Hi everyone,
First, let me apologize for the length of this post, but the history and details seem necessary to eliminate some suggestions that have been tried and tested.
I've been busy over the last few weeks working on the beast, but I'm making some headway. It's a 1990 120hp looper J120TLESB that's I bought after sitting for a few years from a fresh top end rebuild. The "mechanic" came highly recommended at the time, now I'd like to smack the guy who said that. I'm finding that the "mechanic" was very sloppy and did a fair amount of butchering on that motor. I'll recap what I've done, but it started with a motor that ran very well above @2000rpm but has a rough idle and seemed to intermittantly drop a cylinder. I couldn't seem to identify the bad cylinder, and thought it might be misfiring on all the cylinders at some point. Sometimes it ran pretty good, but sometimes it would cough and stall. I went through the fuel system, and tested the electrical as best I could without a DVA adaptor. I found the timing seemed to jump a bit and the stator had weak resistance. That was pretty much where we left it last time.
To recap the work (some of this was done prior):
*Compression @ 150, all within a few pounds
*New fuel tank, lines, filter (part of the boat re-build), hoses to and from the pump and primer, no water in system.
*Pulled intake and checked reeds, all looked good and seated with a few showing a glimmer of light through them.
*Found the "mechanic" had used his oldest chisel to scrape off the gaskets and had gouged up the manifolds and backsides of throtle bodies pretty well, some even scratched from edge to edge. I cleaned them up and reinstalled with new gaskets and some sealant for the scratched surfaces. It also seemed that he re-used the old gaskets for the throttle bodies.
*Found possible pinhole leak in plug for VRO, changed it.
*Tested fuel pump and primer, both tested well.
*Carbs spotlessly clean and floats set to perfection
*Butterflies synched to perfection
*Recirc valves and hoses checked
*All other hoses and nipples checked
*Checked all the wires in the harness for wear, all looked good, also replaced most of the regular electrical connectors he had used with heat seal ones. Found some that were pretty corroded up.
*Cleaned up every ground surface ("mechanic" had painted block after the rebuild and didn't bother cleaning the paint off the ground points and behind the starter.)
*Checked thermostats and found port one to be stuck open, changed them both (re-used the diaphragms, they seemed good and weren't cheap-was this a mistake not change them??)
*Regapped plugs (which are Champion QL77JC4,nearly new and clean) to .035" read some threads that said set them to .040 and some said to leave them at .030, so I split the difference.
*Plug wires are new OMC
*Coils are new OMC with clean ground surfaces
*Replaced the stator (new from Outboardparts).
*Replaced the powerpack (unused CDI off ebay for $40. with a guaranty)
*Replaced the timing base (new OMC off ebay $80. still in original box with stocking lable)
*Replaced regulator/rectifier (new CDI from dealer, read threads saying it was a good practice to change with the stator).
*Cleaned up flywheel magnets, all tight, and found a good size sliver of metal stuck in one of the slots on the inner magnetic ring, I suppose this might have thrown off the pickup on the timing base.
*Visually checked the upper bearing cap and seal, the cap was original but the seal was fairly new and looked good. There is some ever-so-slight play in the upper crank bearing, so slight it's hard to tell from rotating movement but it's definitely there. Not sure if a new bearing would be any better, love some input on that. I didn't pull it to check the orings out because I couldn't get a new seal quickly, but he did use some additional sealant on the base when he put it together.
*Lynched and synched
*Set idle timing and WOT timing
There may be more, but that's all I can think of for now. Some of these things I had done before and re-checked. The newer things like the ignition components and intake I didn't do all at once. I started with installing the new stator, powerpack and thermostats at the same time. That resulted in some improvement, especially in the intermittant cylinder drop, which mostly seemed to disappear. It still didn't run smoothly though, and would occasionally still idle up and sputter and die, then run okay again. It also did something new now, when motoring at high speed once, it seemed that the SLOW feature kicked in and held me to 2800 rpms. The temp guage still read cold (when I did the boat over, I unknowingly purchased the temp guage/sender that isn't just for outboards so it barely reads off cold all the time. Cruising throught the site here, I found my mistake too late, but the heads are not overheating, even with the new thermostats I can leave my hand on them after running WOT. It actually seems like the flywheel gets hotter than the heads). After the SLOW kicked in, I felt the heads and they seemed cool enough so I motored on. The motor came right up to speed again and ran fine for some time as I headed in. It did do it again one more time, but oddly kicked me down to 2800 for a few seconds then revved back up. Now I was beginning to think maybe my $40. powerpack was a dud so I put the old one back in to try it. The dropped cylinder problem came back and in testing I was finally able to find that it had a bad wire to #3 cylinder that dropped spark as I moved the orange lead. I put the new powerpack back in and got smoother running again but it seemed to have intermittant weak spark on testing across 7/16", sometimes it would do it, sometimes only @ 1/4". That was when I decided to check all the wiring and grounds and found some issues there (the "mechanic" painted the block after the rebuild, but didn't find the time to clean the paint off the ground surfaces). In that time, I also saw the new OMC timing base on ebay for cheap money so I bid on that and in the down time pulled the intake off and did all that work. I also decided since everything else was new, I should bite the bullet and replace the reg/rect. as recommended. Soooooo, I pulled it down to the block (left the heads on....) and built it back all good and new. Ran it up and it was smooth as glass, like a new motor (I was wearing that sh*t-eatin' grin all night!!!). Took it out the next day with a buddy to set the WOT timing (smooth as glass and running @ 5300 rpm) and it ran perfectly.....for a while. The intermittant running poorly, sputtering, idle came back. I had the timing light and checked the idle again an found it jumping around. I grounded the quickstart lead and it evened out. It also did the SLOW thing again once, for a brief moment, like the feature was switching on and off quickly, and then didn't do it again. The temp gauge still read cool.
Now, with all that done, this is what I'm thinking and I'd love some input. As for the idle issue, it's all electrical. The fuel system is perfect and it runs so smoothly and quietly until it has the problem, which seems to turn on and off like a switch. I also notice when it does act up, the motor is louder with a throaty sound, and the idle is higher. I'm guessing the quickstart is not disengaging and/or kicking in when it's not supposed to. The SLOW issue is new and also intermittant. That would leave it to be a bad powerpack (quite possible, given the purchase) or the temp sensor. I pulled both sensors and tested them with heat. The starboard kicked in @ 165deg and the port kicked the quickstart @ 125deg but the tan lead didn't register until much higher than the 165 of the starboard. It didn't seem to trip at first but eventually did trip though, and my thought would be if anything, it wouldn't be an issue for the idle problem unless it kicked in much lower. I also checked the diode in the tan lead, working fine. I'm leaning towards the new powerpack as the trouble. I purchased finally a DVA adaptor from mastertech (great guys!) and made some tests last night. The adaptor didn't really have much for instructions, but my understanding is that you connect it and set the meter for DC volts. My fluke is digital and auto ranging. I tested using the figures from rapair.com and found the timing base to be well within specs but found some discrepencies with the stator and powerpack:
brwn to brwn/yel: 588 ohms disconnected, 90 volts connected, (should be
950-1100 ohms and 150v- the chart for motors without
quickstart shows 450-550 ohms and 150v)
orng to orng/black: 96 ohms and 17-20v connected or disconnected (chart
shows 93-100ohms and 150v)
orange leads to coils to ground: 175-178volts on all, also, strong blue spark
on all cylinders.
Given these readings, it appears as if the stator is not putting out enough juice, but the spark is very strong and consistant. I assume I'm using the DVA correctly, please let me know if I need to set it differently. I'm going to take her out today and rig it so I can switch off the temp sensor leads for the quickstart and SLOW to see if I can isolate the problem to the sensor or powerpack.
Thanks for any of you who stuck through this long post, and for any input you might have! I think this motor has the potential to be very strong and reliable but it came to me with multiple issues, mostly stemming from some sloppy work. I've eliminated nearly all with lots of help and insight from here, now I can see light at the end of the tunnel.
Evan
First, let me apologize for the length of this post, but the history and details seem necessary to eliminate some suggestions that have been tried and tested.
I've been busy over the last few weeks working on the beast, but I'm making some headway. It's a 1990 120hp looper J120TLESB that's I bought after sitting for a few years from a fresh top end rebuild. The "mechanic" came highly recommended at the time, now I'd like to smack the guy who said that. I'm finding that the "mechanic" was very sloppy and did a fair amount of butchering on that motor. I'll recap what I've done, but it started with a motor that ran very well above @2000rpm but has a rough idle and seemed to intermittantly drop a cylinder. I couldn't seem to identify the bad cylinder, and thought it might be misfiring on all the cylinders at some point. Sometimes it ran pretty good, but sometimes it would cough and stall. I went through the fuel system, and tested the electrical as best I could without a DVA adaptor. I found the timing seemed to jump a bit and the stator had weak resistance. That was pretty much where we left it last time.
To recap the work (some of this was done prior):
*Compression @ 150, all within a few pounds
*New fuel tank, lines, filter (part of the boat re-build), hoses to and from the pump and primer, no water in system.
*Pulled intake and checked reeds, all looked good and seated with a few showing a glimmer of light through them.
*Found the "mechanic" had used his oldest chisel to scrape off the gaskets and had gouged up the manifolds and backsides of throtle bodies pretty well, some even scratched from edge to edge. I cleaned them up and reinstalled with new gaskets and some sealant for the scratched surfaces. It also seemed that he re-used the old gaskets for the throttle bodies.
*Found possible pinhole leak in plug for VRO, changed it.
*Tested fuel pump and primer, both tested well.
*Carbs spotlessly clean and floats set to perfection
*Butterflies synched to perfection
*Recirc valves and hoses checked
*All other hoses and nipples checked
*Checked all the wires in the harness for wear, all looked good, also replaced most of the regular electrical connectors he had used with heat seal ones. Found some that were pretty corroded up.
*Cleaned up every ground surface ("mechanic" had painted block after the rebuild and didn't bother cleaning the paint off the ground points and behind the starter.)
*Checked thermostats and found port one to be stuck open, changed them both (re-used the diaphragms, they seemed good and weren't cheap-was this a mistake not change them??)
*Regapped plugs (which are Champion QL77JC4,nearly new and clean) to .035" read some threads that said set them to .040 and some said to leave them at .030, so I split the difference.
*Plug wires are new OMC
*Coils are new OMC with clean ground surfaces
*Replaced the stator (new from Outboardparts).
*Replaced the powerpack (unused CDI off ebay for $40. with a guaranty)
*Replaced the timing base (new OMC off ebay $80. still in original box with stocking lable)
*Replaced regulator/rectifier (new CDI from dealer, read threads saying it was a good practice to change with the stator).
*Cleaned up flywheel magnets, all tight, and found a good size sliver of metal stuck in one of the slots on the inner magnetic ring, I suppose this might have thrown off the pickup on the timing base.
*Visually checked the upper bearing cap and seal, the cap was original but the seal was fairly new and looked good. There is some ever-so-slight play in the upper crank bearing, so slight it's hard to tell from rotating movement but it's definitely there. Not sure if a new bearing would be any better, love some input on that. I didn't pull it to check the orings out because I couldn't get a new seal quickly, but he did use some additional sealant on the base when he put it together.
*Lynched and synched
*Set idle timing and WOT timing
There may be more, but that's all I can think of for now. Some of these things I had done before and re-checked. The newer things like the ignition components and intake I didn't do all at once. I started with installing the new stator, powerpack and thermostats at the same time. That resulted in some improvement, especially in the intermittant cylinder drop, which mostly seemed to disappear. It still didn't run smoothly though, and would occasionally still idle up and sputter and die, then run okay again. It also did something new now, when motoring at high speed once, it seemed that the SLOW feature kicked in and held me to 2800 rpms. The temp guage still read cold (when I did the boat over, I unknowingly purchased the temp guage/sender that isn't just for outboards so it barely reads off cold all the time. Cruising throught the site here, I found my mistake too late, but the heads are not overheating, even with the new thermostats I can leave my hand on them after running WOT. It actually seems like the flywheel gets hotter than the heads). After the SLOW kicked in, I felt the heads and they seemed cool enough so I motored on. The motor came right up to speed again and ran fine for some time as I headed in. It did do it again one more time, but oddly kicked me down to 2800 for a few seconds then revved back up. Now I was beginning to think maybe my $40. powerpack was a dud so I put the old one back in to try it. The dropped cylinder problem came back and in testing I was finally able to find that it had a bad wire to #3 cylinder that dropped spark as I moved the orange lead. I put the new powerpack back in and got smoother running again but it seemed to have intermittant weak spark on testing across 7/16", sometimes it would do it, sometimes only @ 1/4". That was when I decided to check all the wiring and grounds and found some issues there (the "mechanic" painted the block after the rebuild, but didn't find the time to clean the paint off the ground surfaces). In that time, I also saw the new OMC timing base on ebay for cheap money so I bid on that and in the down time pulled the intake off and did all that work. I also decided since everything else was new, I should bite the bullet and replace the reg/rect. as recommended. Soooooo, I pulled it down to the block (left the heads on....) and built it back all good and new. Ran it up and it was smooth as glass, like a new motor (I was wearing that sh*t-eatin' grin all night!!!). Took it out the next day with a buddy to set the WOT timing (smooth as glass and running @ 5300 rpm) and it ran perfectly.....for a while. The intermittant running poorly, sputtering, idle came back. I had the timing light and checked the idle again an found it jumping around. I grounded the quickstart lead and it evened out. It also did the SLOW thing again once, for a brief moment, like the feature was switching on and off quickly, and then didn't do it again. The temp gauge still read cool.
Now, with all that done, this is what I'm thinking and I'd love some input. As for the idle issue, it's all electrical. The fuel system is perfect and it runs so smoothly and quietly until it has the problem, which seems to turn on and off like a switch. I also notice when it does act up, the motor is louder with a throaty sound, and the idle is higher. I'm guessing the quickstart is not disengaging and/or kicking in when it's not supposed to. The SLOW issue is new and also intermittant. That would leave it to be a bad powerpack (quite possible, given the purchase) or the temp sensor. I pulled both sensors and tested them with heat. The starboard kicked in @ 165deg and the port kicked the quickstart @ 125deg but the tan lead didn't register until much higher than the 165 of the starboard. It didn't seem to trip at first but eventually did trip though, and my thought would be if anything, it wouldn't be an issue for the idle problem unless it kicked in much lower. I also checked the diode in the tan lead, working fine. I'm leaning towards the new powerpack as the trouble. I purchased finally a DVA adaptor from mastertech (great guys!) and made some tests last night. The adaptor didn't really have much for instructions, but my understanding is that you connect it and set the meter for DC volts. My fluke is digital and auto ranging. I tested using the figures from rapair.com and found the timing base to be well within specs but found some discrepencies with the stator and powerpack:
brwn to brwn/yel: 588 ohms disconnected, 90 volts connected, (should be
950-1100 ohms and 150v- the chart for motors without
quickstart shows 450-550 ohms and 150v)
orng to orng/black: 96 ohms and 17-20v connected or disconnected (chart
shows 93-100ohms and 150v)
orange leads to coils to ground: 175-178volts on all, also, strong blue spark
on all cylinders.
Given these readings, it appears as if the stator is not putting out enough juice, but the spark is very strong and consistant. I assume I'm using the DVA correctly, please let me know if I need to set it differently. I'm going to take her out today and rig it so I can switch off the temp sensor leads for the quickstart and SLOW to see if I can isolate the problem to the sensor or powerpack.
Thanks for any of you who stuck through this long post, and for any input you might have! I think this motor has the potential to be very strong and reliable but it came to me with multiple issues, mostly stemming from some sloppy work. I've eliminated nearly all with lots of help and insight from here, now I can see light at the end of the tunnel.
Evan