The Nissan Patrol GQ TB42 with its carburetor (carby) engine is a rugged 4×4 classic, known for its reliability and off-road capability Nissan Patrol GQ TB42 Carby. However, like all vehicles, it’s not immune to issues that can affect its performance. If you’re experiencing problems with your GQ TB42 carby, this guide outlines some of the most common issues and provides potential fixes to get your Patrol back in top condition.
1. Hard Starting or Stalling
One of the most common complaints from GQ Patrol owners is difficulty starting the engine or stalling after the vehicle is warmed up. This can be caused by several factors:
Causes:
- Fuel delivery issues: The carburetor may not be delivering fuel properly to the engine, often due to clogged jets, a dirty fuel filter, or a failing fuel pump.
- Carburetor misadjustment: If the idle mixture or idle speed screw is out of adjustment, it can cause poor idling or stalling.
- Vacuum leaks: Leaks in hoses or seals can affect air-fuel mixture balance, leading to poor engine performance.
Fixes:
- Inspect and clean the carburetor: A thorough cleaning of the carburetor can resolve clogging or buildup of dirt and gunk in the jets.
- Check the fuel filter and pump: Replace the fuel filter and ensure the pump is working efficiently.
- Adjust the carburetor: Refer to the manual for the proper idle mixture and idle speed adjustments.
- Inspect vacuum hoses: Replace any cracked or disconnected hoses, and check for leaks around the carburetor gasket.
2. Fuel Smell and Poor Fuel Economy
If your Patrol starts to emit an unusually strong fuel smell or you notice a significant drop in fuel economy, this could indicate an issue with the carburetor’s fuel mixture or an overflow issue.
Causes:
- Rich fuel mixture: If the carburetor is supplying too much fuel to the engine, it can lead to increased fuel consumption and an unpleasant odor.
- Fuel leaks: Carburetor seals, fuel lines, or the fuel bowl could be leaking, allowing fuel to escape.
Fixes:
- Adjust the carburetor: If the carburetor is running rich, you’ll need to adjust the air-fuel mixture screws to lean it out.
- Check for leaks: Inspect the carburetor and fuel lines for any signs of leaks, and replace seals or lines as needed.
- Replace the needle and seat: If fuel is spilling from the carburetor, the needle and seat might be worn or dirty. Replacing them should help.
3. Rough Idling or Hesitation on Acceleration
If you notice that your Patrol idles roughly or hesitates when you press the accelerator, there are a few common culprits that could be causing the issue.
Causes:
- Dirty carburetor jets: The jets in the carburetor can become clogged over time, preventing a smooth flow of fuel.
- Ignition system issues: Worn spark plugs or faulty ignition timing can lead to hesitation.
- Air-fuel mixture imbalance: If the carburetor is improperly adjusted or there’s a vacuum leak, the air-fuel mixture can be too lean or too rich.
Fixes:
- Clean the carburetor jets: Remove and clean the jets with carb cleaner to ensure proper fuel flow.
- Check the ignition system: Inspect the spark plugs and ignition timing, replacing plugs or adjusting the timing as needed.
- Adjust air-fuel mixture: Fine-tune the carburetor’s idle mixture and speed screws.
4. Backfiring or Poping Through the Carburetor
Backfiring or popping sounds from the carburetor are a clear sign that something is wrong, and it’s usually related to the fuel or ignition systems.
Causes:
- Lean air-fuel mixture: If the carburetor is running too lean, it can cause misfires or backfires.
- Ignition timing issues: Incorrect timing can result in backfiring or popping, especially when accelerating.
Fixes:
- Adjust the carburetor: Ensure the air-fuel mixture is balanced and not too lean.
- Check ignition timing: Verify that the timing is set according to manufacturer specifications and adjust if necessary.
5. Poor Acceleration or Lack of Power
A common issue for owners of the GQ Patrol TB42 carby is poor acceleration, especially when driving at higher speeds or going uphill.
Causes:
- Clogged air filter: A dirty air filter can restrict airflow to the engine, leading to reduced power.
- Carburetor or choke problems: If the carburetor or choke is malfunctioning, the engine might not be getting the right amount of fuel and air.
Fixes:
- Replace the air filter: A clean air filter can improve airflow and engine performance.
- Check the choke operation: Ensure the choke is working properly and not sticking in the closed position, which can cause poor acceleration.
6. Engine Surging
If your Patrol experiences surging (accelerating and decelerating on its own), this is often a sign that the carburetor is malfunctioning.
Causes:
- Sticking throttle or choke: A sticky throttle or choke can cause fluctuations in engine speed.
- Carburetor flooding: If the carburetor is overflowing or if there’s an issue with the float, it can result in surging.
Fixes:
- Lubricate throttle and choke linkage: Ensure all moving parts are free of dirt and properly lubricated.
- Inspect the carburetor float: If the carburetor is flooding, check the float and needle valve to ensure they’re functioning correctly.
Final Thoughts
The Nissan Patrol GQ TB42 carby, with its solid design, remains a favorite among off-road enthusiasts. While carburetor issues can seem daunting, most problems can be solved with a bit of patience and some basic mechanical knowledge. By addressing the common problems outlined in this guide—cleaning the carburetor, adjusting fuel mixtures, and ensuring proper ignition—you can keep your Patrol running smoothly for years to come. If you’re not comfortable performing these fixes yourself, consider taking your vehicle to a mechanic who specializes in carbureted engines.
