nwboater45
Petty Officer 3rd Class
- Joined
- Sep 6, 2012
- Messages
- 91
From fixing one problem to the start of a new problem. I just got done replacing the exhaust shutters on a motor that probably hasn’t had them in years (see previous post). Anyways I have a 1989 470, 3.7L, 165hp motor that has decided now to backfire, cough and sputter upon shut down. I runs and idles fine while on muffs. I had rebuilt the carb last year along with installing electronic ignition. Before installing shutters I never had this problem.
Over the weekend I purchased and gapped new spark plugs, (wires, cap, and rotor are all fairly new). I located TDC using the finger test and set the rotor to the #1 plug. I also redid the settings on the carb (adjusting the idle screw to 1 ¼ turns past light seating and throttle screw to 2 turns past just touching). I started it up and ran it until it got warm. I put the timing light on it and adjust the timing to 4 degrees. I then put on my Acutron to adjust the rpm which I adjusted the throttle screw until I reach 600 rpms (which now puts the timing at about 8 degrees). It seems to idle fine and has no hesitation throttling it up to about 1,000 to 1,200 rpms. But when I turn the ignition key off it sputters and coughs about 4-5 times before shutting down. I have looked through the forums and could not find anyone else with this problem. Any suggestions on where to start? Is my timing out of wack? Could it be fuel still pumping into the carb?
Thanks.
Over the weekend I purchased and gapped new spark plugs, (wires, cap, and rotor are all fairly new). I located TDC using the finger test and set the rotor to the #1 plug. I also redid the settings on the carb (adjusting the idle screw to 1 ¼ turns past light seating and throttle screw to 2 turns past just touching). I started it up and ran it until it got warm. I put the timing light on it and adjust the timing to 4 degrees. I then put on my Acutron to adjust the rpm which I adjusted the throttle screw until I reach 600 rpms (which now puts the timing at about 8 degrees). It seems to idle fine and has no hesitation throttling it up to about 1,000 to 1,200 rpms. But when I turn the ignition key off it sputters and coughs about 4-5 times before shutting down. I have looked through the forums and could not find anyone else with this problem. Any suggestions on where to start? Is my timing out of wack? Could it be fuel still pumping into the carb?
Thanks.