Hi Everyone,
Sorry for the lengthy post - I'm trying to include all relevant info. I have a new-to-me 1996 Mercruiser 3.0LX mounted in a Starcraft Islander. The engine serial number is OF556055, and the ignition is an EST ignition. The boat started and ran fine on muffs, but a few weeks ago on our first trip out (of course!) the engine stopped running abruptly an hour into the trip. Plenty of fuel in the tank, and fuel can be seen squirting into the carb. Prior to the engine quitting, the tachometer began behaving erratically despite no actual change in engine RPMs. The tach needle would bounce, and settled out at about 3,000 RPM. The engine was running about 1800 RPM prior to the erractic tach. The engine quit very suddenly, as if the key had turned off.
I got towed to a friendly dock, and had limited parts available locally. Prior to the trip the boat had a new distributor cap, rotor, wires and plugs, and also a new ignition module on the distributor. This was all done by the prior owner.
The engine was showing no spark with an in-line spark tester on the #1 plug. I thought the coil was an easy try, so I sourced one locally for a GM car. It did not have the correct mounting bracket, but the electrical connections appeared to be the same. This did not fix the issue. A google search indicated I might try unplugging the tach. Also no change. I began working my way done the line - the ignition switch checked out fine with a test light. I could not get the deadman-style kill switch to pop out from the Quicksilver 3000 Classic control. However, after monkeying with that the engine appeared to sputter upon trying to start. I put the throttle at wide open, and the engine did start but was running rough. Appeared to be running rich by the smoke in the exhaust (black, not blue or white). However, seemed to run ok at higher RPM once it warmed a bit, so was able to get to the boat launch under its own power. Stalled upon shifting to neutral to coast into the dock, and wouldn't restart.
Got it home. Put the old coil back on, and left the tach unplugged. Boat started beautifully. Plugged tach in (I have easy access to the back of the instruments via an access panel from the cabin side), restarted and appeared to run rough again. Unplugged tach, started great. Plug tack back in, and it started great once again. In other words, not perfectly repeatable with tach plugged in/unplugged. Tach behaving normally when plugged in.
Does this crowd have some thoughts? Would a shorted tach produce an intermittent problem like this? Or, do I more than likely have a few concurrent problems..?
Thanks in advance!
Sorry for the lengthy post - I'm trying to include all relevant info. I have a new-to-me 1996 Mercruiser 3.0LX mounted in a Starcraft Islander. The engine serial number is OF556055, and the ignition is an EST ignition. The boat started and ran fine on muffs, but a few weeks ago on our first trip out (of course!) the engine stopped running abruptly an hour into the trip. Plenty of fuel in the tank, and fuel can be seen squirting into the carb. Prior to the engine quitting, the tachometer began behaving erratically despite no actual change in engine RPMs. The tach needle would bounce, and settled out at about 3,000 RPM. The engine was running about 1800 RPM prior to the erractic tach. The engine quit very suddenly, as if the key had turned off.
I got towed to a friendly dock, and had limited parts available locally. Prior to the trip the boat had a new distributor cap, rotor, wires and plugs, and also a new ignition module on the distributor. This was all done by the prior owner.
The engine was showing no spark with an in-line spark tester on the #1 plug. I thought the coil was an easy try, so I sourced one locally for a GM car. It did not have the correct mounting bracket, but the electrical connections appeared to be the same. This did not fix the issue. A google search indicated I might try unplugging the tach. Also no change. I began working my way done the line - the ignition switch checked out fine with a test light. I could not get the deadman-style kill switch to pop out from the Quicksilver 3000 Classic control. However, after monkeying with that the engine appeared to sputter upon trying to start. I put the throttle at wide open, and the engine did start but was running rough. Appeared to be running rich by the smoke in the exhaust (black, not blue or white). However, seemed to run ok at higher RPM once it warmed a bit, so was able to get to the boat launch under its own power. Stalled upon shifting to neutral to coast into the dock, and wouldn't restart.
Got it home. Put the old coil back on, and left the tach unplugged. Boat started beautifully. Plugged tach in (I have easy access to the back of the instruments via an access panel from the cabin side), restarted and appeared to run rough again. Unplugged tach, started great. Plug tack back in, and it started great once again. In other words, not perfectly repeatable with tach plugged in/unplugged. Tach behaving normally when plugged in.
Does this crowd have some thoughts? Would a shorted tach produce an intermittent problem like this? Or, do I more than likely have a few concurrent problems..?
Thanks in advance!
