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Thu May 15, 2003 7:38 am

I've always had this problem with my gas gauge and just ignored it, but I am tired of looking down to see if the needle has finally broken off. The needle will record the correct level when full (or pretty close/a little below full) and rest at the proper level for a few seconds, then it jumps around real hard, banging itself from the left to the right, sometimes while sitting still, other times while driving. It does this continuously. Sometimes I feel as if it is the fuel level shifting in the tank and the gauge overreactin, but I'll come to a complete stop and even after the fuel has a chance to calm down the needle bangs around like it wants to get out. Anyone with an answer?

Thanks,

Doug

Thu May 15, 2003 7:43 am

Just a thought but since the sender uses resistance to operate it might just not be getting good contact. Maybe if you take it out and clean the contact where the wiper brush rides, it might fix it. I know its no easy task to get in there a pull it out. -Jeremy

Thu May 15, 2003 7:45 am

maybe you have a bad ground. try pulling out your guage and sanding the backside of the dash where the bracket that holds it in presses against the back of the dash, that is where the guage gets its ground.

Thu May 15, 2003 7:52 am

I agree with rizzag, sounds like a bad ground. You also have two wires that go into the gauge, a positive that is only active when the key is turned on, and the sending unit wire which regulates the needle. Clean all the contacts including what rizzag said. Also, clean the ground connection in the engine compartment and the sending unit connection that goes back up to the cab.

mike

Thu May 15, 2003 8:06 am

Jeremy,

What is the wiper brush? Is this a contact inside the guts of the gauge? I will clean all the contacts first and see if that does it.

Thanks,

Doug

Thu May 15, 2003 8:35 am

Definately try the easy to reach stuff first. The part I was refering to is in the tank. The resistance on a sender is created by a "brush" the sweeps back and forth on some sort of contact to varie the resistance therefore makeing the needle rise or fall. Sometimes the contact looks like a spring as in the resistor inside the dash dimmer switch on the later buses. Anyway if the contacts on the back of the gauge itself are clean and have good contact, the last resort would be to pull the sender out of the tank and clean it thoroughly with some electrical contact cleaner and a gentle wire brush. -Jeremy

Tue May 20, 2003 3:01 am

What sender do you have in your tank? and what gauge are u using 6v or 12v?

Tue May 20, 2003 6:58 am

I pulled the gauge which is 6 volt and cleaned all contacts thoroughly. When the key is turned but the engine not started, the needle goes to the appropriate place on the gauge and sits still. When the engine is fired up the needle starts to jump and when the bus begins to move the needle goes nuts. It calms down a little when the bus is at a stop (indicating that the movement of fuel in the tank is probably triggering the sender). I'm not going to pull the engine to get at the sender at this point. Too bad they aren't reachable.

Doug

Tue May 20, 2003 7:59 am

It sounds to me then that you have may not have a constant 12v connection going into the gauge. Pull that wire and put your test light or volt meter on it and see if there is a fluctuation. Do any of your lights flicker? Are you running a generator or an alternator?

Tue May 20, 2003 8:46 am

This is isolated to the gas gauge. Nothing else in the bus fluctuates. Voltmeter for voltage is constant. The resistance in the sender is doing the fluctuating. Must have a break in the coil in the sender.

Tue May 20, 2003 9:26 am

The sender is made of two very small wires and a float that rides up and down on them as the float rises the resistence is less thus the guage reads a higher level as the float moves down the resistence increases and the guaage reads lower, some wear you have a bad connection the float may have come off on of the wires and is making intermittent contact, this does not happen often but does happen, I would check all of your connections first including the guage bracket ground befor pulling the sending (a real pain in a bus, easy in a singlecab) if you pull the sender be carefull they are very fragle take of the little nut on the bottom and pull it apart make sure the little wires are in between the clips on the float and that the wire has good connection at both ends, I had a sender that the rivit was not making a good connection I removed the rivit and replaced it with a pop rivit and it works great now. hope this helps if you have anymore questions email me and I will try to help.

Tue May 20, 2003 12:53 pm

Brett,

I put a voltmeter on the sender wire with the key on and the motor not running (car very still in the garage). The needle was very still and registered properly. When I rocked the car just a little (motor still not running) the needle went nuts and the ohm's reading went all over the place. When I grounded the sender wire the needle went to full and held steady, so the gauge is fine.

Tue May 20, 2003 8:12 pm

I had a similar problem, jumpy gas guage needle, but when i turned on my headlights and the panel light came on, the needle pegged past the full mark (so if I was short of gas, just turn on the lights and voila, full tank :) ). Today while home with my daughter (she was sick) I ran a ground wire from one of the two bolts behind the gauge to a real good ground (where my flasher unit is grounded) and the needle stopped jumping around and will measure correctly with the lights on.

I suspect your ground. I've found that a majority of the electrical problems in my bus have been grounding related.

Turbo_g
66 Custom Kombi

Wed May 21, 2003 5:50 am

G_turbo,

Been there, done that. My grounds are solid. Did the jumper wire, sanded all ground surfaces to raw metal etc. The needle now is changing readings, going from 1/4 tank to 1/2 tank depending on how much I slosh the tank while sitting still.

Wed May 21, 2003 7:08 am

It sounds like you have a problem with the float in side the sender, your float may have come off the wire, the guage should not jump around just from rocking the Bus, remember the float is inside of the tube and there are only small holes to let fuel in it, that is to keep the float from rising up and down to quickly, if your float has come off the wire it is making poor and intermittent contack and the guage will react crazy to this because of the fluctuating resistance, So if you are sure on the grounds than you may need to remove the sender, I think you have to romove the tank on a Bus to do this I hope for your sake this is not true. One other thing, do you have any problems with the gas tank venting properly, if your tank is not venting it is colapsing and you may actually be bending the sender it only takes a little bend to effect the sender as the wire will touch the inside of the tube, this actually happened to me on my Singlecab, had to install a new tank, the bottom was pulled up about 3 inches, the sides were bent in and the top was pulled down, amagine my surprise when I took of the gas tank covers and saw this, I made a venting system for the new tank and it works great, if anyone wants to know how I made it I will be happy to explain it.

Tue Aug 23, 2011 10:02 am

Mine was jumping like crazy even after putting a brand new sender....Took out the gauge, brushed off the two connections with a wire brush; put it back in and Shazam ! ! ! Takes all it took....Needle works correct....

Thu Aug 25, 2011 6:09 am

Update.....Tank was full so false info on my last test....Now that the fuel level is down, it started jumping again....So, I started messing with running a ground wire from the gauge and :oops: something melted :oops: Now the gauge does nothing....Jumpy was better than nothing.... :evil:

Thu Aug 25, 2011 7:58 am

Jumpy is most likely the contacts inside where the float's ends touch the ni-chrome wire.

Fri Aug 26, 2011 8:33 am

I just installed a new sender a few months back...What should I do?

Fri Aug 26, 2011 9:48 am

If it's the tube type sender then pull it out and open it up. Slide the float up and down and see if that works it normally. Make sure it's grounded at the float flange.