Why wont it run? Please help

[fastisbetter]

Hello everybody! I finally got my hands on an engine for my '07 450. Clean, low hrs for what I would say was a reasonable price. Got it all mounted and hooked up, fired once for about 2 seconds, then died. Now, I need some sage advise. Valves in spec, looked in the throttle bore while cranking and the injector is spraying nicely. Pulled the plug and checked spark. Fat blue spark but it doesnt seem often enough and seems kinda sporadic. Checked another plug, same thing. Ohm'd the pulse coil at 97.9ohms, stator at 5ohms all three positions. I have another stator that is around 2ohms for all three. Ive searched this forum and google looking for values for these parts or similar problems but this is hard to describe in a search bar. If I hold WOT while cranking, I can get a backfire loud enough to flatten a small building, but that is it. I'm running off a car battery as the stock battery does not last long enough to do any testing. 12.65v drops to 11.7 volts while cranking. Sorry for the long post, just want to give out all the info I can so that maybe someone can help me. Its been a long two seasons without my baby and I'd love to get a ride in b4 the long Nova Scotia winter sets in.

[motopsycho87]

Sounds like ign timing or a dead coil. Sttar with spark plug and move back

[fastisbetter]

Tried the plug, same thing. Gonna pull the pick up coil tonite and swap it as I have a spare. I did have it running yesterday for 10 minutes. Ran like a top. Revved good, Idled great, but as soon as I shut it off and put it back together. No start again. Anybody know the resistance values of the coil and stator? Maybe the coil on the plug as well

[MercyFlush]

Originally Posted by fastisbetter

Tried the plug, same thing. Gonna pull the pick up coil tonite and swap it as I have a spare. I did have it running yesterday for 10 minutes. Ran like a top. Revved good, Idled great, but as soon as I shut it off and put it back together. No start again. Anybody know the resistance values of the coil and stator? Maybe the coil on the plug as well

How long ago did you put the fuel in? I ask because when I bought my bike unbeknownst to me the fuel was easy 6 months old. The bike VARY rarely ran (after I completely rebuilt the engine), and I tell you now, the LAST thing I thought to change was the bloody fuel. I was checking this that and the other, but nope, it was fuel. Also pull the fuel pump relay and give the contacts a clean and spray with CRC or WD40 etc.

[fastisbetter]

So I swapped the pulse coil and away it went. However, in my haste to get it back together, I hooked the battery up backwards. Man do I feel stupid. Popped the 30a fuse. Replaced the fuse but now Ive got no fuel pump or instruments. Cranks over but no go.

[MercyFlush]

Originally Posted by fastisbetter

So I swapped the pulse coil and away it went. However, in my haste to get it back together, I hooked the battery up backwards. Man do I feel stupid. Popped the 30a fuse. Replaced the fuse but now Ive got no fuel pump or instruments. Cranks over but no go.

Sounds like a short. Check everything you touched while changing the coil. If you have one of the trailtech style gauges then don't worry about that, they are bipolar and can accept power either way. Otherwise also give your relays a tap when the ignition is on. Also check your kill switch to see if it's getting/providing power, they usually cause all sorts of issue.

[fastisbetter]

got it sorted, it fried the pwr circuit in the ecu. good easy spot to repair tho. up and running like a champ. Thanks to everyone for the help.