Which parts fail
Components named in complaints (fuel pump, injectors, fuel tank, hybrid and EV propulsion).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 1999 GMC Sierra owners, lightly cleaned up (personal details are redacted by NHTSA).
Truck running sluggish. Difficult to start at times. Hooked up to computer a couple times and showed different sensors bad at different times. Driving to work on 7/7/2005 vehicle suddenly shuts down, able to pull into a resturant parking lot. Problem : fuel pressure regulator clogged ( this is a vaccum line no gas should go through it) causing gas to flow at 60 pounds fuel pressure into the intake manifold causing a fire. Because of this the manifold burned a big hole where #4 cylinder would be located. This happened while I was driving 55 MPH down the road & was possibly still burning while I waited in my vehilcle to be picked up. I believe this is a dangerous & should be looked at. My girlfriends nephew found the problem & replaced the intake manifold & fuel pressure regulator. …
Tl* the contact owns a 1999 GMC Sierra. While driving approximately 35 MPH on a four lane highway, the contact came to an abrupt stop and the brake pedal suddenly traveled to the floor without resistance. The vehicle was towed to an independent mechanic where the technician informed that the brake line quality was poor with inexpensive materials. The vehicle was repaired at the cost of $850. In addition, the fuel lines exhibited leakage due to excessive corrosion which was replaced on a separate occasion. The manufacturer was notified and they stated that there were no complaints filed on the brake line system. The failure mileage was approximately 60,200. The VIN was unavailable. Updated 06/16/11 the consumer also stated there was a problem with the fuel lines. Updated 06/21/11
The fuel gauge on my 1999 GMC Sierra ext. Cab does not work. It has never worked. I did not see the problem as urgent until my brother-in-law, who has the exact same truck, got stranded in Mexico because his fuel pump went out. He has had the same problem since he has had his truck and it cost him $300.00 dollars to change the fuel pump out. That was cheap because he did the work himself. I have done some research on the internet and have seen the same problem with several trucks of the same model and year. I went to the local dealership and there is no recall on the fuel pump for my truck and would respectfully request that the fuel gauge/pump for the 1999 GMC/Chevy 1500 truck be looked into for consideration for a recall.
Gas tank gauge works once in a while. Our mechanic said it was probably due to moisture. Also, the rear differential cover is either cracking or rusting through. I put a new gasket on it and the next day it was leaking again but not at the gasket. About 1/3 up from the bottom, you can see where fluid is leaking through the cover. I called 2 dealers (1 Chevrolet, 1 GMC). They both gave me numbers to other dealers (1 in pa., 1 in ia., 1 in upper mi.). The two out of state dealers told me that the part was for a customer and would not sell it. The one in mi. Also said that, in addition to "that must be a popular part, because I've had every dealer in the country call me." is this part a defective piece?
Dt*: the contact stated there were two problems with the vehicle. First, the fuel gauge worked intermittently, but the vehicle has not been inspected by the service dealer concerning this issue. There were no warning indicators prior to the intermittent failure of the fuel gauge. Second, the passenger window dropped into the door without warning. The vehicle was inspected by the contact and it was discovered a cable was broken that held the window in place. A shim was added to keep the window in stationary position.
Dt: the contact stated that the fuel gauge indicator iwasnot working correctly. When the fuel tank was filled up the gauge will move to empty, and the low fuel light will come on. After driving the vehicle for a while the gauge will move to full. But with continued driving the gauge will drop down to empty, and the fuel light will come on again. The service dealer stated that the sensor needed to be replaced. The contact had not replaced the sensor.
Tl* the contact owns a 1999 GMC Sierra. The contact stated that while driving various speeds, he smelled a strong gasoline odor inside of the vehicle. There was also fuel visible on the ground. The contact inspected the vehicle and noticed that both the fuel and brake lines were completely rusted. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the problem. The approximate failure mileage was 71,000.
Fuel pump/sending unit faulty. Gauge does not read proper fuel levels. One minute while going down road you have a full tank next minute light comes on fuel gauge reads empty. Sometimes gauge will not read fuel in tank at all. I have come across other GMC owners who have the same complaint. Guys at shop say it is common to replace the fuel pump/sending unit.
I was coming to a stop and I lost my brakes I was able to get it stopped. Took it to my mechanic right away and was told the brake line burst and hit my gas line busting it as well. They had the vehicle for over 3 weeks. They repaired the gas line easy enough but the brake line had to be completely replaced.
While on a trip gas gauge malfunctioned. The fuel gauge remained on 3/4 while the mileage was 335. When filling the tank it showed full after 4 gallons were delivered. The problem continued thereafter till present. The only way to know the fuel level is by the tripometer and guess work.
Fuel System complaints in other Sierra years
Frequently asked questions
How common are fuel system problems on the 1999 GMC Sierra?
NHTSA has 26 complaints about the fuel & propulsion system of the 1999 GMC Sierra, 4% of the model year's 600 complaints. The component named most often is delivery › fuel pump (4 mentions).
Is there a recall for 1999 GMC Sierra fuel system problems?
No. NHTSA lists no fuel & propulsion system recall for the 1999 GMC Sierra, though it has 5 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 1999 GMC Sierra fuel system problems start?
Half of the complaints with a recorded mileage happened before about 60,000 miles.
Is it dangerous?
Owners linked 0 crashes, 1 fire and 0 injuries to fuel & propulsion system problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.