engine works and radio works but not together

[jfw432]

I just installed a radio in my boat. I tested the radio and everything appears to be working properly. I then went to crank the boat up to figure out how it sounded at speed and the boat wouldn't start. It would turn over but would never fire. The coil was warm so I assume it was getting juice which should mean that the spark plugs were getting juice but I can't confirm that for sure.

Anyway, after some thought, I unplugged the power cables from the back of the stereo and the boat fired up instantly. Plugged the stereo back in and it wouldn't start. I currently have the radio wired as follows: The memory backup wire (yellow) is connected to the constant 12v source going to the ignition switch. The ignition wire (red) is connected to the other side of the ignition switch that powers all the gauges when the key is in the on position. Finally, the ground wire (black) is connected to the ground wires for the gauges. The gauges operate properly when I'm cranking. I'm not running an antenna.

Do you guys see a problem here? How is this preventing the boat from starting? The boats power and ground wires are 12-14 gauge and the wire to the radio is probably 16-20 gauge so it can't be sucking that much power...especially when it's off.

 

[Lyle29464]

Re: engine works and radio works but not together

If you have a outboard It sound like you have hooked a radio wire to the kill side of your switch. I would recheck that wire.

 

[fish_on_the_deck]

Re: engine works and radio works but not together

The memory backup wire (yellow) is connected to the constant 12v source going to the ignition switch.

At first I was going to say "coincidence" but wanted to comment on the memory wire going to your ignition... when the battery switch is of, your still going to loose your memory... you need to go all the way back to the battery + before the switch.

After reading lyle's post, maybe you have somehow bypassed the kill switch which is normally open with the red and yellow wires, simulating the kill switch being off only when the stereo switch is ON... haha (not laughing at your problem)... that is quite an interesting scenario if true. I just have to chuckle a little at the odds of those two separate systems working against you in this harmless but terribly frustrating way...

I suggest disconnecting the memory wire and temporarily attaching it with the ACC wire. See if that solves the problem.

-good luck

 

[jfw432]

Re: engine works and radio works but not together

This boat doesn't actually have a kill switch and it's a full inboard boat with a Ford 351 windsor engine. The wire that I hooked my memory wire to is always hot and because it's always hot, it's fused to prevent damage to the ignition switch but the fuse hasn't blown. I did try swapping wires around a bit with no success but I may have just been swapping them to the same set of wires just further down the line.

Tomorrow when it's light, I'll try hooking both of the radio wires directly to the battery and if that works, I'll try hooking just the memory to the battery and then the ignition wire to the switch. If both positives running to the battery doesn't solve it, it has to be the ground that I tied into. Hopefully that will solve it. It still doesn't make any sense that tapping into a 12v wire designed to run the accessories in the boat and using the central ground for those accessories won't run another accessory.

Of course, I recently changed the gas filler cap in this boat and that killed all of the accessories. Still not sure how disconnecting a wire that runs to a fuel filler cap and connected to fiberglass and a rubber hose could ground anything but it did until I replaced the cap and had to run a dedicated ground. So this boat does have some funky wiring going on.

 

[Lyle29464]

Re: engine works and radio works but not together

The gas filler ground is doing the work of the regular ground. you need to fix that fast. You should have a ground from the battery to the buss under the dash. That must be unhooked. You did,t tell us what you were working on so I made a jump to the only thing that fits. Now I need to rethink a bad ground thingee.

 

[jfw432]

Re: engine works and radio works but not together

The gas filler ground is doing the work of the regular ground. you need to fix that fast. You should have a ground from the battery to the buss under the dash.

Don't worry I fixed that with the gas filler cap installation. The ground for all the accessories (to the best of my knowledge) runs to the aluminum gas tank in the back. I assume it's for the fuel level sender. When I fixed the filler cap ground, I ran a wire directly from the gas tank to the battery and that fixed all the problems until I installed the radio.

Come to think of it... I remember thinking that my fuel gauge shouldn't be reading "full" when I was trying to crank the engine because it's closer to half but I just blew that issue off because the non-starting engine was my main concern. I'm beginning to think that the ground is the source of the problem.

 

[bruceb58]

Re: engine works and radio works but not together

I'm beginning to think that the ground is the source of the problem.

Yes...me too. You need to run a nice big ground all the way up to your console from either you battery or engine block..

 

[Skiwi]

Re: engine works and radio works but not together

Am I the only one that would be a tad nervous using my gas tank/cap as a ground?
I personally prefer any potential for sparks to be further away from ignition sources.

I'm with the others, check your ground and run a dedicated earth from the battery to the buss.

 

[jhebert]

Re: engine works and radio works but not together

If use is continued of the safety ground conductor to the fuel tank as a current carrying conductor for the boat electrical distribution, this problem will resolve itself soon.

 

[sasto]

Re: engine works and radio works but not together

I would assume the fuel fill is bonded to prevent static electricity being present....could save you while filling up.

 

[jfw432]

Re: engine works and radio works but not together

Tried grounding the gauges first and got nothing but I ran a dedicated ground for the radio and everything works properly. The only thing I can think of is maybe the ground for the tach that I was tapping into works differently than I expected and it was shorting out the ignition while cranking.

The new gas filler cap that I bought doesn't have a grounding point on it like the old one. Should I drill and tap one?

 

[Lyle29464]

Re: engine works and radio works but not together

I think grounding the cap is a bit of overkill. No pun.

That wire is to keep the cap out of the ocean.

The fuel flowing through the nozzle builds up a static charge if the fill spout is not grounded. You should hold the nozzle so it rests on the deck fitting and the static is shunted to ground.

 

[bruceb58]

Re: engine works and radio works but not together

I have a feeling he meant the fill housing.

 

[jfw432]

Re: engine works and radio works but not together

Yeah I meant the fuel filler housing and not actually the cap. All the gas that goes into this boat goes in through 5 gallon cans.