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Backfire!

Run with a timing light one cylinder at a time and observe the flashing of the light.----------What happens to the flash during the hiccup and is it the same on all 4 ??
 
I am telling you true.....you have #2 and #4 coils wired wrong (primary wires). You have not posted the results of my suggestion on post#29 to simply swap spark plug leads on 2 and 4, nor have you posted the answer to the question about head temps on the port side.

I know you said you checked the wiring....but how did you check it? Same way as when you put it together? And here is the kicker!!!! The Clymer manual wiring diagram is wrong.....Is that how you checked it?

Every symptom you list points to the swapped primaries on #2 and #4.

Just do my suggestion of swapping the plug leads, and post back.
 
Post the colour of each small wire from cd box to the coils.---They are orange with a stripe !--------Or post a close-up picture of each pair of coils showing this.------Take this one step at a time and you may find where the problem is.-------Testing and trouble shooting is the path forward!--as you have found buying parts gets expensive !
 
daselbee, I swapped the plug wire between Coils #2 and #4 and it started backfiring from the 1st turn of the key and wouldn't stay running for more than a second or two. I tried the same thing with coils #1 & #3 (just for grins) and it wouldn't even start.
racerone, wiring is as follows:
Solid orange wire from (port side) cd box goes to coil#2
Orange wire with blue stripe from cd box goes to coil #4

Solid orange wire from (starboard side) cd box goes to coil #3
Orange wire with blue stripe goes to coil #1
It's funny... when I first start this thing up it runs just fine. But it seems like after it warms up is when it starts to hiccup. I hooked the timing light to each wire seperately and watched it during the hiccups and didn't see any noticable difference from wire to wire. It almost seems like after it warms up, one on the cylinders is getting some sort of pre-ignition somehow. This thing has really got me baffled. I was really hoping daselbee had the answer by swapping 2 and 4 out, but unfortunately that wasn't the problem. I'm not sure where to go next.
 
Mark the flywheel with the cylinder # for " top dead center " for each cylinder.-----Run with timing light and see what it shows.
 
Goommer said:
Solid orange wire from (port side) cd box goes to coil#2
Orange wire with blue stripe from cd box goes to coil #4

Solid orange wire from (starboard side) cd box goes to coil #3
Orange wire with blue stripe goes to coil #1
Click to expand...


And again I POST....YOU GOT IT WIRED WRONG. The orange/blue goes to the top cyl, and the orange goes to the bottom.

You are using the Clymer color wiring diagram WHICH IS WRONG.
 
daslebee, I swapped the #2 and #4 wires (spark plug wires) coil#2 to spark plug 4 and coil#4 to spark plug 2 as you suggested; but as I stated in my earlier post it would backfire from the 1st turn of the key and wouldn't stay running for more than a few seconds. Am I missing something? Should I have swapped coils #1 and #3 as well?(at the same time?) I swapped 1 & 3 but I put 2 & 4 back like they were first (it wouldn't even start). I don't have the Cylmer manual, I just put it back together exactly as I took it apart (or at least I thought I did). The wire routing I described to racerone is how it's wired in the video.
 
One step at a time !!-------Mark the flywheel and run with a timing light.------Found wiring diagrams for your motor and the two wiring diagrams are different for the same ignition system.
 
Gentlemen. I am sorry for getting frustrated last night.

That said, there is only one way to wire the ignition primaries.
The orange/blue is the top cylinder on both sides, and the plain orange is the bottom cylinder on both sides.

Swapping the ignition primaries like he posted the current wiring arrangement will give him exactly the symptoms he is describing, and those shown in the videos.

If he has other faults, like timerbase to powerpack miswirings...etc, I don't know.

It is a known fact that the Clymer color wiring diagram is wrong regarding that system.

I will post the thread from iBoats that discusses this exact issue, where the Clymer manual is linked, and shows the error, if I can find it.

That's all I can say....get it wired right.
 
daselbee no need for apologies, I didn't take offense. (You guys are trying to help me) I'll be the first to admit that I make mistakes. I don't have a wiring diagram but I'm almost positive I put it back together exactly as I took it apart; but that's not to say that it wasn't wired wrong when I got it. Like I said, a friend of mine gave me this boat, he had someone wrench on it after he blew piston #3 and declared it "Toast" so I took it on as a project. I was very meticulous documenting everything when I took it apart with photos and hand drawn diagrams. Did the whole thing myself, machine work and everything (I own a machine shop).

So it looks like I should swap both 1&3 and 2&4 that would put orange/blue wire on top (both sides) and solid orange wire on bottom (both sides). Right?

I'm going to do racerone's suggestion of marking the flywheel at TDC of each piston using a dial indicator before I try swapping all the wires and watch each mark with a timing light, (like it's wired now) because this thing runs like a top (until it warms up). It'll only take me a few minutes then we'll (all) know where we're at.
I probably won't get a chance to do it till next week though, so bare with me...
 
There is a method to the madness of the color coding.

4 cyl engine.
Top cylinder is orange/blue. Bottom cyl is orange.

6 cyl engine.
Top cyl is orange/blue. Middle cyl is orange. Bottom cyl is orange/green.

Trim and tilt....testing only, two wire systems only.
For up, put blue on positive, and green on negative of battery.
For down, put green on positive, and blue on negative of battery.

So you see, blue is "sky" or up, and green is "grass" or down.

Four cyls dont have that extra two cyls, so they just stop with plain orange on the way down the cylinder bank.

Does this make any sense?

And to be truthful, I didn't even notice that #1 and #3 were wired opposite either.
I thought you only swapped #2 AND #4. So that explains why my "spark plud lead swap fix" did not work.

So, your firing order would have been, 3, 4, 1, 2. (I think)....and it should have been 1, 2, 3, 4.

The timer base detects the spinning flywheel, and signals the packs to fire 1,2,3,4.

I bet if you wire it right, you are good to go.
 
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Swapped wires are not the problem from what i see and hear in the video....thats not to say that the timing may not be out or a plug firing at the wrong time....i would leave the wiring as is and go with racers procedure....pay special attention to a possible plug firing at the wrong time....if all checks out then i would suspect carbon and pre ignition...
 
Well... daselbee was right all along, but I might add that it would have been very difficult for me to ascertain that fact had I not took racerone's advice by finding TDC for each cylinder and marking on the flywheel 1,2,3 &4. I hooked a timing light to each plug wire and watched that they were indeed firing out of order. What's funny is absent the backfire it seemed to idle better crossfiring. All cylinders are firing correctly now but the idle seems to be more irradic, and I cannot get the idle below 1100rpm. Maybe it's because it's out of the water and there's no back pressure. The "Backfire" is gone... and I cannot thank you guys enough for helping me, and hopefully someone else will learn from my mistakes. The only thing I can think that happened was the shop that worked on this thing prior to me, must have just thrown it back together and I just put it back together exactly as I found it. Of coarse wired wrong.
At this point I do not know why it will not idle below 1100 butterflies are completely closed and when I back off of the idle screw the idle just becomes more irradic and dies. Maybe one of you guys has an answer for that too.
Again... I cannot thank you guys enough for all of your input.
 
Thanks for getting back with the results of your troubleshooting.

With regard to your idle, which screw are you referring to?

The idle is controlled by advancing or retarding the timing, and the screw that does that is one that the timer base stops against when at the idle position.

If in doubt, it is best to consult an OMC service manual for the proper link and sync procedure.
 
I've had the somewhat the same issue. But mine runs great at every other rpm other than idle. After Carb rebuilds and new plugs,I found today that I was idled too low. And my timing was off. Just a thought. 85 horses should push it fine. I would also inspect primer bulb, fuel filter. Just to be sure.

Sometimes I find myself over thinking the problem. And it turns out to be something simple.
 
Sorry for bringing back to life an otherwise dead thread, but I just wanted to say THANK YOU to Goommer and especially Daselbee. I had a very similar issue as Goommer after doing some service on the engine. I couldve _sworn_ I had marked cyls #2 and #4 properly but I mustve somehow switched them. I have been pulling my hair out for days wondering WHY my engine is backfiring intermittently. I marked my fly wheel as racerone and daselbee mentioned and found that #2 and #4 were firing at the wrong time. Swapped them over and VOILA, all is working as it should!!! Thanks very VERY much!! :)
 
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