Mercruiser 888 (Ford 302) Stalls at 3000 rpms

[jabroni]

So I purchased an 1973 Century Raven with a Mercruiser 888 I/O (Ford 302) and ran fine the first few outings. Soon after it started stalling around 30 seconds after getting on plane around 3000 rpms. It was hard to start but eventually stalled again. We creeped back to the dock around 1000rpms, but slowly they started to drop and soon sputter and stall when it got down to 800 rpm. Would not start unless left for 10 mins. Again, and again I followed this till we got back to the dock. The next day, I tried to trouble shoot the problem, but it would not start at all. I thought that it was a fuel problem, but can easily see gas spray into the carb. and also tried my trusty can of starter fluid. I gave the boat a full tune-up, replacing plugs, wires, coil, distributor cap, points, condesor, fuel filter/water seperator, battery and everything else I could think of. Re-tuned the carb., and filled it with fresh fuel. Still, same problem. The carb is a 2 barrel marine carb from holley and looks like it was replaced not too long ago. I dont know what else to check. I tried the many safety kill switches but they all seem to operate correctly. I have heard of this problem before with other boaters on this forum but have yet to really find a solution, others believe it could be a bad tach., timing advance is offset, fuel pump, and breather valve. I am really unfamiliar with these and could use some advice. Please help. Thanks!

[kenJ]

Not sure why a bad tach would cause the engine to run poorly. Fuel pump not up to specs? Fuel tank vent line plugged? Sucking air into fuel system. Fuel tank pick up tube getting blocked by crud in the bottom of the tank or positioned wrong. Vapor lock caused by a fuel line getting too hot. If you have ruled out the spark issue by replacing everything then it must be in the fuel system somewhere.

[gonzo]

Is there power getting to the coil? Try a jumper wire directly from the battery

[powerabout]

Bad Tacho can definately stop the engine as its conected to the points side of the coil on that engine.
There is a filter in the fuel line where it goes into the carb, but I assume was cleaned if the carb was replaced.
If water went through the fuel system the fuel pump can corrode as it has a low spot that will hold the water.
The rotor button can also play up on those. I have replaced a few with problems as its not something you normally see.
The ignition does have a ballast resistor block but it is a wire built into the wiring loom on the engine, so a good test ( as mentioned above) is to jump the power to a B+ and see if it helps.