3.0 mercruiser bogging under acceleration

[joseph1980]

I've got a 2000 mercruiser 3.0 with the delco est. the boat seems to idle fine without any issues. upon accelerating the motor bogs and clatters, very similiar to what a motor that has detonation sounds like. while this is going on or shortly thereafter the tach starts bouncing erratically while under load. upon returning back to idle the needle will calm down and stop bouncing. so far i've replaced everything ignition wise minus the coil and the sensor under the distributor that connects to the ignition control module. i took it to a mechanic would was unable to diagnose. he said the base timing was correct. am i right to assume this is ignition related? would the coil be the likely culprit?

[Black as]

I would of thought the "mechanic" would of given you some idea of what's wrong.

[Bond-o]

Ayuh,.... Probably Crap in the carb, causing a Lean condition...

[ENSIGN]

Clogged up accelerator pump circuit.Time for a carb rebuild and check the gas.

[joseph1980]

carb was soaked and rebuilt and was of no help fresh gas was placed 2 weeks ago with no help in the above symptoms. and what would the carb have to do with the tach bouncing?

[fat fanny]

If the mechanic checked the base timming did he check the timming for proper advance? If not you could have a ign, module issue not allowing it to advance correctly! If that be the case make sure you buy AC Delco OEM mod all others are a waste of money and time. Have you also checked the compression #'s on all your cylinders lately? I had this issue just 3 weeks ago and it ended up being a blown head gasket.

[Rocky_Road]

Here is Mercruiser's answer to a 3.0L bogging down:



This is assuming that the engine timing is correctly set at base timing (not every mechanic knows the correct steps for this), and the timing advance is working properly.

Happy boating!

[joseph1980]

compression test shows 160 across the board...i may try any bypass the water seperator/filter i put on and see if that makes a difference