Regan Brown
If you're having trouble with your TBI 350 fuel injectors, you're not alone. Many people have reported issues with their Chevy TBI motors not firing up due to problems with the injectors. In this article, we will provide a step-by-step guide on how to remove and replace your TBI 350 fuel injectors, as well as offer some tips and tricks for troubleshooting common issues. We will also discuss the importance of regular maintenance and share some resources for further education on the topic. By the end of this article, you should feel confident in your ability to tackle any issues that may arise with your TBI 350 fuel injectors.
How to Remove Fuel Injectors on TBI 350
| Characteristics | Values |
|---|---|
| Engine | 350 |
| Vehicle | Chevy Blazer, Chevy K2500, Chevy S10, Chevy Impala SS, Chevy Caprice, Isuzu, Buick Century |
| Year | 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994 |
| Fuel injector issues | Fuel not being sprayed, fuel not reaching throttle body, fuel in injectors but not being dispensed while cranking the starter |
| Possible causes | Clog, pinched line, plugged filter, bad ignition module, bad computer, bad ground, faulty fuel pump, faulty fuel pressure regulator |
| Troubleshooting steps | Check resistance between injector connectors, check signal from distributor magnetic pickup, check voltage at the injector, ground the injectors at the ECM, check oil level and oil sensor, check fuel pump fuse and relay |
| Repair/replacement options | Clean and service injectors, replace injectors, rebuild TBI, replace fuel pump, replace fuel pressure regulator |
| Tools required | Flat-head screwdriver, large screwdriver, test light |
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What You'll Learn
Troubleshooting a non-firing TBI 350
Check for Vacuum Leaks:
Vacuum leaks are a common issue with TBI systems, and they can lead to high idle and unstable engine performance. Inspect the intake gasket and ensure there are no leaks, especially if you're using an aftermarket carb intake.
Inspect the Spark Plugs:
Examine the number 3 and number 4 spark plug electrodes. If the coloring on these plugs doesn't match, it could indicate a faulty injector or a faulty chip. Blackened plugs suggest that there is too much fuel in the system.
Fuel Delivery to the Injectors:
Ensure that fuel is reaching the injectors. If the injectors are not dispensing fuel, it could be due to a clog, a pinched line, or a plugged filter. Check for any restrictions in the fuel lines and confirm that the fuel filter is clean and functioning properly.
Injector Operation:
Verify that the injectors are functioning correctly. If the injectors are not firing when cranking, it could be due to an issue with the ignition module or the ECM (Engine Control Module). Check the wiring and fuses associated with the injectors to ensure they are receiving power.
Check the Check Engine Light:
Observe the behavior of the check engine light. If it blinks once and then stays on when the key is turned to the "on" position, it could indicate an issue with the ignition module or the ECM.
Fuel Pressure:
Ensure that the fuel pressure is within the specified range. Low fuel pressure can prevent the injectors from functioning properly. Check the fuel pressure gauge and ensure it reads within the acceptable parameters for your specific vehicle.
Throttle Position Sensor (TPS):
A faulty TPS can cause issues with engine performance and fuel delivery. Replace the TPS if necessary, and ensure that the new sensor is properly calibrated and installed.
Fuel Injector Cleaning and Replacement:
If the injectors are clogged or faulty, consider sending them to a reputable fuel injector cleaning and reconditioning service. You can also choose to replace the injectors with compatible ones, ensuring that you select the correct injectors for your vehicle.
Distributor and Ignition Components:
Check the distributor and related components, such as the cap, rotor, and ignition module. Replace these parts if necessary, especially if they are showing signs of wear or damage.
Engine Performance Chips:
If you have made modifications to the engine, such as a cam change, ensure that you are using a chip designed for your specific camshaft. Using an incorrect chip can lead to incorrect fuel delivery and unstable engine performance.
Knock Sensors:
Use the correct knock sensor for your vehicle's year and model. Later model TBI systems use a different knock sensor that looks identical to the older ones but will cause performance issues if used interchangeably.
Fuel Pressure Regulator:
Consider replacing the fuel pressure regulator when swapping injectors. A faulty regulator can affect fuel delivery and engine performance.
Remember to refer to service manuals and seek professional assistance if you are unsure about any repair procedures. Safety should always be a top priority when working on automotive systems.
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Cleaning and reconditioning injectors
Step 1: Procure Used Injectors
Before sending your injectors for cleaning or reconditioning, you have the option to acquire used injectors. This can be a cost-effective solution, as you can find used TBI units at junkyards or auto salvage yards. However, it's important to ensure that the used injectors are compatible with your vehicle.
Step 2: Choose a Reputable Cleaning/Reconditioning Service
Once you have the injectors, the next step is to find a reputable fuel injector cleaning and reconditioning service provider. There are specialized businesses that offer these services, and you can research their reputation and pricing. Some providers offer mail-in services, while others may require you to bring your vehicle to their location.
Step 3: Send Injectors for Cleaning and Testing
Whether you choose a mail-in service or a local mechanic, sending your injectors for professional cleaning and flow testing is essential. This process ensures that any built-up debris or blockages are removed, improving the performance and longevity of your injectors.
Step 4: Install Reconditioned Injectors
After your injectors have been professionally cleaned and tested, it's time to install them back into your vehicle. Make sure to follow the correct installation procedures and torque specifications to ensure a proper seal and avoid any leaks.
Additional Considerations:
- It is recommended to service your injectors regularly and not wait until there are noticeable issues.
- Some people choose to service their injectors at home using an ultrasonic cleaner and a flush machine. However, this requires specialized knowledge and equipment.
- Be cautious when using off-the-shelf cleaners, as they can break up particles that may end up blocking your injectors.
- Consider using fuel additives, such as Techron Complete Fuel System Cleaner, to maintain your injectors and fuel system between services.
By following these steps and considerations, you can effectively clean and recondition your TBI 350 injectors, ensuring optimal engine performance and longevity.
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Using a flat-head screwdriver for leverage
To remove the fuel injectors from a TBI 350, you will need to take off the top plate that sits on top of the injectors. This can be done by removing the eight screws that hold it in place. Once the top plate is removed, you can use a flat-head screwdriver to gently pry and leverage the top cover loose.
Place the flat-head screwdriver under the lip of the injector and gently apply force to pop the injector out. This will require some force, but be careful not to damage any other components. It is recommended to put something between the screwdriver and the top cover to gain more leverage.
The process of removing the injector is made easier by the presence of a lip around the very top of the injector. This lip provides a convenient surface to apply upward pressure with the screwdriver, allowing the injector to be dislodged with a gentle pop.
Using a flat-head screwdriver in this manner is an effective method for removing the injector without causing damage to the surrounding components. It provides the necessary force to dislodge the injector while also allowing for precise control and maneuverability in the tight space of the engine.
By following these steps and utilizing the flat-head screwdriver for leverage, you can successfully remove the fuel injectors from a TBI 350.
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Replacing the fuel pressure regulator
When replacing the fuel pressure regulator, there are a few options to consider. Firstly, you can choose to rebuild the existing regulator or replace it entirely. Rebuild kits are available, and they typically include a new diaphragm and sometimes a spring. It is important to note that the shop manual advises against disassembling the fuel pressure regulator due to the risk of leakage when reassembling it.
If you decide to rebuild the regulator, you will need to purchase a suitable kit. The Standard Auto rebuild kit, which includes the spring and diaphragm, is a popular choice and is reasonably priced at $26. Another option is the Delphi kit, which features a nitrile diaphragm that is more resistant to ethanol but does not include the spring. This kit is priced at $68.
When rebuilding the regulator, be aware that some kits come with extra screws that may seem like they don't belong. These screws are temporarily used to position the fuel pressure diaphragm correctly before being replaced with regular screws. Once reassembled, turn the key on and check for any leaks, as improper sealing can lead to fuel leaks or dribbles.
Alternatively, you can choose to replace the fuel pressure regulator entirely. This option is recommended by the shop manual to avoid potential issues with reassembling the regulator. When replacing the regulator, ensure that you select a suitable replacement that is compatible with your vehicle's specifications.
Additionally, consider the benefits of an adjustable fuel pressure regulator. While a stock regulator may be sufficient for a standard engine, modifications to your TBI unit may require a regulator that can be fine-tuned to prevent the engine from running rich or lean. This can be achieved by modifying the stock regulator or using an external regulator.
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Testing for a bad ignition module
One way to test for a bad ignition module is to check the ignition wire to the coil for 12 volts. If there is no voltage, a jumper can be run from a 12-volt source to the coil to see if it fires. If the engine has an external coil, it is possible to test for spark by disconnecting the coil wire and holding a spark tester near the coil while someone tries to start the engine. If there is no spark, the ignition module or the coil could be faulty.
Another way to test the ignition module is to Ohm the pickup coil and compare the results to the specifications. This can be done using an ohmmeter. Additionally, some auto parts stores have the equipment to test the ignition module.
It is also important to check for any trouble codes that may provide insights into the issue. Furthermore, the bypass wire can be tested if the engine is running to see if the ignition timing is advancing.
In some cases, the ignition module may need to be replaced with a known good one to determine if it is the cause of the issue. This trial-and-error method can help narrow down the problem, especially if other potential causes have been ruled out.
It is worth noting that ignition modules can fail intermittently before completely failing, so a thorough diagnosis is recommended before spending time and money on replacements.
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Frequently asked questions
To remove the fuel injectors on a TBI 350, first, take the top plate off the top of the injectors (8 screws) and then take a flat-head screwdriver and put something between it and the top for leverage. The injector has a lip around the very top, so put the screwdriver under the lip and pop the injector out.
There could be a number of reasons for this. Firstly, check if there is fuel pressure at the injector. A clog, pinched line, or plugged filter could be causing the issue. You should also check the ignition module, as this controls the ECM firing the injectors.
Some common issues with TBI 350 fuel injectors include a lack of fuel being sprayed, incorrect fuel pressure, and issues with the ignition module or computer.
