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GMC · Known Issues

1999 GMC C/K 2500 Problems: 3 Known Issues

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

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Issue summary

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 with published estimates, repair costs range from $250 to $2,500. DIY maintenance guides at au7o.io.

In This Article

  • C/K 2500 Engine2
  • C/K 2500 Brakes1
  • FAQ
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In This Article

  • Engine2
  • Brakes1
  • FAQ

All 3 Known Issues

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ALL YEARS20032002200120001999199819971996199519941993199219911990
Community reported
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.

Typical repair cost:$250 - $700

Research This Issue

Based on 210 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High Confidence210 owner 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.

This issue also affects: Chevrolet C/K 2500

Common Symptoms

  • Stalling while driving
  • No start when hot
  • Hard starting

How to Fix

Typical repair cost:$300 - $2,500

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
Medium Confidence

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.

Typical repair cost:$400 - $1,500

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
Medium Confidence
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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 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 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.

Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

Data sourced from 210+ owner reports, NHTSA recalls, TSBs, and automotive forums.