Humminbird problem !

[HemlockNailer]

Help, the boat has an older model Humminbird depth finder. When running, I experience static interference on the screen . The factory rep suggested adding a (Surevolt) unit, anybody ever used one or know anything about them?

[ESOX]

Do you mean it's erratic whenever the big motor is running? Or just the depthfinder itself is erratic? I have a hundred Ideas, and I don't think a surevolt is called for, at the WORST you might need a diode in the line (all of 2 bucks if you get ripped off ) But a little more specific information would be helpful.

[MGV]

All i can say is use the hummingbird as a anchor and buy a lowrance. I had problems with mine and worked on it for a year or so and then gave it away. I would of felt guilty if i sold it to someone. Anyways it sounds like your getting feed pack. Try checking your ground connection.

[adjusted]

I too had a similar problem when I installed my Eagle graph. What I found was that I had installed the wrong spark plugs in my outboard. Inspect the spark plugs and make sure you have resistor plugs installed. Does not matter the kind of graph you have, with out resistor plugs on older engines they will show static when running the engine.
The other item I found is to mount the unit away from any other electrical items that have magnets in them. Basically anything with speakers.

Good luck

[HemlockNailer]

Guys, thanks for your input on the subject. This will give me an idea of what to check as soon as I unwrap the boat. I will pos t when I get it nailed down incase anyone else is having a problem .