1990 Johnson GT150 on a 1984 Ranger 350V
Model: J150STLESB Serial: 08594609

This has I believe been an issue since I purchased this boat 2 years ago and have been trying to figure it out. I will do my best to explain it but if you have any questions I'll do my best to answer and I can perform any inspections or operations with some guidance. Anyway the engine since I purchased it has ran fine on muffs out of the water but when I put it in the water it will die almost immediately off the trailer (I've now decided I believe that is because I trim it down) but then I could get it to restart and run around the lake for as long as I would like but once I put it into neutral and let it get back down to idle it dies and will not restart. I recently got the tach functioning again (the regulator was faulty) and the idle with the engine trimmed all the way down on muffs was maybe 500 RPM and from what I've read they will lose ~150 RPM in the water because of the back-pressure so I can see why that would stall it out. I have now raised the idle to ~1000 with the motor trimmed all the way down, but then I noticed that as I trim the motor up it will pick up RPM, roughly 2000-2200 right around when it gets out of the fine trim adjustment area, then it got all the way up to 3500 RPM when I had it trimmed nearly all the way up before I trimmed it back down to control the RPM increase.

Work I have performed includes new fuel and oil lines (and bulbs), spark plugs, carb rebuild on all three, and the most recently replaced voltage regulator. The engine is still using a VRO system, I can't think of anything else relevant but I'm happy to answer any questions. This may be normal but it just seems odd, this is my first outboard.