# no gas gauge



## the eggman (Nov 17, 2009)

I have a 2000 k 3500 dully with 2 gas tanks.
My gas gauge quit working. I would think the
sending unit in the tank is bad but since i have
2 tanks I am not sure because I would think 1 would
still be working. I do not know how a lot about how the 
2 tanks work. But I do know that their is no switch
to change tanks and the gas gauge would read both tanks 
together . Any input on how the tanks work or any thoughts 
about how to fix it would be great.
Thanks,


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## JpLawn (Aug 5, 2007)

I have a 99 3500 the same way. There is a transfer pump on the frame between the tanks. The back tank is pumped in to the front tank and then to the motor. We have gone through 10 fuel pumps since it was new. Change the front pump and you should be fine. Ours doesn't work any more and the needle feel off in the dash. So we just us the front tank and watch the mileage. Good luck


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## CGM Inc. (Dec 15, 2008)

Same here, watch the mileage and fill up often to be on the safe side!


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## MickiRig1 (Dec 5, 2003)

I had new lines mig-ed on to the rusted off ends on my sensor plate. ( My F-250 ) They replaced the level sensor board. Too bad they put the wrong one in! It would read 3/4 when empty and 1/4 when full. I had sealed the hell out of the sensor ring and had no desire to remove it to get it right. I never put gas in it for 3 months! The Wife could not remember how it worked. She would throw $10 in it every time She drove it.


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## the eggman (Nov 17, 2009)

I still would like some more thoughts 
on how to fix the gas gauge.
Thanks all


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## Brian Young (Aug 13, 2005)

Here's my thoughts on it! They are a crap design period. My 00 GMC has done this since we bought it. Its left my guys stranded and left the repair shop with plenty of $$$$ in their pockets. Its been to 3 different shops to fix this problem and no one can get it right. So far we've replaced sending unit, replaced numerous wires. (there is a set of wires that come into a big junction on the driver side frame right at the end of the cab that has tons of wires to the fuel system, mine were junk) Well the first time out this year and guess what, "hey Brian this thing is spitting and sputtering" the fuel gage read 1/8. So all we're going to do is after about 2 hrs of plowing and an hour or so of salting is just going to keep it topped off and see. This spring its gone! Ive put so much money into this thing that I hate to get rid of it but I just dont have the time to fix it right.


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## Snowguy01 (Jul 23, 2007)

I have a 02 and the same thing happened to me and did it again I replaced the front fuel pump and unit and now the back quit working my gas gauge only reads full the back tank is full it only sucks out of the front and let me tell you it sucks. Every 100 miles we fill it. I wish some one could get it right and fix it.


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## MickiRig1 (Dec 5, 2003)

Does the system when it works read the level of each tank? I would think it would be the switch that selects the tank you use or the gage it's self.Since both are not working. You also need to make sure the ground that leads to the tank is good. Most systems ground under the hood and lead to the tank. Check all the wires, might even replace the pig tails that go to the tanks. They can take abuse from ice building up on them and stressing them. Pull them off the sensor plate connection and spray the connections with cleaner and put dielectric grease in them. Make sure all the connections on the system involved has it done. Inspect all the connections, I bet you will find the problem.


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## auto tech (Nov 30, 2010)

it needs a fuel sender its in the front tank,the when the fingers break off the gauge flutters with only 1 and when they both brake it no longer works.


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## Brian Young (Aug 13, 2005)

auto tech;1137602 said:


> it needs a fuel sender its in the front tank,the when the fingers break off the gauge flutters with only 1 and when they both brake it no longer works.


What do you mean by "fingers"? Mine originally fluttered then we replaced the whole sending unit etc. and the gage still flutters.


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## auto tech (Nov 30, 2010)

there are 2 tabs on the level sensor that measure resistance as the tank fills or empties and when they break off which they all do it same sender cars and trucks this happens but i suspect your fuel sending unit was replaced with out a level sensor you have to transfer it off the old pump if it was a gm pump(sending unit) i did write sender sry i meant level sensor


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## STIHL GUY (Sep 22, 2009)

id keep a 5 gallon tank in the bed just incase you run out and need to get to the gas station


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## Ant118 (Feb 8, 2011)

Mine 2001 2500HD is doing that. Im thinking its the sending unit? I was sort of working and now fluttering. Checked if it was a ground and its not. So im not sure?


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## brad96z28 (Aug 21, 2005)

auto tech;1137988 said:


> there are 2 tabs on the level sensor that measure resistance as the tank fills or empties and when they break off which they all do it same sender cars and trucks this happens but i suspect your fuel sending unit was replaced with out a level sensor you have to transfer it off the old pump if it was a gm pump(sending unit) i did write sender sry i meant level sensor


Some people should try checking parts before replacing them.


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## ticki2 (Jan 10, 2006)

Ant118;1238804 said:


> Mine 2001 2500HD is doing that. Im thinking its the sending unit? I was sort of working and now fluttering. Checked if it was a ground and its not. So im not sure?


Could also be the instrument cluster . Each gage has a stepper motor and they frequenty go bad.


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## REAPER (Nov 23, 2004)

STIHL GUY;1138801 said:


> id keep a 5 gallon tank in the bed just incase you run out and need to get to the gas station


Had a 88 that did this and that is exactly what I did. (6 gall actually)
These days you better use a cable lock to lock it in the bed tho or it would be gone the first time you parked and walked away from it.


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## RichG53 (Sep 16, 2008)

Where can I find the Ground wire ??? To check first...

I get sporadic reads on and off ...


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## damian (Jan 29, 2009)

best way to fix this is with a tech 2 scan tool,you can operate the dash gage and confirm operation,you can view front and rear tank levels and locate faulty sender.if no scan tool you have to do it the hard way,ground each fuel sender and watch fuel gage,grounding each should show 1/2 ground both you get full,if the senders dont work,fuel wont transfer from rear to front.this system uses a fuel module to average tank readings and transfer fuel,it is located on drivers frame rail,this system is not bad to diag if you follow the diag routine in alldata or a gm service manual.tough without the info.good luck


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## RichG53 (Sep 16, 2008)

Still would like to know where to look(find) the ground wire ...
It is a bit tight to see which is which..
I'm thinking that may be my problem with sporadic reads (usually after a fill up)..
Thanks !!


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## Ant118 (Feb 8, 2011)

RichG53;1242351 said:


> Still would like to know where to look(find) the ground wire ...
> It is a bit tight to see which is which..
> I'm thinking that may be my problem with sporadic reads (usually after a fill up)..
> Thanks !!


I believe its the purple wire that is attached to the sending unit.


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## MickiRig1 (Dec 5, 2003)

The other end of the ground is under the hood. Might clean and protect with dielectric grease every black wire connected to the body, engine or frame. This can correct or prevent many problems.


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## matzke3 (Oct 15, 2008)

I had a customer come in with a late 90s or 2000 3500 hd box truck with no fuel guage. This truck had the pump that pumped fuel from the rear tank to the front. Theres a module that controls everything behind the cab ner the lh rail. Its a small plastic box. Replaced it and everything worked.


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## RichG53 (Sep 16, 2008)

MickiRig1;1245255 said:


> The other end of the ground is under the hood. Might clean and protect with dielectric grease every black wire connected to the body, engine or frame. This can correct or prevent many problems.


Under the hood where ????


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## JTVLandscaping (Jan 1, 2010)

My '99 with a single tank had a problem with the guage. The gauge stopped working, I always assumed it was the sending unit. Then the fuel pump went and I replaced the whole unit and that corrected the problem. I never worried much about the gauge since I just always made sure the tank was full. All I know about it is the problem was in the tank.


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## MickiRig1 (Dec 5, 2003)

The wire harness runs down the left side of the truck. Under the hood the ground will be bolted or screwed on that side under the hood. Black wires attached to the engine or fender is what you clean up and dielectric grease. Even if it's not the problem at-least you know that part is good. You should check and protect all the ground wires every season. It prevents many problems.


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## RichG53 (Sep 16, 2008)

MickRig 1;1260067 said:


> The wire harness runs down the left side of the truck. Under the hood the ground will be bolted or screwed on that side under the hood. Black wires attached to the engine or fender is what you clean up and dielectric grease. Even if it's not the problem at-least you know that part is good. You should check and protect all the ground wires every season. It prevents many problems.


Do you maybe mean Frame instead of fender ???

I would still like a better description of what wires to look for at the tank (ground)..
There are several there and rather tight..

Mine works just not right after a fill up or sporadically ( driving full tank ) some times goes to empty then bounces back to where it was but does not always do that..
Also if tank is full when first starting it will read empty until restart or shack trk a little..
It seems that after some gas is used it does not react that way..

So I am a puzzled..


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## MickiRig1 (Dec 5, 2003)

The grounds are attached to fenders,engine and the big one off the battery. They supply the ground leads under the hood because they don't get dirty as fast. It's just good maintenance to make sure they are clean and protected. You may have a bad sensor plate in the tank. They put a capacitor in the circuit to feed voltage so the gage does not swing. So this kinda tells me the plate is bad. But I always start checking the wires.If it's a duel tank system the switcher may be bad. They sell the pig tail to the tank for a reason. They go bad, the plug get's crud in it and connection is lost.


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## bsmitty (Jun 27, 2010)

I kind of have the same problem with my 2000 GMC 3500HD dump. My fuel gauge has been working on and off for the last 4 months and a few weeks ago it stopped working all together. The other day I went to put gas in and my front tank took fuel, but my rear tank would not. It stopped like it was full. So my question is why is my rear tank not sending fuel to the front and why is my fuel gauge not working at all? I believe it is the sending unit in the rear tank but I don't know how to rule out the transfer pump on the frame rail. With the gas gauge not working it tells me it is the sending unit, but I don't know if that doesn't work will it not allow the transfer of fuel. Please halp if possible.

Thanks

Brian


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## MickiRig1 (Dec 5, 2003)

Most of the early fuel injected systems have a return line to the tank it took fuel out of. So if the tank switcher has a problem it will return fuel to the wrong tank. The switcher also changes the gage to the tank being used. So check the wires and lines on it. Look in the repair manual and see if it tells you how it switches tanks. I would bet the switcher has a problem.


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## truckboy (Jul 8, 2010)

I think this problem is because of defective Dash Voltage Regulator, if it is bad then replace the same or else check the voltage limiter.


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