Sputtering/Backfiring Under Load

backfoot100 wrote: Jared, nice to hear it ran good for you. From other posts I've seen from you, I don't know that you're running too rich. Do you get black smoke when you start it or when you're idling? Your plugs look just like mine used to when I lived in the north and would run the boat for 10-15 minutes at idle to warm up before changing the oil when I was winterizing it. Then I would pull the plugs to fog the cylinders and they all looked just like yours. You gotta open that sucker up!!!! Do a couple barefoot runs and pull the plugs and I'll bet they look totally different. You can do a search for setting the idle mixture to adjust that, but I think the carb is OK. You should definitely look at replacing the old springs with the springs in the EI kit though. That would be first. If you have any additional problems, I would change out the coil first thing. When I put my MSD setup in my boat, the old coil only lasted a week or two. Enjoy the moment!

I am really just guessing, but I am geting smoke at idle. I was told by a mechanic that it was running rich. I am pretty sure it is. It may just be at idle, but I am not sure. I should try that idle adjustment procedure, see what happens.

Regarding the coil-- right now the old stock coil is in there. I have a brand new coil from SkiDim, but it is the stock replacement. I originally wanted to ship it back and exchange for "electronic ignition coil" (1.5 ohm) at SkiDim, but I am not sure I need to.

As I said before, the electronic ignition conversion instructions recommend a prestolite 5-69 coil. I think that is 1.5 ohms. The stock "points coil" replacement I got from SkiDim measures at 1.7 ohms (as does the one that is in the boat), so returning it may not be necessary. Besides, I think most people just use the stock coil (bypassing the ballast resistor, of course)

I was planning on calling prestolite to ask, but their website said they sold the distributor business. I haven't tried to call the new company yet. I probably should, I don't want to fry the new module.

But I will definately try and fix the advance.   I need to find a detailed explanation for taking the advance apart, replacing the springs, and lubing it up.

Jared

Jared, what color is the smoke you are seeing at idle? White (or light blue) is oil burning. Black is overly rich. Also as stated earlier in this thread, you can't depend on a plug reading that came out of an engine that was just ran at idle for several minutes. The plugs in your picture are also too cold for this engine. And then there's your timing advance issue. I'd get all of these items taken care of, then take your boat to the lake.... run it at cruising speed for about a minute, shut it down (immediately after cruise - no idle), change the plugs and save the ones you pulled for a plug chop. With your new plugs, finish your day on the lake and have fun. When you get home (or when you have time) cut the plugs open and look at them. You may just have your problems solved. Brian

nuttyskier2002 wrote: Jared, what color is the smoke you are seeing at idle? White (or light blue) is oil burning. Black is overly rich. Also as stated earlier in this thread, you can't depend on a plug reading that came out of an engine that was just ran at idle for several minutes. The plugs in your picture are also too cold for this engine. And then there's your timing advance issue. I'd get all of these items taken care of, then take your boat to the lake.... run it at cruising speed for about a minute, shut it down (immediately after cruise - no idle), change the plugs and save the ones you pulled for a plug chop. With your new plugs, finish your day on the lake and have fun. When you get home (or when you have time) cut the plugs open and look at them. You may just have your problems solved. Brian

I would say my smoke is black. Not white.

The plug chop procedure sounds like a pain. Sitting on the lake changing plugs doesn't sound that fun.

I may have to build up to that.

Jared

Jared, did you resolve your issues with the EI? I just installed one and have very similar problems. A miss under load, mostly at mid-rpm's. See my post under Engine - Trouble after EI install. Did you ever replace the coil? Where did you end up on your timing?