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26 replies

Fuel gauge fuse blowing on me.

G Guest
Occasionally, my "Italian side" of gauges would conk out, usually a quick spin of the fuses fixed that.

Today, I noticed the gauges had died, so I spun the fuses, and found the last fuse, the one going to the fuel gauge was blown.

I replaced it, and it blew again within a couple seconds. I did notice the fuel gauge working properly for the few seconds before the next fuse blew (it wasn't pegged to one side or the other).

I noticed the fuse above the last one, the one for my windows was warm, but still functioning. I did not check to see if it was the correct fuse for the port, but my passenger window doesn't work (I think I need to install a new switch, which I have) and my drivers window does still work.

Windows have the Vader kit installed.

Just wondering where I should start looking to find why my gauge fuse is blowing.

My car has a second set of gauges that DO work, so the only gauge I'm really missing is my fuel gauge, but I'd rather have it all working fine.

I have a DMM, I'm obviously getting voltage to the fuse, amperage seems to be the issue.

I'm wondering if the windows and gauge fuse use something in common. I noticed the gauges died just after I had opened my drivers window.

I'm going to replace the passenger side window switch (which DID work once or twice at one point), go back and check everything on the whole fuse board is correct again, and go from there.

The fuel gauge fuse also powers the amp gauge, maybe I have a regulator going bad on my alternator?
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MT mike the snake (Guest)
Thanks for the links.

I'm back to where the car was when I bought it. One taillight works with lights-ON, no brake lights, no blinkers, no fuel gauge,
Pretty sure I have a dead short somewhere.

I'm going to start with my taillights and blinker lights, because I had the lenses off the other day, and wiped the insides of the reflectors, and may have knocked a light or something, not sure, I just know it's all dead now! It's All Dead!
panteradougpanteradougMember
+1 on the ground stud under the dash on the drivers side. It corrodes and causes a lot of havoc.

The other thing is the fuse panel itself at some point becomes undependable.

The wiring in the harness is of a very high marine grade and the metal itself is plated with anti-corrosion plating. Usually the wiring is not the curlpret.

On occasion the "quick connect" terminals will become loose and sometimes in close proximity will touch each other.

It really is time to change out most of the components like the fuse panel. They look very innocent until they suddenly dead short and this car was not equipped with an "entire car" fuse like the new ones are.
MT mike the snake (Guest)
Today,
i'm going to start with checking out my taillight bulbs and wiring.

The last thing I touched before all this started happening was cleaning the inner reflectors where I DID bump against the bulbs, so I'm hoping maaybe I just pushed a bulb over enough to short it out.

The "check the last thing you touched rule" applies here, then I'll go digging with my DMM.

I disconnect my battery after driving the car, it has a knob I turn to disengage the battery.

I'll hopefully find something amiss today.
MT mike the snake (Guest)
OK I'm trying to make sense of this.

Looking at the backside of the gauges, my amp gauge has a big hotty wire, with another big red wire going up to what I assume might be the ignition.

The red hotty wire comes from one of the aftermarket relays installed by the previous owner.

On the back of the amp gauge the rubber/plastic insulator caps show they've been melted (things have gotten REAL hot).

The amp gauge I'm not sure works or not. It moves a tiny bit, but never swings or changes when I open the windows.

It's obviously gotten REALLY hot, these are BIG wires, and the rubber/plastic insulator caps that go over the screw are melted away.

I THINK this is where my problem may lie.

Maybe my voltage regulator is over-amping? If so, wouldn't a relay pop?

I was told to cycle the inginition twice before starting to prime the fuel system, could this do anything funny?

The other things like my lights seem to be just corroded fuses. Corrosion is super accellerated, or maybe this is just Lucas?

Presently, the fuse lasts about 5-10 seconds then pops.

The amp gauge seems to still work (it moves minutely) but fuel and oil pressure gauges die with the fuse.

I'll study the diagrams posted earlier and see if i can make any sense of this.
huskerhuskerMember
If the fuse blew once it could be a bad fuse. If the second one also blows you have a short somewhere. The ammeters are notorious for failing. If the boots have melted it was probably due to a loose connection. Since it doesn't indicate discharging when you open the windows this could be an indication of a bad meter (assuming the wiring for the windows had not been altered from stock.
panteradougpanteradougMember
Your fuel gauge needed to be run off of an electrical relay? Really? Why? That makes no sense.

If the fuses in the panel are still in line with the gauges, what purpose does the relay have?

Sounds like some kind of an alchemist wired this thing. You might need to hire a witch doctor to fix it?

I had one but he got deported back to Haiti as an illegal alien? Sorry.
Last edited by panteradoug
jfb05177jfb05177Member
Is it fuse 12 that blows?
Is fuse 12 25Amp?
Does the fuse blow AFTER you turn key to run?


Do you have a multimeter?
with fuse 12 pulled, key at run,
on VDC, measure terminals and verify ~12VDC on one side and 0 VDC on the other
On Ohms, measure the fuse terminal that had 0 VDC to ground and verify the resistance is above 0 ohms, I don't know the gauge resistance, but if it is less say 10 ohms, that still would only be a couple amps

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MT mike the snake (Guest)
Roger Sharp is the one who made the relay panel. It is proven, and others here run it to this day.

The fuel and oil pressure gauges are Not running off the relays. Only the high-draw stuff, fans, lights, etc. are powered by the custom relay panel.

I spent the day removing, cleaning, lightly sanding every contact on every fuse and reciever tab. No grease, or metal protector this time. Corrosion happened REALLY fast with whatever I used before (Dielectric grease I think).

With the car OFF, I got everything back working. Most of the fuses were just corroded, so my taillights and brake lights I got back working.

The blinkers seem to be tied to the gauge fuse (#11) which on the sticker on the panel says is supposed to be for the windows right and left, so maybe some stuff has been changed around a bit.

It is fuse #11 that blows, and when it blows I lose blinkers, fuel gauge and oil pressure gauge I'm pretty sure.

The amp gauge moves ever so slightly, and continues to "work" even with the blown fuse.

Til now it's all been working fine. I did have the same items die before on me but I just spun the fuse and it all worked again, so I chalked that up to corrosion.

This is the first time it's actually blown the fuse like there's something wrong.





quote:
Originally posted by PanteraDoug:
Your fuel gauge needed to be run off of an electrically relay? Really? Why? That makes no sense.

If the fuses in the panel are still in line with the gauges, what purpose does the relay have?

Sounds like some kind of an alchemist wired this thing. You might need to hire a witch doctor to fix it?

I had one but he got deported back to Haiti as an illegal alien? Sorry.
MT mike the snake (Guest)
On my car, fuse #11 seems to cover the things that fuse #12 does in the diagram you posted here.



quote:
Originally posted by JFB #05177:
Is it fuse 12 that blows?
Is fuse 12 25Amp?
Does the fuse blow AFTER you turn key to run?


Do you have a multimeter?
with fuse 12 pulled, key at run,
on VDC, measure terminals and verify ~12VDC on one side and 0 VDC on the other
On Ohms, measure the fuse terminal that had 0 VDC to ground and verify the resistance is above 0 ohms, I don't know the gauge resistance, but if it is less say 10 ohms, that still would only be a couple amps
MT mike the snake (Guest)
here's a pic of the sticker next to the fuse panel.

It seems the functions of 11 and 12 have been switched on my car.


Also still not sure why my amp gauge shows the signs of getting so hot at the contacts.

My guess is the previous owner moved around some things just to make stuff work.

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MT mike the snake (Guest)
Well, you got me there. I was wrong.

The red wire I found to be an addition that powered a long-gone CB radio, and it looked like it went to the gauge when I looked under there.

Wiring is not my forte, please excuse me.



quote:
Originally posted by PanteraDoug:
Put it this way, the fuel gauge hardly draws enough current to blow a fuse...and YOU were the one saying that there was a red wire running from the gauge to one of the relays.

As far as installing relays goes...the contacts corrode. Want the link with the pictures?
panteradougpanteradougMember
I'm not trying to trip you up, just trying to understand what is going on.

The original alternators have a reputation for catching fire. All the power in the car runs through the original design.

Look at the gauge and try to determine if it is the original or has been changed.

I changed the Veglias out to VDO a long time ago. I do know that Hall sells a "safe" replacement Veglia ammeter.
MT mike the snake (Guest)
I haven't fired the car up yet. I did arm the ignition and check that I had everything back working, including the gauges.

It seems, IF the fuse blows within a few seconds, as it has so far, that the fuse is blowing with the the car running.

Maybe voltage regulator overamping?
MT mike the snake (Guest)
One thing I DO do is disconnect the battery after every drive (I have a knob on the battery terminal that I turn that disables the battery).

I know most regulators run batteries around 13-14 volts.

Could my disconnecting the battery directly after use be keeping the voltage high on the battery?

I can't see how it could, IMO most batteries lose that extra charge in an evening anyways, but I was wondering if leaving it hooked up might level the voltage out on the battery?

I've had other cars that slowloy killed batteries off if left to sit for too long, so I just unscrew the knob after driving, tighten it when I go to drive.
goodrocgoodrocMember
It is very easy to determine if a regulator is working. With engine running the voltage measured on the battery must be 13.5-13.8 volts (or close to that) if it is more than 14volts or less than 13volts your regulator has failed. The regulator is not your problem from what I gather. I would take that previously overheating amp gauge and throw it as far as I could, it is a ticking time bomb (besides it provides absolutely useless and unreliable information even when it was new) Install a volt gauge in its place. Tie the 2 fat wires on the amp gauge together and use them as the + to feed the volt gauge and make sure they have a really good connection. A volt gauge will provide you with all the information you need to know about your electrical system (in respect of the charging status)
rockyrockyMember
quote:
Maybe voltage regulator overamping?



There is no such thing as "overamping", unless you have a short.

The Alternator can generate a higher VOLTAGE, but to burn stuff up, the circuit has to have a low-resistance path to ground.

As Joe stated, an increase in voltage might boost your current by 10-15%.

But this (relatively) small increase in current caused by the higher voltage will not be the difference between a fuse that doesn't blow, and one that blows in 5 seconds.

Electicity is like plumbing, were voltage is PRESSURE, and current is FLOW. Electricity always goes from the high pressure (voltage) side, down to ground (at least for the purposes of this discussion).

You need you get your multimeter out, and figure out how that FLOW on circuit XX (??) is getting to the drain (ground), by finding the wire or connection that has a very low, or no, resistance.

You have to figure it out by "boots on the ground", since there are a lot of wires, it is hard to help over the internet. Understanding how the electrical system really works will help you in your quest.

Good Luck - Seriously.

Rocky
Last edited by rocky
jfb05177jfb05177Member
Just looking at the schematics, I was a little concern that the fuel sender went to 0 ohms at "full". ie 0 ohms being a short circuit and thus a LOT of current. SO I went and checked my gauges and determined they appear to have internal current limiting resistance. the fuel and water gauges were 130 ohms and the oil gauge 82 ohms.

assuming the worst case of all three gauge senders were 0 ohms (grounded) the effective resistance of the three gauges would be 37 ohms; thus only about 2 1/2 amps

the original wiring for fuse 12 should have the brake lamps, backup lamps and a radiator fan motor besides the gauges. if these devices are OFF, then the fuse resistance should be greater than 37 ohms (working senders will increase resistance. light bulb's resistance are very low when not hot
MT mike the snake (Guest)
Finally found the issue!

I had recently cleaned the taillight lenses, and popped the bulbs out to check for corrosion.

The rubber/plastic shielding on the wire going to the brake light had moved over enough to short against the bulb housing, causing a dead short.

After messing and checking the right taillight and wiring, I went to the left one and found the culprit. Shrunk wire shielding.

I used that liquid black tape stuff, and also put a piece of silicon model airplane fuel line around the bad area, so it's impossible for this to happen again,,,,at THIS spot.

The wiring on the car is ancient. As the car is not restored, I'm going to just run end enjoy, and fix as necessary, any more wiring issues (knocking on wood).
MT mike the snake (Guest)
Apparently, yes. The two do go hand in hand with me while driving.

I'd caused the short by messing (cleaning) the lenses and reflectors) but didn't notice the fuse pop til I hit the brakes. Also, it took a few seconds for the fuse to blow, momentary brake taps didn't pop it.

Also, it seems some fuse locations were switched around by the previous owner, which made things extra difficult, had me looking in the wrong places.
MT mike the snake (Guest)
Thought I had the issues licked, but with the headlights on, when I hit the brakes my right brakelight and taillight go dead.

Otherwise, all works OK, although the right side brake light glows dimmer than the drivers side.

Now the throttle is sticking, I think the pedal/cable is hanging up on the console side cover (which I had off while troubleshooting the electrical issues.

Now, a throttle blip lasts a full second, and is scary. Normal easy driving all works OK, but the throttle should be issue-free IMO, so now there's one more thing to deal with.

This car is getting the best of me.

I'm tempted to throw a cover over it and forget I bought it for 6 months, come back at it with a better attitude.

Presently, it's one thing after another, and I'm having trouble keeping up.

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