Crusader 2004 Engine Ground Issue

[5050Luce]

So I have a Crusader inboard 2004 rebuilt before I bought it, has 15 hrs on it, on my custom 24ft wooden picnic boat that has a ground issue according to my outboard mechanic and many others I've spoken to. Every time the boat hits a wave or I turn quickly the ignition shuts off/engine sputters and backfires. Otherwise on a calm flat day it runs perfect.

I have been told to check all the grounds on the engine as they have replaced all the electronic issues it could be and they have ensured it's getting fuel.

Im wondering where to I start this wonderful journey. I have an ohm meter and can check lost ground, but am trying to get some help on where should I start with ground and if anyone else has experienced this issue.

 

[stresspoint]

start by ripping all the harness out and testing continuity ,
before you question ripping /taking the wiring out , with it on the bench it is easier to bend and pull individual wires to test for breaks in continuity, you can also inspect plug connector pins ,you can also see places out of sight to look for chafing.
it also makes cleaning grounds and replacing damaged wires more efficient.

engine harness removal is an easy job as it is mostly plug and play with a few screws and nuts.

if no smoking gun with the engine harness it time to start with the control harness , same again take it out and bench test .

locating intermittent bad connections is a PIA so be vigilant of even the smallest thing that looks out of place or damaged.

 

[Scott Danforth]

Start at the battery and clean every connection all the way to the helm and back (by clean, use 300 grit sand paper and make it shiny enough your mother in law would eat off them). then tighten and seal with marine electrical varnish

 

[nola mike]

Wiggle test. Just like it sounds. See if you can grab the wires, wiggle them and see if you can get the engine to die