Help with wiring boyd rear fuel cell!?

[K10Dream69]

I cannot seem to figure out how to wire the fuel leveler inside of the fuel cell. Ever since I got the truck fired up, the gas gauge went all the way up past full.

I looked into it, and I just added a new ground from the battery to the frame thinking that was the problem and it wasn't. I've tried multiple locations for the ground with no luck. even with running an external jump wire just to test it the leveler still wont read.

so I broke out the wire tester and the factory location for the gas tank wire barely lights up on the indicator as saying a weak source. so I tap out of the ignition after starting it up to make sure I had a constant and it's still won't read.

I've tried everything I could and it's very frustrating. How did you set yours up? What did you do with the factory wire? Where did you ground it?

Am I missing something here or is this just a simple stupid fix?? Thanks
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[SS Tim]

Is the sender the correct ohm value for you stock gauge? The factory fuel gauge system is really simple. B+ to the gauge on one side and the sender sense wire on the other. The sender has the sense wire and a local ground. Did you ground it to the chassis or just the tank? Did you extend the original sense wire back to your new sender or did you just tap into it. Are you using a factory service manual schematic or something simplified?
Vette Vet is really good with these and here is a thread he posted to that should be very helpful.
http://67-72chevytrucks.com/vboard/s...d.php?t=327643

[jondancer]

I was also hoping the Boyd tank would come with directions .
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[buckskins4ever]

Originally Posted by K10Dream69

I cannot seem to figure out how to wire the fuel leveler inside of the fuel cell. Ever since I got the truck fired up, the gas gauge went all the way up past full.

I looked into it, and I just added a new ground from the battery to the frame thinking that was the problem and it wasn't. I've tried multiple locations for the ground with no luck. even with running an external jump wire just to test it the leveler still wont read.

so I broke out the wire tester and the factory location for the gas tank wire barely lights up on the indicator as saying a weak source. so I tap out of the ignition after starting it up to make sure I had a constant and it's still won't read.

I've tried everything I could and it's very frustrating. How did you set yours up? What did you do with the factory wire? Where did you ground it?

Am I missing something here or is this just a simple stupid fix?? Thanks
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Make sure to ground tank sender to frame. Everything under the dash will stay the same for you as if the tank was still behind the seat. For example you took the existing sender wire from the cab tank and ran it back to the new Boyd tank sender...???? I you did this you should only have to make a good ground to the frame from the tank and it will work perfect with existing dash gauge.

[jondancer]

is your sender marked + & - ?

[K10Dream69]

thank you for all the responses, after troubleshooting it today I finally got the wiring correct.

upon doing more research, I saw other members say a lot of times the float on the leveler gets stuck, and if your gas gauge goes way past full chances are that's the problem. So I took out the leveler out of the fuel cell inspected the float and put it back in, fired the truck up still with the same issue. it is not labeled positive negative, but from what I saw on other posts was the big one in the center is positive, and the small one on the side is negative. When I took it out of the fuel cell neither of them were labeled. But the negative had no connection underneath so it had to be the ground

So I finally have the connection right, why will my factory fuel gauge still not work?

Any other ideas?
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[VetteVet]

Originally Posted by K10Dream69

thank you for all the responses, after troubleshooting it today I finally got the wiring correct.

upon doing more research, I saw other members say a lot of times the float on the leveler gets stuck, and if your gas gauge goes way past full chances are that's the problem. So I took out the leveler out of the fuel cell inspected the float and put it back in, fired the truck up still with the same issue. it is not labeled positive negative, but from what I saw on other posts was the big one in the center is positive, and the small one on the side is negative. When I took it out of the fuel cell neither of them were labeled. But the negative had no connection underneath so it had to be the ground

So I finally have the connection right, why will my factory fuel gauge still not work?

Any other ideas?
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The biggest cause for the fuel gauge going past full is that the tank sender wire is disconnected from the circuit. Or the sender is not grounded to the frame.
Look on your fuse panel on the right or left end about center and you should see a terminal marked "FUEL", Is there a tan wire connected there? If not that is where the center terminal from the tank sender is supposed to go. If the wire is there then Pull it off and run a temporary wire from there to a good ground and turn the key on and watch the fuel gauge. It should go to empty or below. This checks the wiring from the fuse panel to the gauge.


Plug the tan wire back onto the terminal and check it for a broken spot back to the sender. Then check the sender for a good ground to the tank and the tank for a good ground to the frame.

All the wiring from the fuse panel fuel terminal back to the sender and to the frame is on the negative side of the circuit. Do not apply any positive voltage to this circuit. It could result in an explosion inside the fuel tank
Post back with the results. VV

[K10Dream69]

Originally Posted by VetteVet

The biggest cause for the fuel gauge going past full is that the tank sender wire is disconnected from the circuit. Or the sender is not grounded to the frame.
Look on your fuse panel on the right or left end about center and you should see a terminal marked "FUEL", Is there a tan wire connected there? If not that is where the center terminal from the tank sender is supposed to go. If the wire is there then Pull it off and run a temporary wire from there to a good ground and turn the key on and watch the fuel gauge. It should go to empty or below. This checks the wiring from the fuse panel to the gauge.


Plug the tan wire back onto the terminal and check it for a broken spot back to the sender. Then check the sender for a good ground to the tank and the tank for a good ground to the frame.

All the wiring from the fuse panel fuel terminal back to the sender and to the frame is on the negative side of the circuit. Do not apply any positive voltage to this circuit. It could result in an explosion inside the fuel tank
Post back with the results. VV

In the fuse panel where the factory tank was hooked up to "Fuel" is putting out little to no power, barely lights up the test light when ignition is turned on. So I took the fuse panel off last night and tested to wire directly with the same results, so the feed to my "Fuel" terminal is no good.
I switched it to an open (not used) one on the bottom of the fuse panel that only gets power off the ignition. Is this not ok?

I'm going to play around with it later tonight or tomorrow.

Thanks

[VetteVet]

Originally Posted by K10Dream69

In the fuse panel where the factory tank was hooked up to "Fuel" is putting out little to no power, barely lights up the test light when ignition is turned on. So I took the fuse panel off last night and tested to wire directly with the same results, so the feed to my "Fuel" terminal is no good.
I switched it to an open (not used) one on the bottom of the fuse panel that only gets power off the ignition. Is this not ok?

Hell No, what part of explosion do you not understand.

I'm going to play around with it later tonight or tomorrow.

Thanks

......like I said, this side of the circuit is the ground side of the fuel gauge . You go putting power on it and the resistor on the sending unit will heat up and might ignite the fumes in the tank.
The reason you're not reading any voltage on the fuel terminal in the fuse panel is because the resistor on the back of the fuel gauge drop the voltage low enough to protect the gauge and the sending unit resistor.

[SS Tim]

VetteVet, You have patience, but then most people don't realize a test light does not begin "tell all" even on these simple truck systems.
Funny thing is this reminds me about a mechanic who could not diagnose a power window problem on a customer's old Mercedes sedan. Everywhere he tried his tester into the "wires" there was no power. Three days later someone pointed out they were vacuum operated windows. He ended up replacing a lot of vacuum hose.

[VetteVet]

Originally Posted by SS Tim

VetteVet, You have patience, but then most people don't realize a test light does not begin "tell all" even on these simple truck systems.
Funny thing is this reminds me about a mechanic who could not diagnose a power window problem on a customer's old Mercedes sedan. Everywhere he tried his tester into the "wires" there was no power. Three days later someone pointed out they were vacuum operated windows. He ended up replacing a lot of vacuum hose.

right you are Tim but I had to come back strong on K10 Dream cause I sure wouldn't want to see him get hurt. I meant no offense. VV

I got you on my friends list.

[K10Dream69]

[QUOTE=VetteVet;6044878]The biggest cause for the fuel gauge going past full is that the tank sender wire is disconnected from the circuit. Or the sender is not grounded to the frame.
Look on your fuse panel on the right or left end about center and you should see a terminal marked "FUEL", Is there a tan wire connected there? If not that is where the center terminal from the tank sender is supposed to go. If the wire is there then Pull it off and run a temporary wire from there to a good ground and turn the key on and watch the fuel gauge. It should go to empty or below. This checks the wiring from the fuse panel to the gauge.


So I removed the tan wire from the other ignition terminal I had mentioned previously, No explosions haha.

I did the test you mentioned about a temporary wire and the gas gauge wen't down to empty like you said. Soon as I put it back it went way past full and that's where it's staying again.

I've check the wire and it is fine without any kinks or anything, I have the leveler grounded to the small crossbrace that has to be moved forward to fit these tanks, do you think this ground is not sufficient?

I appreciate the help and I know it's only two wires yet something so small and dumb is holding up my entire project. Once the gauge works I can put the bed back on

[jorgensensc]

Again, is your sender using the correct ohms value? O-90, if not then it would read full when empty. Take the sender out, leave the ground and wire to the fuse block on it, then move the float level arm up and down, SLOWLY! Do you see any movement on the gauge. If you want you can take the sender up by the fuse block. Run a wire from the + terminal on the sender to the spot on the block marked fuel. Then run a wire from the negative to the a (good) ground somewhere. Then see if the gauge moves at all. Take a picture of your wiring for us if you can.

You may have blown the resistor when you gave the sender full power. So you may have to buy a new resistor/ or sending unit.
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[chevy72blu]

Currently having the same issue with mine. I am 100% sure that everything is wired correctly. Upon closer inspection, the printed circuit seems to have shorted and is a bit burnt going to the gauge.

May be worth taking a look at.

I can confirm that the sender supplied with Boyd's is the correct 0-90 ohm.

[Roger71SWB]

After turning the key off Remove the center wire at the sender and then turn the key on your fuel gauge should go past full, then put the same wire to a good ground it should go to empty if this works your gas gauge and line back to the fuel gauge is good and you know you either have a ground problem at the sender or the wrong OHMS value of the sender, or the sender is bad.

[K10Dream69]

Originally Posted by Roger71SWB

After turning the key off Remove the center wire at the sender and then turn the key on your fuel gauge should go past full, then put the same wire to a good ground it should go to empty if this works your gas gauge and line back to the fuel gauge is good and you know you either have a ground problem at the sender or the wrong OHMS value of the sender, or the sender is bad.

thanks everyone for the information, so I finally got around to playing around with it again today and I took the fuel leveler out, and ran a temporary ground and moved the float up and down and the gas gauge is reading right. So I hooked it back up to the the original connections and held it above the fuel cell and the same thing hapened. Its reading properly when I move the float.

Here's the mind boggling part. When I place it back in the fuel cell to mount it, it goes way past full again. There's about 6-7 gallons out of the 17 gallon capacity.
So it seems my wiring works correctly until I try to mount it. How is this possible? This has literally delayed my progress two weeks now.

I don't have an ohms tester, sounds like I'm gunna have to get one.

Sorry for dragging this out. Its really frustrating
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[jorgensensc]

2 questions:
1st, when you moved the level arm up and down, did it appear to correspond with the gauge as far as level? Ex. Halfway up registers half a tank on gauge.
2nd, when you hooked the wires back up before putting it in the tank, when it worked the second time, did you use the new temp ground or the other ground you were using before?
I seriously think you have a grounding issue.
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[VetteVet]

Originally Posted by K10Dream69

thanks everyone for the information, so I finally got around to playing around with it again today and I took the fuel leveler out, and ran a temporary ground and moved the float up and down and the gas gauge is reading right. So I hooked it back up to the the original connections and held it above the fuel cell and the same thing hapened. Its reading properly when I move the float.

Here's the mind boggling part. When I place it back in the fuel cell to mount it, it goes way past full again. There's about 6-7 gallons out of the 17 gallon capacity.
So it seems my wiring works correctly until I try to mount it. How is this possible? This has literally delayed my progress two weeks now.

I don't have an ohms tester, sounds like I'm gunna have to get one.

Sorry for dragging this out. Its really frustrating
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You solved your own problem when you ran the temporary ground and the gauge worked. When you mounted the sender back in the tank you lost the ground. Either you changed wires like Jorgensensc said or the sender flange is insulated from the tank body, or possibly the tank is not grounded back to the battery. Connect the temporary ground wire back on the sender flange and see if the gauge reads the right amount.

[K10Dream69]

so I know its been awhile the latest update because I couldn't get it to work, I contacted Boyd welding about the issues I was having. They told me that the fuel leveler was from classic instruments after calling classic instruments describing the situation they told me to send it in and they would test it.
just got the call today, turns out the leveler was bad. talk about a waste of time and a month of holding a project up.

on a positive note they're going to send me a replacement one at no cost to me. So I can't complain.

Thanks for everyones advice though

Jon
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[SS Tim]

That is an unexpected turn of events. The level sender worked outside the tank but not mounted wounder what the root problem is, did they tell you? But you have or will have a new sender soon so that is a good thing.