Long story short,my truck broke down at Island beach state park.Iwas having a problem with fuel pressure.I started poking around with my test light at my fuel pump wires.My fuel gauge all of a sudden went past the full mark and got stuck at 5 oclock position.I towed the truck to the local garage.They put in a new FP relay and a new Fuel pump.They did not replace the float assembly because I just put a new Spectra pump and assembly only 2 months ago.So I know the float is new,so what would make my gauge be stuck at the 5 o'clock posision?
CK5
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fuel gauge stuck at 5 o'clock position
- Thread starter starfish
- Start date
bad ground
my fuel hanger assembly only has one ground wire and its grounded right to the frame.also the new ump is working.I poked my test light through the pink wire that goes to the gauge.When I hold the test light on the wire,the gauge works like it shound .As soon as I take off the test light,the gauge goes back to 5 o'clock.any ideas?
herkdriver007
1/2 ton status
Try moving your ground
British Slave
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The most common cause of gas gauge trouble is a poor ground, especially at the tank sender unit. It is important that all wiring connections are clean and tight, and free of dirt and corrosion. A poor ground or loose connection to a gas gauge is just as likely to cause problems as loose or dirty battery cables assuredly will with your starting system.
For example, if the gas gauge needle remains on empty when the ignition key is turned to the "on" position and you are sure the gas tank is partially full, battery current may not be reaching the gauge. To check further, connect a jumper wire between the ignition switch and the dash gauge. If the gauge now works, replace the defective wiring between the gauge and the ignition switch.
If the gauge needle remains stuck in one place, try turning the ignition switch off and on several times in succession. This will allow you to determine if it is the dash gauge or the tank sending unit that is defective. If turning the ignition switch off and on (a half-dozen times is a good test) does not seem to help, and you've verified that the dash gauge is receiving power, try the following troubleshooting steps:
A functioning sending unit will have a high resistance when the tank is full and a low resistance when the tank is empty. If the gauge reads higher than it should, make sure the wire attached to the electrical terminal on the tank sending unit is making a good ground connection. If necessary, clean the connection and reinstall the wire to the terminal, then check the gauge operation. If that didn't fix the problem, use a jumper wire to ground the electrical terminal on the tank sending unit to the tank unit housing (leave the wire to the gauge connected to the tank unit). Turn the ignition switch on. If the gauge reads empty or below empty, the sending unit is defective.
If the gauge still reads high, try grounding the tank unit electrical terminal to a clean portion of the frame. If this brings the gauge to empty or below, the tank unit is OK, but there is a bad ground between the gas tank and the body or chassis (or less likely, between the tank unit and the gas tank). Either way, find and correct the bad connection or merely run a permanent jumper wire from the frame to one of the screws holding the tank sending unit to the tank.
If the gauge still reads incorrectly, the wire from the tank unit to the gauge may be faulty. Check by using a jumper wire to ground the tank unit terminal on the gauge (the one not connected to the ignition). If the gauge now reads empty or below, the problem is in the wire leading to the tank (or its connection to the gauge). If grounding the tank terminal still doesn't cause the gauge reading to drop to empty or below, the gauge is faulty.
When the gauge reads lower than it should, check at the gauge by disconnecting the wiring from the tank unit. Turn the ignition on and if the needle reads full or above, the gauge unit is probably good and the tank unit or the wiring leading to it are probably the problem. Reconnect the tank unit wire to the gauge before proceeding.
The next trouble-shooting task begins by disconnecting the wire to the tank sending unit. If the gauge still reads full, there is likely a short to ground somewhere between the sending unit and the gauge. Look for worn insulation allowing the wire to contact the body or frame. If the gauge reads full or above with the wire disconnected, the problem is in the tank unit rather than the wiring. It could be an electrical fault, or the float may be stuck or may have sunk because of a hole caused by corrosion. Remove the tank sending unit and check it. If the float is bad, you'll likely hear gas sloshing around in it or see gas dripping out. If the float is OK and the float arm seems to be swinging freely through its full range, replace the tank unit.
Ground the gas tank terminal post of the tank sending unit using a jumper wire. If the dash gauge now reeds empty, the gas tank unit is defective. If the dash gauge needle fails t move, the dash gauge is defective.
If the gas gauge works, but reads lower than it should, check for defective wiring between the gas gauge and the tank sending unit. Also check for a poor ground at dash gauge and the sending unit by using a jumper wire. If the dash gauge reads empty when the tank is actually half full or greater, the wiring between the dash gauge and the tank sending unit is defective. Disconnect the wire at the gas tank sending unit terminal. If the gas gauge reads still reads empty, the dash gauge unit is defective.
For example, if the gas gauge needle remains on empty when the ignition key is turned to the "on" position and you are sure the gas tank is partially full, battery current may not be reaching the gauge. To check further, connect a jumper wire between the ignition switch and the dash gauge. If the gauge now works, replace the defective wiring between the gauge and the ignition switch.
If the gauge needle remains stuck in one place, try turning the ignition switch off and on several times in succession. This will allow you to determine if it is the dash gauge or the tank sending unit that is defective. If turning the ignition switch off and on (a half-dozen times is a good test) does not seem to help, and you've verified that the dash gauge is receiving power, try the following troubleshooting steps:
A functioning sending unit will have a high resistance when the tank is full and a low resistance when the tank is empty. If the gauge reads higher than it should, make sure the wire attached to the electrical terminal on the tank sending unit is making a good ground connection. If necessary, clean the connection and reinstall the wire to the terminal, then check the gauge operation. If that didn't fix the problem, use a jumper wire to ground the electrical terminal on the tank sending unit to the tank unit housing (leave the wire to the gauge connected to the tank unit). Turn the ignition switch on. If the gauge reads empty or below empty, the sending unit is defective.
If the gauge still reads high, try grounding the tank unit electrical terminal to a clean portion of the frame. If this brings the gauge to empty or below, the tank unit is OK, but there is a bad ground between the gas tank and the body or chassis (or less likely, between the tank unit and the gas tank). Either way, find and correct the bad connection or merely run a permanent jumper wire from the frame to one of the screws holding the tank sending unit to the tank.
If the gauge still reads incorrectly, the wire from the tank unit to the gauge may be faulty. Check by using a jumper wire to ground the tank unit terminal on the gauge (the one not connected to the ignition). If the gauge now reads empty or below, the problem is in the wire leading to the tank (or its connection to the gauge). If grounding the tank terminal still doesn't cause the gauge reading to drop to empty or below, the gauge is faulty.
When the gauge reads lower than it should, check at the gauge by disconnecting the wiring from the tank unit. Turn the ignition on and if the needle reads full or above, the gauge unit is probably good and the tank unit or the wiring leading to it are probably the problem. Reconnect the tank unit wire to the gauge before proceeding.
The next trouble-shooting task begins by disconnecting the wire to the tank sending unit. If the gauge still reads full, there is likely a short to ground somewhere between the sending unit and the gauge. Look for worn insulation allowing the wire to contact the body or frame. If the gauge reads full or above with the wire disconnected, the problem is in the tank unit rather than the wiring. It could be an electrical fault, or the float may be stuck or may have sunk because of a hole caused by corrosion. Remove the tank sending unit and check it. If the float is bad, you'll likely hear gas sloshing around in it or see gas dripping out. If the float is OK and the float arm seems to be swinging freely through its full range, replace the tank unit.
Ground the gas tank terminal post of the tank sending unit using a jumper wire. If the dash gauge now reeds empty, the gas tank unit is defective. If the dash gauge needle fails t move, the dash gauge is defective.
If the gas gauge works, but reads lower than it should, check for defective wiring between the gas gauge and the tank sending unit. Also check for a poor ground at dash gauge and the sending unit by using a jumper wire. If the dash gauge reads empty when the tank is actually half full or greater, the wiring between the dash gauge and the tank sending unit is defective. Disconnect the wire at the gas tank sending unit terminal. If the gas gauge reads still reads empty, the dash gauge unit is defective.
Thanks for all the good info!My gauge has power to it.I took off the plastic covering the gauge.When I move the needle with my finger to the 3/4 full mark it wont stay it goes right back to the 5'oclock position.It seems like its drawing too much juice.when I touch the gauge wire goin to the tank with the test light,my gauge is perfect,but as soon as I take off the test light the gauge goes back up to past the full mark.
OK,I grinded the frame right down to the good stuff and ran a second ground off the wire from the pump assembly.I got 2 good grounds and the same problem.Is it posible that the float and sender went bad when the pump burned out.This is a new Spectra pump and float assembly that I bought in Feb.(3 months old).The pump went bad on memorial day,and at the same time the gauge went funky on me!I was stuck at seaside park for 2 days.And I still couldnt find any stripers!
British Slave
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OK, Is the truck running? The gauge stopped working after a shop installed a new pump, right?
At this point I think you will need to pull the sending unit/pump assembly and bench test the sending unit. Maybe there was an installation issue?????????
Where did you buy the sending unit/pump? It may have warranty.
At this point I think you will need to pull the sending unit/pump assembly and bench test the sending unit. Maybe there was an installation issue?????????
Where did you buy the sending unit/pump? It may have warranty.
I think the float on the sender might be stuck.
Or the sender is not compatible with the gauge.
Or the sender is not compatible with the gauge.
Try measuring the resistance from the sending unit to the frame. Should be between 0 - 100ohms. If it is infinite, the resistor in the tank may be burned up or the wires disconnected.
When you hook your test light up, the gauge is likely measuring the resistance of the light bulb. That is why the gauge moves.
When you hook your test light up, the gauge is likely measuring the resistance of the light bulb. That is why the gauge moves.
The gauge went bad when I broke down and started poking the 2 wires going to the fuel pump along the frame.When i broke down ,the truck was towed to a shop and they replaced the relay and pump only.the float is only 3 months old and i checked to see if it was hung up.The gauge moves to half a tank when I put the test light to the float wire,when I remove the test light from the float wire the gauge goes back to 5 'oclock position.could be gauge is bad?I have good grounds and I checked the wires from pump to fuse box.
lectric80
3/4 ton status
Follow russell's advice on using the multi-meter to test resistance to ground. Normal GM resistance is 0-90 ohms, if it is not in spec the sending unit is suspect, if it is in spec it is probably the wire going to the gauge. Seems odd that a pump would fail so quickly, and that leads me to believe the sending unit is also bad.
You have already proven the gauge is good with your test light. If your ground is good then the only other possibility is a fried sending unit. You likely sent 12V through it when you were poking around when the truck died on the highway and burnt it up, I've done the same thing by accident before. 3 months old and a pain in the butt to change, but I am 80% sure it is your problem
I did exactlly that!I think I fried the sending unit,I was trying to run a hot wire from the battery to the pump and I touched the hot wire to the float wire by accident,thats when I noticed the gauge shot past the full mark.
