1999 GMC C/K 2500 Problems: 3 Issues Every Owner Should Know

1999 model year · 210+ owner reports · Updated April 2026

According to Au7o's analysis of 210+ owner reports, the 1999 GMC C/K 2500 has 3 documented known issues, with 3 rated critical. The most serious are In-Tank Fuel Pump Failure ($250-$700 repair), 6.5L Diesel PMD/FSD Module Failure ($300-$2,500 repair) and Brake Line Corrosion and Rust-Through ($400-$1,500 repair). The most commonly reported issue is In-Tank Fuel Pump Failure with 210 owner reports. Across all issues, repair costs range from $250 to $2,500. DIY maintenance guides at au7o.io.

All 3 Known Issues

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210 owners

On the 1996-2000 GMC C/K 2500, the C/K 2500's in-tank electric fuel pump fails without much warning, stranding drivers. The pump works harder in trucks used for towing and in hot climates. Running the tank below 1/4 accelerates wear since fuel cools the pump.

Common Symptoms

Engine stalls while driving
Hard starting especially when hot
Whining noise from fuel tank area
Loss of power under load
Engine sputters at highway speed
No-start condition

How to Fix

Replace the fuel pump module assembly including the sending unit and strainer. Drop the fuel tank for access. Use an OEM or quality aftermarket pump — cheap pumps fail quickly in these trucks.

What Owners Are Using

Parts and tips from 210+ owners who fixed this issue

UpgradeOEM-quality fuel pump module (Delphi #FG0199)
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TipKeep the tank above 1/4 full — fuel cools the pump, and running low causes it to overheat and fail prematurely

Typical repair cost:$250 - $700

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Community Reported

High Confidence210 reportsLast reported by owners Mar 2026Reviewed Mar 2026

On the 1994-2000 GMC C/K 2500 6.5L Diesel, same 6.5L diesel injection pump PMD failure as Chevrolet C/K 2500. The Pump Mounted Driver overheats and causes stalling.

Common Symptoms

Stalling while driving
No start when hot
Hard starting

How to Fix

What Owners Are Using

Parts and tips from 0+ owners who fixed this issue

UpgradeBluetooth OBD-II scanner for reading engine codes and monitoring live data (BlueDriver Bluetooth OBD2 Diagnostic Scan Tool)
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UpgradeQuality synthetic oil and filter combo for engine maintenance (Mobil 1 Full Synthetic Oil and Filter Bundle)
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Typical repair cost:$300 - $2,500

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Medium Confidence0 reportsLast reported by owners Invalid DateReviewed Invalid Date

On the 1999-2003 GMC C/K 2500, same brake line corrosion issue as Chevrolet C/K 2500 and all GMT800 trucks. Steel brake lines corrode under securing clips on the frame rail, especially in salt-belt states. NHTSA investigated 6 million GMT800 trucks but no recall was issued. The lines can burst without warning, causing complete brake failure.

Common Symptoms

Soft or spongy brake pedal
Brake fluid pooling under vehicle
Low brake fluid warning
Visible rust and flaking on brake lines
Sudden loss of brake pressure

How to Fix

Inspect all steel brake lines from the master cylinder/ABS module to the frame rails and rear axle, paying close attention to areas hidden by plastic/metal retaining clips and above the fuel tank where rust commonly forms; if any line is heavily scaled, wet, or leaking, replace the entire affected line set rather than patching a single section. The preferred repair is a complete pre-bent stainless or NiCopp brake line kit with new fittings, followed by bleeding the full hydraulic system (including ABS if required by the scan tool/service procedure) and replacing any contaminated hoses or calipers/wheel cylinders found leaking. After repair, flush in fresh DOT 3 brake fluid, secure the new lines with updated clips or protective wrap to reduce future chafing/corrosion, and road-test for pedal firmness and proper ABS operation. Typical cost is about $800-$1,800 for full line replacement depending on rust severity, labor, and whether fuel tank removal or additional brake component replacement is needed.

What Owners Are Using

Parts and tips from 0+ owners who fixed this issue

UpgradePre-bent brake line kit for rust-free replacement (Dorman Brake Hydraulic Line Kit)
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UpgradeFlexible brake hose for caliper connection point (Raybestos Brake Hydraulic Hose)
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Typical repair cost:$400 - $1,500

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Frequently Asked Questions

What are the most common GMC C/K 2500 problems?

According to Au7o's analysis of 210+ owner reports, the 1999-1999 GMC C/K 2500 has 3 documented issues. The most frequently reported are: In-Tank Fuel Pump Failure, 6.5L Diesel PMD/FSD Module Failure, Brake Line Corrosion and Rust-Through. Of these, 3 are rated critical and should be addressed promptly.

Is the GMC C/K 2500 reliable?

The 1999-1999 GMC C/K 2500 has 3 known issues documented across 210+ owner reports. 3 issues are rated critical: In-Tank Fuel Pump Failure and 6.5L Diesel PMD/FSD Module Failure and Brake Line Corrosion and Rust-Through. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common GMC C/K 2500 problems?

Repair costs for known GMC C/K 2500 issues range from $250 to $2,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, In-Tank Fuel Pump Failure, typically costs $250-$700 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 1996-2000 GMC C/K 2500 In-Tank Fuel Pump Failure?

The C/K 2500's in-tank electric fuel pump fails without much warning, stranding drivers. The pump works harder in trucks used for towing and in hot climates. Running the tank below 1/4 accelerates wear since fuel cools the pump. Repairs typically run $250-$700. Severity: high.

What is the 1994-2000 GMC C/K 2500 6.5L Diesel PMD/FSD Module Failure?

Same 6.5L diesel injection pump PMD failure as Chevrolet C/K 2500. The Pump Mounted Driver overheats and causes stalling. Repairs typically run $300-$2,500. Severity: high.

What is the 1999-2003 GMC C/K 2500 Brake Line Corrosion and Rust-Through?

Same brake line corrosion issue as Chevrolet C/K 2500 and all GMT800 trucks. Steel brake lines corrode under securing clips on the frame rail, especially in salt-belt states. NHTSA investigated 6 million GMT800 trucks but no recall was issued. The lines can burst without warning,… Repairs typically run $400-$1,500. Severity: high.

1999 GMC C/K 2500 Problems: 3 Issues Every Owner Should Know

All 3 Known Issues

1996-2000 GMC C/K 2500: In-Tank Fuel Pump Failure#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

1994-2000 GMC C/K 2500: 6.5L Diesel PMD/FSD Module Failure#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

1999-2003 GMC C/K 2500: Brake Line Corrosion and Rust-Through#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

Other GMC Models

Frequently Asked Questions

What are the most common GMC C/K 2500 problems?

Is the GMC C/K 2500 reliable?

How much does it cost to fix common GMC C/K 2500 problems?

What is the 1996-2000 GMC C/K 2500 In-Tank Fuel Pump Failure?

What is the 1994-2000 GMC C/K 2500 6.5L Diesel PMD/FSD Module Failure?

What is the 1999-2003 GMC C/K 2500 Brake Line Corrosion and Rust-Through?