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Mercruiser 3.0 new engine est ignition

C

chuckberg2

New member
I'm new, so hello all, and please bear with me

My 3.0 came with distributor from factory, have set base timing by the book to 1 degree before TDC. runs totally as it should up to 3100 RPM then acts like it has points and they are breaking up.

Spark pick up coil Ohms out, replaced main coil same results, disconnected Tach.

when it starts breaking up have been over top of carb, still getting fuel

has anyone had this problem before?
 
You're supposed to ground a wire, to put the distributor timing at its base setting, before timing the motor. Did you do this?

Jeff
 
Thanks for the reply, yes I did, followed the procedure to a Tee, after more analysis and testing, i believe I have a valve problem, with a friend aboard we realized at 3100 RPM it was blowing raw fuel back up the carb, luckily no fire, will try a valve adjustment tomorrow, more to come.
 
Ayuh,.... On a brand new motor, I'm guessin' someone adjusted the valves, Waay to tight,.....
 
valves adjusted, , i adjusted too tight first time, readjusted to 1/2 turn after no lash, running a tad better, plan to check valve springs next to check for weak spring somewhere, along with leak down test.

Question, would the module at the base of the distributor create these conditions? but on second thought, we pulled the plug wires and were getting spark from each when it started breaking up.
 
Check your spark plug gap........that ignition is very sensitive to the gap...if too big it will create issues......
 
starts and runs fine up to 3200 RPM, no miss, no rough idle, no backfire.
Mechanical fuel pump, any chance it could be over pressurizing at high RPM and flooding out, that's why the fuel is pumping out the top of the carb in vapor?
Quitting on this today, every one thanks for all of your input.
 
Yeah, I did one, all cylinders came up even across the board, I cannot find my results written down though, may do another one just to be sure and have the record of it.
 
Installed new Plugs, ran great for probably a half hour, then started doing it again, taking back to engine distributor for warranty look see, I'm thinking either a rev limiter is programmed in the EST system or have either a faulty Module or spark pick up coil, both came new with the engine.
 
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