Working on a 1996 Johnson 175 (J175SLEDB) with optical ignition system. Took for test run yesterday, owner says was cutting out as if turning ignition off. Had to run it over 3 miles to get it to cut out. No problems with primer bulb collapsing, pumping primer during cutout makes no impact. Engine will sometimes pick right back up and run perfect, sometimes not.
If engine dies completely, will start and run great after 5 minutes or so. Checked block temp with IR temp gauge immediately after stalling, highest temp I could find anywhere on powerhead was about 140 degrees.
Usually cuts out when running anywhere between 3500-4500 rpm. Noticed that sometimes if I hit WOT as it's starting to cut out, it will pick up and run fine for a while before eventually dying. Also noticed that once it starts to cut out, if you hit trim switch it acts like ignition was switched off...let off trim and engine picks back up. Once engine sits for 5-10 minutes and starts back up, trim operation has no effect. Battery is fairly new, never fails to start engine, trim works perfectly whether engine is running or not.
I've never messed with optical systems before. Almost seems to be acting like a voltage drain is causing some type of misfire, like on an old CD iginition system from pre-73 models that needed a hot battery to run...but the battery's in good shape.
I suspect a bad power pack, but would rather not spend the money just to find out something else is wrong.
Just to sum up:
Runs great for 20 minutes @3500-4500 rpm, then starts to cut out (sometimes completely, other times dropping 2-3 cylinders.
If engine drops 2-3 cylinders, running power trim will kill engine.
If engine drops 2-3 cylinders, hitting WOT will make it hit on all 6 for a few more minutes, after which engine shuts down completely.
Engine block temps well within operating range at time of shutdown, pumping plenty of water out of tattletale.
If engine dies, will start and run perfectly after about 5 minutes.
Tachometer is reading correctly all the time (in the old days, if your charging system fails, no tach, not sure if that applies here)
Problem does not seem to be fuel system related.
Any feed back would be great!
If engine dies completely, will start and run great after 5 minutes or so. Checked block temp with IR temp gauge immediately after stalling, highest temp I could find anywhere on powerhead was about 140 degrees.
Usually cuts out when running anywhere between 3500-4500 rpm. Noticed that sometimes if I hit WOT as it's starting to cut out, it will pick up and run fine for a while before eventually dying. Also noticed that once it starts to cut out, if you hit trim switch it acts like ignition was switched off...let off trim and engine picks back up. Once engine sits for 5-10 minutes and starts back up, trim operation has no effect. Battery is fairly new, never fails to start engine, trim works perfectly whether engine is running or not.
I've never messed with optical systems before. Almost seems to be acting like a voltage drain is causing some type of misfire, like on an old CD iginition system from pre-73 models that needed a hot battery to run...but the battery's in good shape.
I suspect a bad power pack, but would rather not spend the money just to find out something else is wrong.
Just to sum up:
Runs great for 20 minutes @3500-4500 rpm, then starts to cut out (sometimes completely, other times dropping 2-3 cylinders.
If engine drops 2-3 cylinders, running power trim will kill engine.
If engine drops 2-3 cylinders, hitting WOT will make it hit on all 6 for a few more minutes, after which engine shuts down completely.
Engine block temps well within operating range at time of shutdown, pumping plenty of water out of tattletale.
If engine dies, will start and run perfectly after about 5 minutes.
Tachometer is reading correctly all the time (in the old days, if your charging system fails, no tach, not sure if that applies here)
Problem does not seem to be fuel system related.
Any feed back would be great!
