The Yamaha GP800, a high-performance personal watercraft (PWC) from the late 90s and early 2000s, offered exhilarating speed and handling that made it a favorite among enthusiasts. However, like any machine, the GP800 wasn't without its quirks and potential problems. Understanding these issues can help owners maintain their watercraft, prevent costly repairs, and keep enjoying the thrill of riding.

So, What's the Deal with the GP800?

The GP800 was renowned for its powerful 785cc two-stroke engine, delivering impressive acceleration and top speeds. Its relatively lightweight hull made it agile and responsive, perfect for carving through the waves. But that power and performance came with a price – a need for diligent maintenance and a susceptibility to certain common issues. This article dives deep into those problems, offering insights and potential solutions to keep your GP800 running smoothly.

Common GP800 Issues: Let's Break It Down

Here's a rundown of the most frequently encountered problems with the Yamaha GP800, along with potential causes and fixes:

1. Engine Problems: The Heart of the Matter

  • Overheating: This is a prevalent issue, especially in warmer climates or when riding aggressively. The GP800's cooling system can struggle to keep up under high loads.

    • Causes:
      • Clogged Cooling Lines: Saltwater and debris can accumulate in the cooling lines, restricting water flow.
      • Faulty Thermostat: A malfunctioning thermostat can prevent the engine from cooling properly.
      • Damaged Impeller: The impeller that draws water into the cooling system can be damaged by debris.
      • Air Locks: Air trapped in the cooling system can hinder its efficiency.
    • Solutions:
      • Flush the Cooling System: Regularly flush the cooling system with fresh water to remove salt and debris. Consider using a cooling system cleaner.
      • Replace the Thermostat: A new thermostat is relatively inexpensive and can resolve overheating issues.
      • Inspect and Repair/Replace the Impeller: Check the impeller for damage and replace it if necessary.
      • Bleed the Cooling System: Follow the manufacturer's instructions to bleed any air from the system.

  • Carburetor Issues: The GP800 uses carburetors to deliver fuel to the engine, and these can be sensitive to fuel quality and age.

    • Causes:
      • Clogged Jets: Small jets in the carburetors can become clogged with fuel residue.
      • Sticking Floats: The floats can stick, causing fuel to flood the engine.
      • Air Leaks: Air leaks in the intake system can disrupt the air/fuel mixture.
      • Old Fuel: Stale or contaminated fuel can cause poor performance and carburetor problems.
    • Solutions:
      • Clean the Carburetors: Regularly clean the carburetors to remove any buildup. You might need to disassemble them for a thorough cleaning.
      • Replace Fuel Lines: Old fuel lines can crack and leak, leading to air leaks.
      • Use Fresh Fuel: Always use fresh, high-quality fuel and consider using a fuel stabilizer.
      • Adjust Carburetor Settings: If the air/fuel mixture is incorrect, you may need to adjust the carburetor settings. Consult the service manual for proper procedures.

  • Crankshaft Problems: A more serious issue, crankshaft problems can lead to major engine damage.

    • Causes:
      • Lack of Lubrication: Insufficient oil can cause the crankshaft bearings to fail.
      • Over-revving: Exceeding the engine's maximum RPM can put excessive stress on the crankshaft.
      • Detonation: Detonation (pinging) can damage the crankshaft and other engine components.
    • Solutions:
      • Use High-Quality Oil: Always use the recommended oil for your GP800 and ensure proper oil injection.
      • Avoid Over-revving: Pay attention to the engine's RPM and avoid exceeding the maximum limit.
      • Address Detonation: If you suspect detonation, check the fuel quality, ignition timing, and carburetor settings.

2. Electrical Gremlins: The Unseen Enemy

  • Battery Issues: A weak or dead battery can prevent the GP800 from starting.

    • Causes:
      • Old Battery: Batteries have a limited lifespan and will eventually need to be replaced.
      • Loose Connections: Loose battery connections can prevent the battery from charging properly.
      • Faulty Charging System: The charging system may not be charging the battery correctly.
      • Parasitic Drain: Something may be drawing power from the battery even when the GP800 is not in use.
    • Solutions:
      • Test the Battery: Have the battery tested to determine its condition.
      • Clean and Tighten Connections: Clean and tighten all battery connections.
      • Check the Charging System: Use a multimeter to check the charging system's output.
      • Identify and Eliminate Parasitic Drains: Use a multimeter to track down any parasitic drains.

  • Ignition Problems: Issues with the ignition system can prevent the engine from starting or running properly.

    • Causes:
      • Faulty Spark Plugs: Worn or fouled spark plugs can prevent the engine from firing.
      • Faulty Ignition Coil: The ignition coil may not be producing enough spark.
      • Faulty Stator: The stator generates the electricity needed for the ignition system.
      • Faulty CDI Unit: The CDI unit controls the timing of the spark.
    • Solutions:
      • Replace Spark Plugs: Replace the spark plugs regularly.
      • Test the Ignition Coil: Use a multimeter to test the ignition coil.
      • Test the Stator: Use a multimeter to test the stator.
      • Test the CDI Unit: Testing the CDI unit often requires specialized equipment.

3. Jet Pump Woes: Power to the Water

  • Impeller Damage: The impeller is responsible for creating thrust, and damage to the impeller can significantly reduce performance.

    • Causes:
      • Ingestion of Debris: Rocks, seaweed, and other debris can damage the impeller.
      • Cavitation: Running the GP800 in shallow water can cause cavitation, which can erode the impeller.
    • Solutions:
      • Inspect the Impeller: Regularly inspect the impeller for damage.
      • Repair or Replace the Impeller: Minor damage can sometimes be repaired, but severe damage will require replacement.
      • Avoid Running in Shallow Water: Avoid running the GP800 in shallow water to prevent cavitation.

  • Wear Ring Problems: The wear ring surrounds the impeller and helps to create a tight seal, maximizing thrust.

    • Causes:
      • Wear and Tear: The wear ring will eventually wear out over time.
      • Ingestion of Debris: Debris can damage the wear ring.
    • Solutions:
      • Inspect the Wear Ring: Regularly inspect the wear ring for wear and damage.
      • Replace the Wear Ring: Replace the wear ring when it becomes worn or damaged.

4. Hull and Steering Issues: Staying Afloat and in Control

  • Hull Damage: Cracks or holes in the hull can lead to leaks and affect handling.

    • Causes:
      • Impacts: Collisions with other objects can damage the hull.
      • Stress Cracks: Stress cracks can develop over time, especially in areas that are subjected to high stress.
    • Solutions:
      • Inspect the Hull: Regularly inspect the hull for damage.
      • Repair Hull Damage: Minor damage can often be repaired with fiberglass or epoxy. Major damage may require professional repair.

  • Steering Cable Problems: A damaged or corroded steering cable can make it difficult to steer the GP800.

    • Causes:
      • Corrosion: Saltwater can corrode the steering cable.
      • Wear and Tear: The steering cable can wear out over time.
    • Solutions:
      • Inspect the Steering Cable: Regularly inspect the steering cable for corrosion and damage.
      • Lubricate the Steering Cable: Lubricate the steering cable regularly to prevent corrosion.
      • Replace the Steering Cable: Replace the steering cable when it becomes corroded or damaged.

Prevention is Key: Keeping Your GP800 Happy

While issues can arise, proactive maintenance is crucial for extending the life and reliability of your GP800:

  • Regular Flushing: Flush the engine and cooling system with fresh water after each ride, especially in saltwater.
  • Fuel Stabilizer: Use a fuel stabilizer when storing the GP800 for extended periods.
  • Proper Lubrication: Use the recommended oil and ensure proper oil injection.
  • Regular Inspections: Regularly inspect all components for wear and damage.
  • Service Manual: Consult the service manual for proper maintenance procedures and specifications.

Frequently Asked Questions (FAQ)

  • Why does my GP800 keep overheating? Clogged cooling lines, a faulty thermostat, or a damaged impeller are common culprits. Flush the system, check the thermostat, and inspect the impeller.
  • My GP800 is hard to start. What could be the problem? A weak battery, faulty spark plugs, or carburetor issues are common causes. Test the battery, replace the spark plugs, and clean the carburetors.
  • How often should I flush the cooling system? After every ride, especially in saltwater, to prevent corrosion and buildup.
  • What type of oil should I use in my GP800? Always use the oil type recommended in your owner's manual.
  • Where can I find parts for my GP800? Many online retailers and local PWC shops sell parts for the GP800.

The Thrill is Worth the Effort

The Yamaha GP800 remains a sought-after PWC for its performance and exhilarating ride. While it's prone to certain issues, understanding these problems and implementing preventative maintenance can ensure years of enjoyment on the water. Regular care will help you avoid major repairs and keep your GP800 running at its peak.