air and fuel injector pulse/click tests pass.
- Spark is good.
- All 4 temps sensor ECU values are within a degree of actual temp when checked with infrared gun.
- Cyl cut out tests all good.
Note** Engine will not restart with just one of the head temp sensors unplugged. You need to unplug both and then it starts strong.
Question 1: Does anyone know if the ECU learns and stores fuel table adjustments in it's ROM? If so then it would need to be reset after injector service affecting fuelling which I would be looking for some guidance on this as I only have Merc G3 software.
Question 2: What else other than injectors and in-range High temp sensor values cause a lean condition on restart?
I'm going to check today to see if there's much difference in the temp sensor values on the initial start vs the restart attempt. I don't think there was a difference as I haven't been running it long with no water connected.
Thanks in advance for any help with this! I don't feel confident about running this thing with the two temp sensors unplugged.