Chevrolet Silverado: In-tank fuel pump and fuel level sender failure (GMT800 Vortec V8)
In-tank fuel pump and fuel level sender failure (GMT800 Vortec V8) is a common engine fault on the Chevrolet Silverado on the 1999–2006 cars, and we rate it major. Putting it right costs $700 to $1,600 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 14 documented faults on the Chevrolet Silverado.
- Vehicle
- Chevrolet Silverado
- Engine
- 4.2L / 5.0L / 5.3L / 5.7L / 6.0L / 6.2L / 6.6L / 7.0L
- Years
- 1999–2006
- Fuel
- petrol
- System
- Engine
What you are looking at
No photograph available
What goes wrong
The fuel pump module in the tank of GMT800 petrol trucks is a well-known failure item: the sender's resistor contacts wear or corrode so the fuel gauge reads wrong, and the pump itself weakens until it cannot hold the pressure the Vortec engines need, causing lean running codes, stumbling under load and eventually a no-start. The gauge and pump are one module, so replacing either usually means the whole assembly. Access is by dropping the tank or lifting the tray, which is why labour makes up most of the cost. Note a wrong fuel gauge can also be the cluster stepper motor problem.
What you would notice
- Fuel gauge erratic, stuck or low fuel light on with fuel in the tank
- Long crank before starting
- Stumbling or loss of power under load or uphill
- Whining from the rear of the truck
- Check engine light for lean codes
How to check it
Where to look. Fuel pump module inside the fuel tank, between the chassis rails under the tray
Turn the key to ON without starting and listen near the rear of the truck for the pump to hum for about two seconds; silence or a loud whine is suspect.
Start the engine and note whether it fires quickly or cranks for several seconds.
On the test drive, accelerate firmly up a hill and feel for any stumble or surge.
Compare the fuel gauge reading with the seller's account of how full it is, and check the needle sweeps at key-on so you can separate a sender fault from a cluster fault.
Ask when the fuel pump was last replaced.
If a workshop inspection is possible: have fuel pressure measured with a gauge on the fuel rail (these Vortec engines need roughly 55 to 62 psi) and any lean codes such as P0171 and P0174 read with a scan tool.
What it costs to put right
$700 to $1,600 at New Zealand independent workshop rates. That is for this job on its own, not for the car.
Ask the seller
- “Has the fuel pump ever been replaced?”
- “Is the fuel gauge accurate?”
- “Does it ever hesitate or struggle to start?”
Now check the Chevrolet Silverado you are actually looking at
Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.
Where this comes from
- BobIsTheOilGuy forum thread 'Gas gauge problem' (GMT800 fuel level sender)
- Expedition Portal forum thread 'GMT 800 Fuel Pump - Preventive maintenance?'
- CarComplaints.com 1999 Silverado fuel gauge system complaints
Chevrolet Silverado buyer questions
Is in-tank fuel pump and fuel level sender failure (gmt800 vortec v8) serious on a Chevrolet Silverado?
We rate it major and common on the Chevrolet Silverado. The fuel pump module in the tank of GMT800 petrol trucks is a well-known failure item: the sender's resistor contacts wear or corrode so the fuel gauge reads wrong, and the pump itself weakens until it cannot hold the pressure the Vortec engines need, causing lean running codes, stumbling under load and eventually a no-start. The gauge and pump are one module, so replacing either usually means the whole assembly. Access is by dropping the tank or lifting the tray, which is why labour makes up most of the cost. Note a wrong fuel gauge can also be the cluster stepper motor problem.
How much does it cost to fix on a Chevrolet Silverado?
$700 to $1,600 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.
Which Chevrolet Silverado years are affected?
Our research records this fault on the 1999–2006 Chevrolet Silverado. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.
How do I check for it before I buy?
Turn the key to ON without starting and listen near the rear of the truck for the pump to hum for about two seconds; silence or a loud whine is suspect. Start the engine and note whether it fires quickly or cranks for several seconds. On the test drive, accelerate firmly up a hill and feel for any stumble or surge. Compare the fuel gauge reading with the seller's account of how full it is, and check the needle sweeps at key-on so you can separate a sender fault from a cluster fault. Ask when the fuel pump was last replaced. If a workshop inspection is possible: have fuel pressure measured with a gauge on the fuel rail (these Vortec engines need roughly 55 to 62 psi) and any lean codes such as P0171 and P0174 read with a scan tool. Look here: Fuel pump module inside the fuel tank, between the chassis rails under the tray