depth finder problem

Hey guys ,I got one for ya. Im using a Hummingbird 200DX depthfinder located on the console of my boat. Using a shoot through the hull transducer. This setup has worked fine for 2 yrs, it worked fine the last time I used my boat last fall. Now all the sudden when my engine is running my depthfinder cant locate the bottom. This happens even when Im in neutral. Ive checked all my connections, No corosion, no loose connections. If im fishing just using my trolling motor it works perfect. I aint gotta clue. Any ideas???

have you changed spark plugs?it's interference you just need to find what started causing it,have you rewired or re routed anything?

You might need to check your transducer cable. I had a simular problem with a eagle and my battery had moved over and wore into the cable. It worked fine for awhile unless the motor was causing it to viberate. Just a thought.