Cutting out at mid rpms

[Mark Veal]

1998 350 MAG MPI. My engine acts like it is not firing on all cylinders from 2k to 3k rpms. Starts perfect, great above 3k. But it does not do it all the time. Some days no problem at all, some days first power up. Acts like a timing points spark advance problem but I have electronic ignition. Started three years ago in the middle of a three hour run. Has not gotten any worse. Could this be a snap-back problem.

 

[Bski]

Re: Cutting out at mid rpms

Mark, have you checked the timing to see if it's advancing when you rev it up? Put a timing light on #1 and watch the indicator, it should advance as you rev the motor. Also look for any vacuum leaks, easy way to find them around the carb is spray some carb cleaner around the base etc. while it's running, if there is a leak you will notice a change in the idle. Last of all make sure your wires and dist cap are in good condition, no cracks. I like to do this the unconventional way but putting my hand in there while it's running and I get a nice shock. I don't recommend this method cause it can be dangerous. Another good way is to look at the motor in the dark while it's running and if there is a bad wire or crack in the cap you will see the arcing of the spark.

 

[tommays]

Re: Cutting out at mid rpms

if the ingition checks out my engine runs like this when its time to replace the water sepator filter starts perfect midrange break up<br /><br />tommays

 

[Mark Veal]

Re: Cutting out at mid rpms

Thanks. I bought a new cap & rotor but have not taken it out yet as it is 5 hours to the river. I read a post about "snap back" and was thinking based on how the motor sounds that my timing advance is sticking. There is visable rust in the distributor. How do I lubricate this area.