camper4lyfe
Cadet
- Joined
- Sep 9, 2010
- Messages
- 18
I've got an '87 Merc 165 (the in-line 4) that's giving me a bit of a problem. It's been rebuilt a couple times, the most recent being crank and lower rod bearing replacement (turned the crank as well). When we put it back together, we ran it for a couple hours last Fall, just before storing it. We got it out of storage last week, cleaned it up, and it started right up and idled no problem. When we launched the boat, my wife (driving the boat, I was in the car) reported problems of the boat stalling once right after launching, as well as surging when she got back to the dock.
We took it for a long ride yesterday and ironed out a few more details. It'll start and idle great. Navigating around the docks at idle and in gear, the boat's fine. Once you bring it up off idle, it coughs and hiccups. Sometimes it stalls, sometimes if you give it a little more gas it'll "catch up" with itself and keep running. Once it hits 2000 RPM it runs like a top again. If you idle down coming into the doc, it'll stall out. Restarting it at idle resolves the problem and you're back to it idling fine and running in gear fine, so long as you don't bring it off idle.
We're thinking maybe there's some water in the gas, but after running it that long, you'd think it would have cleared itself out.
Another thing we noticed, that may or may not be related, is that we were cruising at 3000 rpm when I looked at the tach and it read 4500, though the engine speed hadn't actually changed. One theory is that the tach is bad, and it's causing a grounding issue. Points and condenser were changed after the 1st rebuild. We're also thinking maybe the points are just corroded and that's causing an issue.
Any thoughts or suggestions are greatly appreciated!
We took it for a long ride yesterday and ironed out a few more details. It'll start and idle great. Navigating around the docks at idle and in gear, the boat's fine. Once you bring it up off idle, it coughs and hiccups. Sometimes it stalls, sometimes if you give it a little more gas it'll "catch up" with itself and keep running. Once it hits 2000 RPM it runs like a top again. If you idle down coming into the doc, it'll stall out. Restarting it at idle resolves the problem and you're back to it idling fine and running in gear fine, so long as you don't bring it off idle.
We're thinking maybe there's some water in the gas, but after running it that long, you'd think it would have cleared itself out.
Another thing we noticed, that may or may not be related, is that we were cruising at 3000 rpm when I looked at the tach and it read 4500, though the engine speed hadn't actually changed. One theory is that the tach is bad, and it's causing a grounding issue. Points and condenser were changed after the 1st rebuild. We're also thinking maybe the points are just corroded and that's causing an issue.
Any thoughts or suggestions are greatly appreciated!