Mercury XR2 SportJet Backfires But Won't Start

o0LiquidDark0o

Recruit
Joined
May 31, 2014
Messages
4
Hey guys. I have a 2000 Sugar Sand Heat with a Mercury 120 XR2 SportJet engine in it. It's popping, backfiring, and occasionally spitting flames, but won't start. Here's the background story . . .

I tried getting the boat running a few days ago and found that it wouldn't start. This is somewhat normal because the previous owner left dirty gas in the boat and the carbs keep getting gummed up (despited being cleaned and rebuilt several times). So it's not rare for me to sit and crank the boat over for a minute before it finally starts. So, I cranked it over a lot before finally giving up. I dove into the issue further and found that I had no spark (whereas I assumed it was a fuel issue). The ignition problem is now fixed and I have spark again.

I've turned the boat over for probably a combined 5 minutes and am getting lots of popping and backfiring, but it just won't run. I've checked to make sure that I have spark on every cylinder and that each spark plug is working. After cranking and I pull the spark plugs out, they all come out slightly wet, so I believe I have fuel.

Two weird things: When I'm cranking and the boat backfires, sometimes it stops cranking for 1-2 seconds, and then starts cranking again. Also, when I crank it over for a bit and then pull the plugs, quite a bit of smoke comes out of the top cylinder.

In my mind, here are the possible issues . . .
  1. The engine is still flooded from when I was turning it over with no spark. Keep on cranking it and eventually she'll go.
  2. When I was having the ignition issues, I did pull the flywheel. I marked it's position and am 98% sure that I re-installed it correctly. But maybe somehow I didn't and now the timing is off. I have no clue how to check this.
  3. I'm installing the spark plug wires in the wrong order. But I'm 98% sure they just go top to bottom as you'd expect.
Any thoughts or advice you guys might have would be extremely helpful. Thank you!
 

procraftguy

Petty Officer 2nd Class
Joined
Jul 7, 2013
Messages
137
Sounds like plugs are in wrong order or the flywheel ue on the right track id confirm topdead center at mark on fly wheel and check the plug order per manual had a force i sewiched and same thing happened
 

o0LiquidDark0o

Recruit
Joined
May 31, 2014
Messages
4
It turned out to be the flywheel. When I removed it, I didn't realize there was a "key" in the crankshaft and a groove in the flywheel that needed to match up. I figured I could just mark the position and reinstall in the same way. In any event, I corrected the flywheel and she fired right up.

Thanks for your help!
 
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