Checking Fuel Pressure: 1999 C1500 Suburban Guide

If you're experiencing issues with your 1999 Chevrolet C1500 Suburban, it could be down to low fuel pressure. A fuel pressure test gauge can be connected to the fuel system to determine whether the fuel pump is faulty. This can be done by connecting the gauge to the Schrader valve located on the fuel injector rail. If the fuel pressure is within the specification, the pump is working correctly. However, if the pressure is 0 psi, it indicates a defective pump. Alternatively, if the pressure is below the indicated specification, the pump is failing and needs to be replaced.

Symptoms of a bad fuel pump

A fuel pump is located inside your fuel tank and has a small electric motor to ensure that pressurised gasoline flows to the engine to power the vehicle. A fuel pump will generally fail in one of two ways. Firstly, it will either stop working completely, producing no fuel pressure and causing the engine not to start. Secondly, the fuel pump will begin to fail and function only enough to start the vehicle, but the engine will not run optimally.

• The engine cranks but does not start.
• The engine starts but stalls after a few seconds.
• The engine starts but as soon as you step on the accelerator pedal, the engine stalls.
• Lack of power while driving the vehicle.
• Explosions can be heard coming from the intake manifold when you step on the accelerator while the engine is under load.
• The check engine light is on, and lean air fuel mixture trouble codes are stored in the fuel injection computer's memory.
• The engine "chokes" or struggles to maintain speed.
• Noises, backfires, and a sputtering engine.
• Hesitation at start or take-off.
• A bad fuel pump can overheat, causing the engine to overheat.
• A whirring sound coming from your fuel tank, as fuel pumps do not normally make noise.

Testing the fuel pressure with a gauge

Once you have your fuel pressure test gauge kit, follow these steps:

Step 1: Connect the Fuel Pressure Tester

Locate the Schrader valve on the fuel injector rail, which is on the passenger side of the intake manifold. Connect your fuel pressure tester to this valve.

Step 2: Crank the Engine

Have an assistant crank the engine while you observe the needle on the fuel pressure tester gauge.

Step 3: Observe the Reading

The fuel pressure tester should give you a reading between 55 to 62 PSI for the 1999 C1500 Suburban.

Step 4: Interpret the Results

There are three possible cases to interpret your test results:

Case 1: If the fuel pressure is within the specified range of 55 to 62 PSI, your fuel pump is functioning correctly.

Case 2: If you get a reading of 0 PSI, it indicates that the fuel pump is defective, which is why the engine is not starting. Before replacing the fuel pump, ensure that the fuel pump relay and fuse are supplying power to the fuel pump when cranking the engine.

Case 3: If the fuel pressure is below the specified range, it means that the fuel pump is supplying fuel but not enough for the engine to run optimally. In this case, the fuel pump is failing and needs to be replaced.

By following these steps and interpreting the results, you can effectively test the fuel pressure in your 1999 C1500 Suburban using a fuel pressure gauge.

Using starting fluid to diagnose a no-start condition

To diagnose a no-start condition, you can use starting fluid (also known as ether) or carb cleaner. This can be done by spraying the fluid into the throttle body bore or any vacuum line on the intake manifold.

It is important to note that ether is very volatile and can be dangerous. It should be avoided for general automotive use. One person reported that a lot porter at a dealership used ether to start cars on cold mornings and created several problems, including an explosion in the intake manifold and washing down cylinder walls, causing a no-start due to low compression. Therefore, aerosol carb cleaner is recommended as a safer alternative.

To perform the test, follow these steps:

• Remove the rubber hose from the intake.
• Manually open the butterfly.
• Spray a small amount of carb cleaner inside (just a couple of seconds worth).
• Put the hose back on.
• Start the engine.

If the engine runs for a few seconds with the carb cleaner, it indicates that there may be a problem with the fuel system, such as a failed pump. However, it is not a definitive test, as there could be an electrical fault causing the injectors to not pulse. Therefore, further diagnostics may be necessary to identify the exact cause of the no-start condition.

Buying a fuel pressure test gauge

A fuel pressure test gauge is an important tool for any DIY enthusiast to have in their toolbox. It can be used to diagnose issues with your fuel pump, which may be faulty if your engine is cranking but not starting, stalling after a few seconds, or lacking power while driving.

You can buy a fuel pressure test gauge from a variety of places, including online retailers like Amazon and AutoZone, as well as your local auto parts store. When purchasing a fuel pressure test gauge, there are a few things to consider to ensure you get the right product for your needs.

First, check that the gauge can be connected to your vehicle's fuel system. Most fuel pressure test gauges will connect to the Schrader valve located on the fuel injector rail, usually on the passenger side of the intake manifold. Ensure your vehicle has this valve or that you can purchase an adapter if needed.

Second, consider the pressure range that the gauge can measure. Most gauges will measure from 0-100 or 0-140 PSI, which is suitable for testing most fuel systems.

Third, look at the features of the gauge. Some gauges have easy-to-read displays, brass fittings, and pressure relief valves for safe and clean testing. You may also want to consider purchasing a kit that includes adapters and additional tools for a more comprehensive solution.

• Actron CP7838 Professional Fuel Pressure Tester
• OEMTOOLS 27167 Fuel Pressure Test Kit
• Performance Tool W89726 Master Fuel Injection Test Kit
• BETOOLL 0-140PSI Fuel Injector Injection Pump Pressure Tester Gauge Kit
• TU-114 Auto Fuel Pressure Gauge Tester Kit
• Orion Motor Tech Fuel Pressure Gauge Test Kit

Interpreting test results

There are several ways to interpret the results of a fuel pressure test on a 1999 C1500 Suburban. One way is to use a fuel pressure test gauge to measure the fuel pressure in the fuel system. The fuel pressure specification for the 1999 C1500 Suburban with a 4.8L, 5.3L, or 6.0L engine is 55 to 62 PSI. Flex fuel engines should have a pressure of 48-54 PSI. If the fuel pressure is within this range, it indicates that the fuel pump is functioning correctly.

If the fuel pressure is below the specified range, it indicates that the fuel pump is not supplying enough fuel to the engine, and it needs to be replaced. In this case, the engine may exhibit symptoms such as lack of power, stalling, or a check engine light illuminated with lean air-fuel mixture trouble codes.

Another way to interpret the test results is to swap out the fuel pump relay with another relay, such as the AC relay. If the fuel pressure test gauge records 56-62 PSI after swapping the relay, it confirms that the original fuel pump relay is defective and needs to be replaced. If the gauge records 0 PSI, it could mean that the fuel pump relay is not the issue, but further testing is needed to be sure.

Additionally, it is important to ensure that the fuel pump relay and fuse are supplying power to the fuel pump when cranking the engine. If battery power is available to the fuel pump during cranking, but the fuel pressure is still below the specified range, it confirms that the fuel pump is defective and needs to be replaced.

It is also worth noting that a bad fuel pump can sometimes deliver enough fuel to keep the engine running but not enough to start the engine. In this case, spraying starting fluid or carb spray into the intake may help the engine start, but it is not a reliable solution as the fuel pump will likely need to be replaced soon.

Frequently asked questions