I replaced my fuel pump and sending unit, Gauge still not working

As with many Chevy products, the fuel pump has the fuel level sending unit all-in-one. Replace the pump. Nothing related to the fuel gauge in the engine compartment.

Remove the fuel tank, and the pump is on the top side. Do not use cheap replacement from OReilly's or AutoZone...only use NAPA or OEM Chevy part.

The power wire from the sending unit runs to the gauge. Since it is showing 3/4 all the time. It is a break in the wire or really high resistance. I would check resistance of the ground wire first. If it is good(less than 5.0 ohms), I would replace the power wire from the pump to the gauge. I assume the gauge goes to empty with the key off. If not the gauge is bad.

Spencer, Check all fuses ,plugs and grounding at the tank.The sending unit module, inside the GM's gas tanks were notorious for going bad in this err, when you changed it did you use a quality part? Also the fuel pump sending unit plug/wire harnesses were known issues, so much that replacement pumps would often come with replacement plug to splice into existing harness. Check the attached links,instruction and guides on how to trouble shoot fuel gauge/sending unit, Good luck
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General Motors Fuel Gauge Troubleshooting American Autowire
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Fuel Gauge Tech How To Properly Diagnose Faulty Fuel Pump Sending Unit
GM Fuel Pump Level Sensor Diagnosis Testing

Did you replace the sending unit with the pump ?
The sending unit may have failed, or you may have a wiring problem between the sending unit and the gauge.

if it worked for a short period of time after doing the pump/sending unit the check the connections going to the pump/sending unit they would have been moved around doing the pump

Hello John.
The Montana/Venture vans have a problem with the fuel gauge sending units in the early 2000's.
The only cure is to drop the fuel tank, remove the sending unit and replace it.
The fuel gauge sending unit is available separately from the fuel pump.
Thank you for using FixYa.
KL

this problem is caused by a defective fual gauge sending unit inside the gas tank.

Usually thats a bad sending unit, replace the whole pump unit and should be good again...if the guage is always pegged in one spot then chances are there is a short

You don;t say whether the fuel gauge is reading accurately, or whether it's always on empty. If the gauge is always showing empty, it's most likely a problem with the sending unit in the fuel tank. Check the resistance across the two terminals of the sending unit.

On a C900, the fuel sender level unit is separate from the fuel pump and located on the right side top of the tank, accessible by removing the trunk floor lift up panel (the pump is located on the left side top of the tank.
Possible problems are: electrical line off or broken, float not working (it's fairly delicate); or gauge not working.

Test the resistance of the sending unit with the lines disconnected, the resistance should be 2.6 to 3.8 ohms full tank, 63.3 to 67.5 ohms empty tank; and test for voltage across the top of the sender unit, if no voltage, that's likely the problem!

If the gauge is otherwise reading accurately (showing 'full' for a full tank, etc) then the problem is likely a gauge malfunction and can be simply replaced.

Good luck!

Saabreur

The nature of the gauge is that it should behave with a linear taper between full and empty. If it works when full but then malfunctions as the level drops, the variable resistor in the sending unit which is housed along with the fuel pump in the gas tank is almost certainly at fault. The sending unit will have to be replaced to fix the problem. Expect this to be an expensive endeavor.