Xray4
Cadet
- Joined
- Apr 22, 2020
- Messages
- 29
Hi there, I have a new to me Johnson 150 2001, J150PLSIF looper OIS which has a rough/low idle, and low WOT RPM. Do you have any suggestions? Below are the things I've done..
When I got it, I had a new VRO fuel/oil pump installed. Ran great, idled great, during Quickstart had about 1100 RPM, then dropped to 850 RPM. At WOT, I had 5250 with a 14.5x17 prop.
One day, like a switch was flipped I had rough idle and only 4700 at WOT. Since then I've checked and done the following, and still only have 4900 RPM at WOT, and I don't know what else it could be.
Compression is good at 115-120. Heads haven't been cracked open yet but all plugs equally browned/oiled appropriately. No evidence of water on plugs.
Bypassed tank and ran from aux tank, no change
Ignition system:
Replaced with new: Stator, Powerpack, OIS sensor, primary and secondary plug wires, new Champion 78YC plugs at .030, new coils, no change
Rebuilt carbs with all new floats, gaskets, needles/seats, new bowls (old were warped). Timing has not been touched during my tests/rebuild. At WOT, butterflies are fully open, everything moves together. Timing stops advancing around half throttle, I hear this is appropriate.
I did notice that the throttle linkage at the motor appears to be maxed out, and the trunnion cannot be turned. I hesitate to try to free it because I'd need to use pliers, I worry I'll break it. It's one of the last things I can think of at this point. (photo attached). Also, Throttle control at helm looks like it could keep going but doesnt, in reverse it hits the bottom of control box, but in forward it stops about an inch from the end, but still butterflies are fully open so maybe this isn't it.., does it look right in the photo?
Idle screws were set at 10.5 turns! I think this is crazy high, but it used to run great at that... I reset idle screws to 4 turns per spec during carb rebuild and could not keep it idling. So, I went up to 7 turns and I can now idle well in the water, in gear, at about 550-650 RPM, feels and sounds like it wants to quit any moment but it doesnt. Still can't get over 4900 RPM at WOT.
I can turn the idle screws back up to the 10.5 turns they had before, but I didn't think that would affect WOT?
I'm fairly confident I don't have a spark issue or fuel issue according to all the new/rebuilt and checked items. Manually choking air to each carb has the desired affect, manually spraying fuel into throats has the appropriate bog down affect on each. Can't single out a single carb that could be bad.
I cannot find an OEM manual, can't figure out which one it is, and where to get one. I have a crappy SELOC. I don't trust it to do a link and sync, but again, nothing there was changed between the time it ran fine to the time it started doing this. Maybe someone has the procedure for this exact model? (Local mechanic says it shouldn't need a link and sync since it wasn't touched.)
At this point, I am on a 4 week waitlist to get it on a dyno at local Johnson/Evinrude shop.
I'm stumped. I'm hoping someone here has some ideas?
When I got it, I had a new VRO fuel/oil pump installed. Ran great, idled great, during Quickstart had about 1100 RPM, then dropped to 850 RPM. At WOT, I had 5250 with a 14.5x17 prop.
One day, like a switch was flipped I had rough idle and only 4700 at WOT. Since then I've checked and done the following, and still only have 4900 RPM at WOT, and I don't know what else it could be.
Compression is good at 115-120. Heads haven't been cracked open yet but all plugs equally browned/oiled appropriately. No evidence of water on plugs.
Bypassed tank and ran from aux tank, no change
Ignition system:
Replaced with new: Stator, Powerpack, OIS sensor, primary and secondary plug wires, new Champion 78YC plugs at .030, new coils, no change
Rebuilt carbs with all new floats, gaskets, needles/seats, new bowls (old were warped). Timing has not been touched during my tests/rebuild. At WOT, butterflies are fully open, everything moves together. Timing stops advancing around half throttle, I hear this is appropriate.
I did notice that the throttle linkage at the motor appears to be maxed out, and the trunnion cannot be turned. I hesitate to try to free it because I'd need to use pliers, I worry I'll break it. It's one of the last things I can think of at this point. (photo attached). Also, Throttle control at helm looks like it could keep going but doesnt, in reverse it hits the bottom of control box, but in forward it stops about an inch from the end, but still butterflies are fully open so maybe this isn't it.., does it look right in the photo?
Idle screws were set at 10.5 turns! I think this is crazy high, but it used to run great at that... I reset idle screws to 4 turns per spec during carb rebuild and could not keep it idling. So, I went up to 7 turns and I can now idle well in the water, in gear, at about 550-650 RPM, feels and sounds like it wants to quit any moment but it doesnt. Still can't get over 4900 RPM at WOT.
I can turn the idle screws back up to the 10.5 turns they had before, but I didn't think that would affect WOT?
I'm fairly confident I don't have a spark issue or fuel issue according to all the new/rebuilt and checked items. Manually choking air to each carb has the desired affect, manually spraying fuel into throats has the appropriate bog down affect on each. Can't single out a single carb that could be bad.
I cannot find an OEM manual, can't figure out which one it is, and where to get one. I have a crappy SELOC. I don't trust it to do a link and sync, but again, nothing there was changed between the time it ran fine to the time it started doing this. Maybe someone has the procedure for this exact model? (Local mechanic says it shouldn't need a link and sync since it wasn't touched.)
At this point, I am on a 4 week waitlist to get it on a dyno at local Johnson/Evinrude shop.
I'm stumped. I'm hoping someone here has some ideas?
