Quack Addict
Cadet
- Joined
- May 18, 2009
- Messages
- 25
My boat has a carbureted 350, Delco Voyager ignition, NGK BR6FS plugs.
The Humminbird 858c fishfinder is about a year old, barely used it last year and it has about 20 hours on it this season. I know I have an ignition interference problem at ~1000rpm (screen loads up with static) that I suspect is due to the transducer wire being run too close to the tach wire in the main wire bundle that goes to the helm. At 700RPM idle, even 800, or 900 RPM, the FF has been fine - it loads up with static at about 1000+RPM. I plan to address that in the near future but the boat is 200 miles away, wife is 5 weeks from her due date and I've been spending time getting the nursery in order...
Anyhow, a possible new gremlin surfaced this weekend and I'm not sure what to make of it. I added a device at the helm (speed / temp probe that I can switch completely off) but the new issue happens regardless. If anything, I'm guessing some wires got moved around where something isn't happy anymore. Maybe the transducer or signal processer is going bad - the depth reading started blinking out but the display still maintains bottom lock. Sometimes a weak signal as evidenced by the bottom return.
Here's what the display looks like...
Depth reading is ok (213') but the sonar return is really weak. Toward the left, you can see where the sonar return had been strong:
Depth reading blinked out, still weak bottom return:
A little later the return is more 'on' than 'off':
And then after things seemed like they were ok for a time, the return again becomes really weak:
All this was with the engine at the same 700rpm idle. Our trolling direction changed some (90*) but the water was almost glass calm with minimal current, and shouldn't have had any effect on signal return. The colored horizontal lines (and z line in the last pic) is downrigger cannonballs - you can see my probe rigger (1 line is probe, other is the cannonball) getting raised ~20' in the last pic.
Alternator seems to output a little low (13.8 volts) but no ill effects have ever been had with it doing this in 125h on the water. Occasionally it climbs to 14.x volts, might be engine speed dependent (haven't noticed a correlation). Not sure if this would play into the FF issue.
Any ideas?
My plan:
Step 1 - Break out the transducer wire and give it more physical separation from the main helm bundle from the transom to the helm.
Step 2 - Disconnect the Hbird's power & ground from the boat and connect to a stand-alone battery not connected to the boats charging system.
The Humminbird 858c fishfinder is about a year old, barely used it last year and it has about 20 hours on it this season. I know I have an ignition interference problem at ~1000rpm (screen loads up with static) that I suspect is due to the transducer wire being run too close to the tach wire in the main wire bundle that goes to the helm. At 700RPM idle, even 800, or 900 RPM, the FF has been fine - it loads up with static at about 1000+RPM. I plan to address that in the near future but the boat is 200 miles away, wife is 5 weeks from her due date and I've been spending time getting the nursery in order...
Anyhow, a possible new gremlin surfaced this weekend and I'm not sure what to make of it. I added a device at the helm (speed / temp probe that I can switch completely off) but the new issue happens regardless. If anything, I'm guessing some wires got moved around where something isn't happy anymore. Maybe the transducer or signal processer is going bad - the depth reading started blinking out but the display still maintains bottom lock. Sometimes a weak signal as evidenced by the bottom return.
Here's what the display looks like...
Depth reading is ok (213') but the sonar return is really weak. Toward the left, you can see where the sonar return had been strong:
Depth reading blinked out, still weak bottom return:
A little later the return is more 'on' than 'off':
And then after things seemed like they were ok for a time, the return again becomes really weak:
All this was with the engine at the same 700rpm idle. Our trolling direction changed some (90*) but the water was almost glass calm with minimal current, and shouldn't have had any effect on signal return. The colored horizontal lines (and z line in the last pic) is downrigger cannonballs - you can see my probe rigger (1 line is probe, other is the cannonball) getting raised ~20' in the last pic.
Alternator seems to output a little low (13.8 volts) but no ill effects have ever been had with it doing this in 125h on the water. Occasionally it climbs to 14.x volts, might be engine speed dependent (haven't noticed a correlation). Not sure if this would play into the FF issue.
Any ideas?
My plan:
Step 1 - Break out the transducer wire and give it more physical separation from the main helm bundle from the transom to the helm.
Step 2 - Disconnect the Hbird's power & ground from the boat and connect to a stand-alone battery not connected to the boats charging system.