Clois: For complete MSD troubleshooting go to
www.msdignition.comhttp://
(nice post huh???) Click on "trouble shooting". Check all your connections, if you determine spark is ok then check for fuel, maybe float levels are too high, you mentioned off road needle & seats these are intended for Jeep type applications and unusual angles of climbing such as rock crawling. Maybe your pump is pushing fuel past them??
The heavy 10 gage red from MSD box should be connected to the starter solenoid not through a fuse panel. The small (16/18 gage red wire) goes to a switched 12 volt source. Just a thought....if your fuse box is uncovered (open to the elements??) make sure you dont have corrosion on the contacts of the fuse in question if you are running it (small 16/18 red wire) through the fuse box. Humidity can play havoc for you guys that live in it, fortunately out here it is not that big of a problem.
BTW: For best results your fan should be run through a relay. You may be overloading the contacts in your ignition switch, running the MSD, Fan and other accesories through the switch??
Rick