04300exc 2 Posted September 5, 2022 Hey guys - first time here - working on my 1995 Honda foreman 400...it has no spark. During the diagnosis, I get continuity from the green wire in the 5P connector from the stator to the yellow wire in the 4P connector plug at the ICM.... so basically the yellow wire is grounding out. If I disconnect the rectifier connector plug, the yellow wire at the 4P ICM plug is no longer grounded.... but still no spark to plug if rectifier connector is unplugged. so.... does rectifier have to be plugged in for spark at plug?? This is the only thing I have found - ran a lot of diagnostic checks, and everything seems to check out ok - the stator itself, when unplugged seems to test ok, but I have read that sometimes they can still be bad??? I have replace ICM and Rectifier..no luck. Any advice is greatly appreciated. Also, I did try to check AC voltage from yellow stator wires by just cranking engine.... but did not know how much voltage I should see on my dvm. Share this post Link to post Share on other sites
jeepwm69 7,600 Posted September 7, 2022 Welcome aboard. I'll let @AKATV, @retro, or @Melatv take this one. Whenever I see "no spark" I immediately jump to CDI issues, but they understand the voodoo that is electrical stuff much better than I. Share this post Link to post Share on other sites
AKATV 820 Posted September 7, 2022 (edited) The rectifier has to be plugged in or you will get no spark A bad rectifier (voltage regulator) will also cause no spark Are you sure the rectifier is good? It sounds to me like to have a bad/shorted diode in the rectifier due the fact the short goes away when you unplug the rectifier. Edited September 7, 2022 by AKATV Share this post Link to post Share on other sites
04300exc 2 Posted September 11, 2022 Running again! Thank you for your help. I ended up replacing the rectifier, CDI box, and new coil - now I am trying to resolve fan problem. 1 Share this post Link to post Share on other sites
shadetree 5,880 Posted September 11, 2022 55 minutes ago, 04300exc said: Running again! Thank you for your help. I ended up replacing the rectifier, CDI box, and new coil - now I am trying to resolve fan problem. fan is bad ?, fuse is blown ?, bad oil temp sensor switch ?, or the fan control unit is bad ?. Share this post Link to post Share on other sites
04300exc 2 Posted September 11, 2022 Initial symptoms: no fan, no oil light when first turn on key. I hot wired fan..it's good. I repaired wire to sensor switch... but still no light or fan. Replaced fan control unit (FCU) and sensor switch....if I ground the sensor wire, the fan turns on, but I still have no oil light ( all oil light wires check out fine, bulb is good...its not getting a ground signal from new fan control unit)....interesting, I replaced the new FCU with the old one again...and oil light will come on for a couple of seconds, but with old FCU when I ground the sensor wire, the fan will not come on. My speculation is that the new FCU (china) does not operate exactly the same as the OEM. I ran the machine at idle for several minutes, but could never get hot enough to get fan to turn on. My laser temp gun reads just over 200 def F at engine case. I am hoping that driving the machine today and getting it hotter will activate fan....but again, no oil light when first turning on key. 1 Share this post Link to post Share on other sites
Goober 1,555 Posted September 11, 2022 (edited) If no oil light or steady oil light or flickering oil light I’d say FCU. As a diagnostic i heat mine in an oven for 3 hours at 200F. This usually revives them long enough to get a new OEM AKATV heats them in an oven for 5-7 minutes at 450F and says this is Usually successful fan should come on after engine gets to 212F;100C. Depending on rate of heating you might get to 220F before fan comes on. Much over that and you’re getting out of spec Edited September 11, 2022 by Goober Share this post Link to post Share on other sites
