502 Mpi Problems Help!!!!!!!!
 

A friend has a 502 MPI. The motor is all fresh. Long story short the block and heads were froze and broke so everything is NEW. now to the Problem. The motor starts and runs perfect. It will only rev to about 3,500 rpm,s. I know about setting the timing with the jumper wire. We did that. For some reason it seams like it has a rev limitor. I was told by someone that a rev limitor was built in to the Ignition box in the distributor. Can anyone tell me if that is true on a MPI? Is it possible that the rev limitor is stuck?

The motor seams to run rich at idle. It starts up without any problem. We have been fooling with this for a couple weeks now. The local Mercuiser dealser's don't have a scan tool. Is it possible to turn off the rev limitor? Any HELP would be GREAT. Thanks in advance. Dan

it sounds like its in guardian mode which means it might have a sensor issue. but the bottom line is that without a scanner and or a factory workshop manual to tell you the test procedures and values, you are really wasting your time.

get a scanner from somewhere and the manual and you'll be able to fix it it 30 minutes. and yes... there are a dozen things to check first... bad connections, off connections , water temp too low, etc etc but the ecu is a smart little guy only as long as it gets the correct info from the sensor array. any one of the sensors being bad will cause the system to adjust it self out of range and kick it into guardian mode...

which sounds to me like where you are.

Agree 100% been there done that.