1995 350mag mpfi running rich

[cjay]

Please help. I can't figure out why my engine is running rich and plugs are getting black with carbon. After which engine runs rough and misses.

[3mk]

spark plug wires and dist cap are cheap and easy to check and change yourself

[cjay]

Did that already, and I replaced the water temp sender. My next guess is the map sensor.

[3mk]

I dont think there is a map sensor or are you tune port inj

[cjay]

yes it is a mpi engine. without a scanner I think I should just go to the dealer.

[3mk]

I hate the dealer there so expansev they charge 160 hr here

[chpthril]

Check the vacuum line to the MAP sensor, should have strong manifold vacuum on it. Since marine engines dont typically use a MAF sensor, they are a Speed-Density system, so manifold vacuum, engine temp, and TPS with be the main sensors to plot the fuel map.

You say temp sensor, are you sure you replaced the Temp Sensor for the ECM and not the temp pick up for the gauge? The ECU's sensor should be a 2 wire, the water temp pick up will probably be a single wire.

If you have a DVOM, all 3 of these can be tested without spending thew coin to guess.

[venetrex]

where are you

I have the scan tool, where are you located???