Engine Backfire

[Magnum Mike]

check the two white wires from the MSD enhancer.
One is short and one is long.
The short white goes to start/stop white, the long goes to stator white w/ red trace (female to female jumper needed on some models)

http://x-h2o.com/index.php?threads/msd-wiring-diagram.149041/#post-1614322

http://www.x-h2o.com/index.php?threads/ebox-wiring-diagram.73129/#post-925550

 

[Noodes7792]

If I look at the posted pic I think the long white is going to the white/red wire. I have zero's diagram from msd in hand when wiring

 

[Harbor]

When those white wires are reversed the symptoms are engine fires off momentarily, 1 second ish when the start button is released. Kinda backfires too at least mine did

 

[Noodes7792]

I will definitely take a look at it. Thanks for all the great info.

 

[Noodes7792]

White wires are wired correctly. It's an older Cdi so the jumper is not needed I don't think. White/red is a female going to stator. Replaced with stock Cdi. Now the issues is I push the start button nothing happens. Notice fuse was blown. Replaced it. Still nothing. Bilge works. No ignition.

 

[Noodes7792]

Just put the msd back in and boom fired right up. Wtf

 

[VXSXH20]

check, check and recheck the ground bolt in the ebox. also you can run (add) another small ground wire out the box ( using the same bolt as the others ) but bring it out the ebox grommet and find another ground on the engine block. clean the start/stop switch connector pins and use some Di-electric grease on the terminal pins and put back together I have had this happen to me before..

 

[mxr181]

My MSD enhancer recently went bad and was causing intermittent spark and the starting / backfire issues you were having. Hopefully that is not what your problem, but I would definetly pull the plugs, put them back in the boots and ground the plug to the head to make sure you have good, strong, consistent spark. Mine would spark when you first hit the button, then no spark, then spark again when you released the start button...swapped every part in the ebox with no change, then put stock cdi back in and bam, good to go. Hoping MSD will help out with a new one.