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What the Hell is That?
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Discussion Starter #1
OK its a 72 Hondo, 327 Chevy. Mallory Coil and cap.

I was putting on my Gauge bezels, and accidentally shorted a hot wire on a Gauge brace.

Fixed that problem, and when i was running the Fuel pump to set the pressure One wire under the dash started to burn, I thought it was just the wire because it was old. Replaced the wire and I noticed all the wires get really really hot under there. Took the meter to them and found Every wire was getting voltage with the ignition off. Maybe the first short shorted something else?

I have spent over 5 hours look for this short I now for a fact its not in the gauges. I totaly removed the harness I have gone thru most of the wiring to see if there was one exposed touching a ground but i haven't found it yet. As of right now 3 Wires are showing 3 different volts, Ignition, Water temp, and a red one i haven't found where it goes yet.

Anyone have any ideas? I'm stummped ! Nothing is black anywhere so nothing shorted that bad.

Sorry for the long post but for 6 hours work and to be in the same place is frustrating
 

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Just Me
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Check the ignition switch. It is possible it shorted internally. It is also possible that the ground burned up and that things are grounding through the guage circuits. Since it isn't full battery voltage, I'd suspect a ground that isn't grounding now. What guage shorted?
 

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What the Hell is That?
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Discussion Starter #4
The boat is located in the SFV

Its not the igintion swith, at the moment its not in the circut, the harness is totaly out just a bunch of wires running to teh back of the boat.

The orginial gauge to short out awas the Ampres Gauge with an "Always hot" wire
 

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Just Me
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check where all your grounds go. I would guess it to be the ground from the instrument cluster burned internally. The voltage is now grounding back through the instruments or the light grounds. just disconncet the battery and start checking for a burned ground wire (using the ohm meter). Also try unhooking the altenator if you have one. It could have burned out the diode trio in the altenator.
 

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Get rid of the amp meter and get a volt meter instead! Those things are a fire hazard as you almost found out...
 

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What the Hell is That?
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Discussion Starter #7
Will will check and go through all the grounds tomorrow.

I did disconnect the ALT and check the Diode. Diode is fine and the wires still see voltage with the Alt disconnected.
 

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What the Hell is That?
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Discussion Starter #8
I just thought of something while I was at work.

Did anything change with the Holley "Blue" fuel pumps?

Now that I am thinking about it, the way the boat was wired is Everything piggy backs of one gauge post. which is also the post the Fuel Pump is wired too. When i turn the ignition on to ACC for the fuel pump thats when everything gets hot and I smell burning.

Could the pump be drawing so much current that its taking away from the other gauges? Holley says its a 3 amp draw.

I recently replaced the fuel pump with a brand new Holley "Blue" From an Old worn out Holley.

Could this be it? Sorry if I'm just throwing shit out there.
 

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Just Me
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If the holley pump was drawing too much it would be the wire leading to the post hot, not the guage wires. Where does the holley pump ground? Did you use the same wires as the old Holley? 3 amps grounding through small guage wires will cause them to get really hot. IF the pump isn't grounded or if you grounded it to your guage buss and that ground is bad. It could explain the back feed through the guage wires. I still think your problem is ground related.
 

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you didn't by chance put the battery leads on backwards? did anything change or get messed with at the back of the key switch? also the only other heads up that comes to mind that could do some crazy stuff is that amp meters wire in series and volt meters wire in parallel. in other words if you wired your amp meter like a typical gauge your almost at a dead short. in other words there should be no"ground wire" at the amp gauge unless it is for a light inside the gauge for night time cruising. hot wire from alt. to guage and hot from guage to +bat.
 

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What the Hell is That?
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Discussion Starter #11
No ground on the Amp meter.

Battery not wired backwards or else wouldn't be getting any voltage anywhere.

The Ignition switch was changed out but replaced with the same type .
 

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have yuh checked stuff with a meter?maybe turn the key to off and check the back of the switch?just wanted to help but hard to do blind -Jas
 

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What the Hell is That?
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Discussion Starter #13
I know! :D

I have two Meters One digital and one Analog. tomorrow i am going to hook up everything back up minus the Fuel pump wire and see if wires get hot...

could just be that I'm tired but when i think about it i always touched a wire leading to that post where everything is piggy backed on including the fuel pump and i want to say its ony + wires that go hot.

But whats to explain the voltage on other wires with the ignition off? :|err

Why couldn't the Original owner wire this simpler and do a diagram for it! :)sphss
 

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I know! :D


But whats to explain the voltage on other wires with the ignition off? :|err

sphss
thats what made me think the poles were reversed. not sure that the battery wouldn't just blow up if so,lol. but you would definantly get a voltage whether or not the key was on.when i get to a real sob in the field i will draw out the schematic by hand putting down onl;y what i have visually varified or varify with meter 100%positive. thing have away of washing out that way. it can be time consuming but bette than guessing...and maybe cheaper and faster.who knows.
 

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What the Hell is That?
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Discussion Starter #15
Well we will see what happens today. I have a friend coming over who has a Tone Tracer and I am going to go threw everything once more.
 

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Sit N' Spin
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1,423 Posts
The fuel pump should be on a circuit all its own controlled with a relay. The relay contacts should be wired between the battery and the fuel pump hot, while the relay coil should be wired between ground and the "Hot In Run" terminal on the terminal block on the back of the engine. Locate the relay as close to the fuel pump as you can so that the runs between the fuel pump and the battery are as short as possible. Also you should use at least 12 gauge wire between the pump and the battery. With this setup the fuel pump pulls straight off the battery instead of trying to draw 3 amps of current all the way from the battery to the dash and back.

Hope this helps.
 

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What the Hell is That?
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Discussion Starter #17 (Edited)
OK so i did some digging today...

Here is what I found, the problem lies in the fuel pump. With out the fuel pump in the circuit everything goes fine water/amp/Tach/bilge everything runs fine wires do not get hot at all.

hooked up Fuel pump, all goes to hell wires start to smoke and they get very hot, Grounds/Senders/pwr wires. they all get damn hot.
 

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painless brand fuel pump relay. comes with instructions/diagram.
http://www.jegs.com/i/Painless/764/30131/10002/-1
it's a simple thing to make a mounting bracket for this deal.
sounds like there is a short inside the fuel pump? is there still voltage with the key off when the fuel pump is hooked up?does the pump only heat everything up under load?
 

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Sit N' Spin
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1,423 Posts
painless brand fuel pump relay. comes with instructions/diagram.
http://www.jegs.com/i/Painless/764/30131/10002/-1
it's a simple thing to make a mounting bracket for this deal.
sounds like there is a short inside the fuel pump? is there still voltage with the key off when the fuel pump is hooked up?does the pump only heat everything up under load?
I'm thinking its because the fuel pump draws way too much to be hooked to the gauge circuit wiring, which is why I suggested the relay to run it off its own circuit isolated from everything else.
 

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Just Me
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4,059 Posts
Now that you've isolated the problem, have you considered getting rid of the initial cause? Replace the amp guage with a volt guage. Amp guages only tell you the story if all the electrical runs through it. If you are going to give the battery a seperate curcuit, which I agree with) the amp guage will not tell you the real story anymore. A volt guage can tell you just as much about your charging system and you will know where you stand if you loose your altenator and have to limp back home on battery. As long as you're fixing things. :)hand
 
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