Recently picked up a Ranger 360V with a Mercury XR2 150HP (serial 0A994384).
Idle was set at the mechanic shop to 1,000RPM which he said was high but engine didn't seem to want to idle much lower than that. He was concerned lowering it much more it wouldn't stay running. Otherwise, engine idles smoothly with no misses.
When I try to plane out things get interesting. There is strong immediate power but as you approach the 3,000+ RPM range the engine starts to sputter and miss some (but keeps running). Once on plane I can normally trim up some and throttle back (about 85-90% throttle) and everything seems to be running smooth. It really reminds me of hitting the rev limiter in a car and it momentarily slowing the fuel flow.
Top speed so far has only been around 24 MPH but I think this boat/engine combo should easily be twice that. Same with the RPMs.
Things already done (I'm assuming correctly):
- Mechanic set the timing & carb sync
Things I don't think it is... (feel free to disagree but provide rationale please)
1) fuel pump ... I was messing with the fuel selector and when I turned it to off the pump basically compressed the primer bulb due to vacuum pressure; so it seems like the pump is healthy
2) spark plugs (as I just changed them)
3) prop issues (I made sure the prop nut was tight and prop is not damaged; size is appropriate for the motor/gearing)
4) clogged carbs -> the bottom one was rebuilt and I believe the other two were examined; and idle is smooth; normally idle is the hardest thing when carbs are an issue.
5) oiling issues (I premix and not using the oiling system; it's disabled)
6) overheating... the tell tale flow is strong and consistent; motor never dies at idle or long runs indicating overheating
I've heard this could a number of things I could try...
1) a faulty neutral safety switch; try disconnecting it and see if the problem goes away; apparently 3000RPM is the magic number
2) bad stator (not sure how to test this) and/or trigger
3) adjust the idle (allegedly there is only 1 screw to adjust)
4) adjust carb link (it seems like at 100% throttle the throttle plates may not be 100% open IE perpendicular to the carb) and/or turn idle down to around
5) spray fuel into the carb running WOT and see if the engine bogs or RPMS increase. If it bogs running too rich and if it picks up running too lean
6) check the plug wires for resistance (bend wires to see if resistances changes indicating worn wires)
7) ??? Other ideas?
Any thoughts of things to test/look at/how to test would be appreciated. I like to be a little more practical than just throwing parts at things.
Idle was set at the mechanic shop to 1,000RPM which he said was high but engine didn't seem to want to idle much lower than that. He was concerned lowering it much more it wouldn't stay running. Otherwise, engine idles smoothly with no misses.
When I try to plane out things get interesting. There is strong immediate power but as you approach the 3,000+ RPM range the engine starts to sputter and miss some (but keeps running). Once on plane I can normally trim up some and throttle back (about 85-90% throttle) and everything seems to be running smooth. It really reminds me of hitting the rev limiter in a car and it momentarily slowing the fuel flow.
Top speed so far has only been around 24 MPH but I think this boat/engine combo should easily be twice that. Same with the RPMs.
Things already done (I'm assuming correctly):
- Mechanic set the timing & carb sync
Things I don't think it is... (feel free to disagree but provide rationale please)
1) fuel pump ... I was messing with the fuel selector and when I turned it to off the pump basically compressed the primer bulb due to vacuum pressure; so it seems like the pump is healthy
2) spark plugs (as I just changed them)
3) prop issues (I made sure the prop nut was tight and prop is not damaged; size is appropriate for the motor/gearing)
4) clogged carbs -> the bottom one was rebuilt and I believe the other two were examined; and idle is smooth; normally idle is the hardest thing when carbs are an issue.
5) oiling issues (I premix and not using the oiling system; it's disabled)
6) overheating... the tell tale flow is strong and consistent; motor never dies at idle or long runs indicating overheating
I've heard this could a number of things I could try...
1) a faulty neutral safety switch; try disconnecting it and see if the problem goes away; apparently 3000RPM is the magic number
2) bad stator (not sure how to test this) and/or trigger
3) adjust the idle (allegedly there is only 1 screw to adjust)
4) adjust carb link (it seems like at 100% throttle the throttle plates may not be 100% open IE perpendicular to the carb) and/or turn idle down to around
5) spray fuel into the carb running WOT and see if the engine bogs or RPMS increase. If it bogs running too rich and if it picks up running too lean
6) check the plug wires for resistance (bend wires to see if resistances changes indicating worn wires)
7) ??? Other ideas?
Any thoughts of things to test/look at/how to test would be appreciated. I like to be a little more practical than just throwing parts at things.
