Fuel Pressure Fundamentals For 60 Series Detroit Engines

The fuel pressure of a Detroit Series 60 engine is a common topic of discussion among truckers and mechanics. The fuel pressure can vary depending on the engine speed, with some sources stating that the average fuel pressure should be around 30-35 psi. However, others have reported fuel pressures of 8-10 psi at idle and 25-30 psi at 1800 rpm. Troubleshooting low fuel pressure can involve checking the return flow, testing fuel pressure at the pump, and ensuring that the fuel lines are not mixed up or restricted. It is also important to verify that the fuel pump matches the engine serial number and that all connections and couplings are secure.

Troubleshooting high fuel pressure

To troubleshoot high fuel pressure on a 60 Series Detroit engine, follow these steps:

Step 1: Remove the Supply Fuel Temperature Sensor (SFT Sensor)

Remove the SFT Sensor fitting from the fuel pump. Refer to Figure "Supply Fuel Temperature Sensor" for the location of the SFT Sensor.

Step 2: Attach a Calibrated Gauge

Attach a calibrated gauge capable of reading 0-517 kPa (0-75 psi) or 0-345 kPa (0-50 psi) to the fuel pump.

Step 3: Start and Run the Engine

To avoid injury, ensure the vehicle is parked on a level surface with the parking brake set and wheels blocked. Also, always operate the engine in a well-ventilated area, as engine exhaust is toxic. Start and run the engine at the speeds listed in Table "Fuel Pressure (DDEC V with Regulator)" and record the fuel pressure. Then, shut down the engine.

Step 4: Remove the Calibrated Gauge and Reinstall the SFT Sensor

Remove the calibrated gauge from the fuel pump. Reinstall the SFT Sensor by referring to the Series 60 Service manual (6SE483 or 6SE2007), fuel system chapter.

Step 5: Analyze the Measured Fuel Pressure Readings

Analyze the fuel pressure readings you recorded. If the fuel pressure is within the specification listed in Table "Fuel Pressure (DDEC V with Regulator)", check for high fuel temperature return by referring to "12.5 High Fuel Temperature Return". If the fuel pressure is greater than the specifications, refer to "12.4.1 Combination Check Valve/Regulator Replacement" or "12.4.1 Fuel Pressure Regulator Replacement".

Step 6: Replace the Combination Check Valve/Regulator or Fuel Pressure Regulator

If you are replacing the combination check valve/regulator, refer to the appropriate service manual, fuel system chapter, for removal and installation instructions. Then, verify the replacement and test the engine to determine if the lack of power condition has been resolved.

If you are replacing the fuel pressure regulator, refer to the appropriate service manual, fuel system chapter, for removal and installation instructions. Then, verify the replacement and test the engine to determine if the lack of power condition has been resolved.

The impact of drilling out the restricted fitting

Drilling out the restricted fitting on the Detroit 60 series engine has been a topic of discussion and debate among mechanics and enthusiasts. Some people claim that drilling out the restricted fitting, which is located on the fuel-return-to-tank hose on the back of the head, can increase horsepower and improve fuel consumption. The theory is that by drilling out the hole to a larger diameter, more fuel is allowed to be injected, fooling the computer and resulting in a power boost of about 30 horsepower.

However, others argue that this modification may have negative consequences. One concern is that drilling out the restricted fitting will lower the fuel pressure, resulting in less fuel being delivered to the injectors, which could lead to reduced horsepower and torque. Additionally, it is believed that returning more hot fuel to the tanks at a faster rate will raise the fuel temperature, reducing the energy per gallon and impacting both power and fuel economy.

Some people have reported success with this modification, noticing a significant difference in performance. However, others have cautioned that it may only provide a temporary increase in power and could lead to long-term issues, such as lower fuel pressure and hotter fuel temperatures. It is also important to note that modifying the restricted fitting violates federal emissions regulations.

While drilling out the restricted fitting may provide a short-term power boost, it is essential to carefully consider the potential risks and implications before making any modifications to the fuel system. It is always advisable to consult with a certified mechanic or a Detroit Diesel specialist before proceeding with any changes to your engine.

The role of the return hose

The return hose on a Detroit 60 series engine plays a crucial role in the fuel system. The hose is responsible for returning excess fuel from the injection pump back to the fuel tank. This process helps regulate fuel pressure and ensure that the injectors receive the appropriate amount of fuel.

The return hose is connected to the back of the engine head, where there is a fuel restriction in place. This restriction is designed to maintain the necessary fuel pressure and provide the injectors with sufficient fuel. However, some people have suggested modifying the return hose by drilling out the restriction, claiming that it can increase horsepower without affecting fuel consumption.

However, others have argued that enlarging the restriction will result in lower fuel pressure and increased fuel temperature, which can lead to reduced power and fuel economy. Drilling out the restriction will allow more fuel to pass through the head, temporarily cooling the fuel but ultimately transferring more heat back into the fuel tanks. This can negatively impact fuel temperature and engine performance.

It is important to note that modifying the return hose in this manner may violate federal emissions regulations and is not recommended. The stock return hose configuration on the Detroit 60 series engine is designed to maintain optimal fuel pressure and temperature, ensuring the engine's performance and longevity.

The function of the calibrated gauge

The calibrated gauge should be capable of reading 0-345 kPa (0-50 psi) and is an essential tool for troubleshooting fuel pressure issues in the Detroit Series 60 engine. By measuring the fuel pressure, mechanics can identify if the fuel pressure is within specification or if it is greater than the specified limit. This information helps in diagnosing and resolving issues related to lack of power and poor fuel mileage.

In some cases, the calibrated gauge can also be used to measure fuel pressure at the fuel pump itself, providing valuable data for further analysis. Overall, the calibrated gauge plays a crucial role in maintaining and optimizing the performance of the Detroit Series 60 engine by providing accurate fuel pressure readings.

The importance of testing fuel pressure

Testing fuel pressure is a critical aspect of maintaining the health of your engine and ensuring optimal performance. By regularly testing the fuel pressure, you can identify issues early on and take corrective actions to prevent major problems down the line. Here are several reasons why testing fuel pressure is of utmost importance:

Preventing Engine Failure and Reducing Repair Costs:

Testing fuel pressure at regular intervals can help prevent catastrophic engine failure. Fuel contamination, for instance, can cause serious damage to fuel injectors and other engine components, leading to costly repairs. By regularly testing the fuel, you can identify potential issues and take necessary steps to maintain the integrity of your engine.

Ensuring Fuel Quality and Purity:

Fuel quality is paramount for the efficient operation of your engine. Contaminants in the fuel can lead to a multitude of issues, including clogged fuel injectors, increased component wear, reduced combustion efficiency, excessive engine smoking, and even the growth of bacteria, fungi, and mold. Regular fuel testing helps ensure that your fuel meets the required standards and specifications, reducing the likelihood of these issues.

Maximizing Power Output and Fuel Efficiency:

Impurities in the fuel can hinder its ability to burn efficiently, resulting in reduced power output and increased fuel consumption. By testing the fuel and maintaining its quality, you can maximize the power output of your engine and optimize fuel efficiency. This is especially crucial for diesel engines, which are designed with tighter clearances and operate under higher pressure.

Diagnosing Engine Performance Issues:

Testing fuel pressure is often the first step in diagnosing engine performance concerns. Low fuel pressure can lead to a slow startup, low performance, misfires, and stalling. On the other hand, high fuel pressure can cause excessive fuel consumption, black smoke from unburned gas, and rough idling. By testing the fuel pressure, you can narrow down the potential causes of these issues and make informed decisions about necessary repairs or adjustments.

Compliance with Regulations:

In certain cases, fuel testing is mandatory to comply with contractual obligations and EPA regulations. Regular fuel testing helps maintain documentation of the suitability of the fuel for use and ensures that your operations remain compliant with relevant standards and regulations.

In conclusion, testing fuel pressure is a critical aspect of maintaining your engine's performance and longevity. By regularly testing the fuel pressure and taking appropriate actions, you can prevent engine failures, reduce repair costs, maximize power output, and ensure compliance with relevant regulations.

Frequently asked questions