Re: 1990 120 evinrude powerpack
I assume that when you say "I put the new pack on checking with plugs out and grounded 1 2 3 are firing fine but 4 is not fireing steady", you are checking the spark by having the spark plugs connected, then grounding the side of the spark plug to the powerhead block?<br /><br />If so, that spark check is improper and will not result in true results. The spark must be tested with the spark plugs removed, with a spark tester whereas a spark jumping gap of 7/16" can be set. There's a few home made spark testers listed on this site so you can simply make a search and they should show up.<br /><br />If memory serves me correctly, the timer base assy has two sensors on that model, one firing the starboard bank, the other firing the port bank. Since you do have spark on at least one cylinder of each bank, you can consider the timer base assy to be fine.<br /><br />However, it is quite possible that one of the Pins or Sockets leading from the timer base to the powerpack is dirty, has been pushed back somewhat so that it is not making a good connection, or has a frayed wire at the connection point to the pin or socket or at some portion of the length of wire.<br /><br />Check to see that the timer base moves smoothly from the idle (retarded) position thru to the full spark advance position without sticking.<br /><br />The stator on that model which is the beginning of the charging and ignition system is either a 3amp or 9amp model, and it's unlikely that it would get hot enough to melt down. But, it does happen, especially if the engine has been run with a faulty rectifier. Should a melt down take place, that would result in a AC voltage drop to the powerpack, in turn resulting in erratic and eventually no ignition. A melt down is usually obvious as the stator would have cracks and a sticky substance dripping down on the timer base area and the powerhead.<br /><br />Carburetors..... Did you dismantle them completely, then manually clean all of the jets with a piece of mechanics solid strand wire? If not, do so as just soaking the jets (most of the time) really doesn't get them thoroughly clean. Installing complete new carburetor kits is a must. The float should be set (with the carburetor held upside down) so that the free end of the side view is ever so slightly higher than the hinged end, and level when viewed at the end view.<br /><br />Are you sure you installed all of the jets exactly where they belong?<br /><br />Timing.... unless you know exactly what you're doing, I'd suggest you spurge a few dollors at a dealership and mechanic you trust to have that set exactly where it belongs. A few degrees too far advanced and you'll melt a piston, a few degrees retarded results in a power loss and a condition most technicians refer to as "coking" (coke-ing). Coking causes a vast built of of a waxy looking substance between the piston top and the cylinder head.... vast meaning something like a coffee cup full.<br /><br />The Champion QL77JC4 plugs, according to the manual are to be set to .030, however for many years the factory recommended gap was .040. When all is as it should be, you might want to try both gap settings for comparison.<br /><br />Soooo..... That should keep you busy to at least noon time (grin)
