Logging Fuel Pressure: 1G Dsm Stock Guide

The stock fuel pressure on a 1G DSM varies depending on the model and whether the vacuum hose is connected or disconnected. For a 1G manual with the hose disconnected, the stock fuel pressure is 37 psi, while for a 1G automatic and N/T, it is 43 psi. With the vacuum hose connected, the stock fuel pressure for a 1G manual is 27 psi, and for a 1G automatic and N/T, it is 33 psi. It is important to note that the base fuel pressure is always set with the reference port vacuum line disconnected and plugged to avoid any vacuum leaks. Additionally, the fuel pressure regulator must be connected to the vacuum line to ensure that the fuel pressure rises with boost psi 1:1.

Stock fuel pressure

The stock fuel pressure on a 1G DSM (1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4) varies depending on the specific model and transmission type.

1G Non-Turbo (Manual or Automatic)

For the 1G non-turbo models, the stock fuel pressure is 47.6 psi with the vacuum line disconnected and 38 psi with the vacuum line connected.

1G Turbo Manual

The stock fuel pressure for the 1G turbo manual is 36.3 psi or 37 psi with the vacuum line disconnected and 27 psi with the vacuum line connected.

1G Turbo Automatic

For the 1G turbo automatic, the stock fuel pressure is reported as either 41-46 psi or 43 psi with the vacuum line disconnected and 33 psi with the vacuum line connected.

2G Models

Although this request focuses on 1G models, it is worth noting that the stock fuel pressure for 2G turbo models is 42-45 psi with the vacuum line disconnected and 33 psi with the vacuum line connected.

Fuel Pressure Testing

It is important to note that base fuel pressure is typically tested with the engine running and the vacuum line disconnected and plugged to prevent vacuum leaks.

Fuel pressure with vacuum line on/off

The fuel pressure regulator maintains the pressure of fuel delivered to the injectors at a constant level. The stock fuel pressure on a 1G DSM is 37 psi with the vacuum hose off and 27 psi with it on. The vacuum line is connected to the regulator to make this happen. Since at idle, the engine is in a vacuum, the regulator lowers fuel pressure while the line is connected.

The vacuum line from the fuel pressure regulator (FPR) should be connected to the solenoid on the firewall. This allows the PCM to override fuel pressure settings under wide-open throttle. The PCM can compensate for the extra fuel pressure.

If you are running a base fuel pressure of 50 psi, you will run 64 psi at 14 psi boost. The vacuum in the intake doesn't directly change the fuel pressure, but it does impact the fuel delivery rate of the injectors. It is the difference in pressure between the inlet and outlet that creates the flow through the injector.

The base fuel pressure is tested without the vacuum line attached to the FPR. This is done to prevent vacuum leaks.

Fuel pressure regulator

The fuel pressure regulator (FPR) is a critical component of a car's fuel system, ensuring the injectors receive a constant fuel pressure and maintaining the correct balance of air and fuel. The FPR adjusts fuel pressure by the exact amount of pressure in the manifold, so if there is 10 psi of boost in the manifold, the regulator will increase fuel pressure by 10 psi. This 1:1 ratio is essential to keeping the actual fuel pressure constant and ensuring the injectors deliver the same amount of fuel over time.

For example, let's say the fuel rail has 10 psi of boost and 43 psi of fuel pressure, totalling 53 psi. When the fuel injector opens, the 10 psi of boost will create resistance, meaning only 33 psi of total fuel pressure is achieved. However, if you increase the fuel pressure to 53 psi, the injectors will still experience that 10 psi of resistance from the boost, but the total fuel pressure will now be 43 psi as desired.

The FPR also plays a role in fuel delivery rate. As boost increases, fuel pressure rises at a 1:1 ratio, which slows down the rate at which the pump moves fuel and affects the delivery rate of the injectors. Therefore, the FPR helps to maintain the correct balance of air and fuel.

When it comes to the 1G DSM, the stock fuel pressure with the vacuum hose off is 37 psi for a manual and 43 psi for an automatic and non-turbo model. The STM 1G DSM Fuel Pressure Regulator Kit is a popular choice for those looking to upgrade their fuel system. It includes all the necessary fittings, hardware, and lines for a bolt-in installation.

Fuel injectors

First, it's important to determine the correct fuel injector size for your vehicle. For the 1G DSM, the stock fuel injectors are typically 450cc, as mentioned by a user in a forum. However, it's always a good idea to refer to the vehicle's specifications or consult a professional to ensure you have the correct information for your specific car.

Next, fuel injector problems can sometimes occur, causing issues with the vehicle's performance. In the case of the 1G DSM, some owners have reported experiencing problems with their fuel injectors. For example, in a forum post, a user mentions that two of their fuel injectors are not working properly, leading them to seek replacements. It's important to address any issues with fuel injectors promptly to avoid further complications.

When it comes to replacing or upgrading fuel injectors, there are several options available for the 1G DSM. Several brands offer fuel injectors specifically designed for this vehicle, including Deatschwerks, Injector Dynamics, Fuel Injector Clinic (FIC), and Precision Turbo & Engine (PTE). These injectors come in various sizes, such as 750cc, 850cc, 1000cc, and 1200cc, allowing you to choose the appropriate option for your needs. It's always recommended to consult a professional or a trusted mechanic when making modifications to your fuel system to ensure compatibility and proper installation.

Additionally, when working with fuel injectors, it's crucial to consider the fuel pressure regulator and the associated vacuum hose. As discussed in the forums, the fuel pressure and vacuum settings can impact the performance of the fuel injectors. Adjustments to the vacuum hose and fuel pressure regulator can affect the base fuel pressure, which is an important factor in ensuring the fuel injectors function correctly. Therefore, it's essential to have a good understanding of the fuel system as a whole when making any modifications or replacements.

Fuel pump

The fuel pump is a critical component of a car's fuel system, responsible for supplying fuel from the tank to the engine. When discussing how to log fuel pressure for a 1G DSM, it's important to understand the role of the fuel pump and the options available.

The stock fuel pump for a 1G DSM, such as the Mitsubishi Eclipse, Eagle Talon, or Plymouth Laser, typically delivers fuel at a pressure of around 37 psi. This pressure is measured with the vacuum hose disconnected from the fuel pressure regulator. However, it's worth noting that some sources suggest that the stock fuel pressure for a 1G DSM could be as low as 335 kPa (47.6 psi) for non-turbo models or 255 kPa (36.3 psi) for turbo models.

If you're experiencing issues with your fuel pump or looking to upgrade, there are several aftermarket options available. High-performance fuel pumps, such as the Walbro 255 LPH or the DeatschWerks DW300 320 LPH, can provide increased fuel flow and pressure, which is beneficial for modified engines or those running on alternative fuels like E85. These fuel pumps are available as direct replacements for the stock unit and often include installation kits.

When replacing or upgrading the fuel pump, it's essential to consider the fuel pressure regulator and the overall fuel system. Ensuring that the fuel pressure is correctly regulated helps maintain the desired fuel flow and pressure, optimizing engine performance and fuel efficiency. Additionally, a functional regulator prevents fuel pressure from dropping too low, which can lead to engine stalling, or rising too high, potentially causing damage to fuel injectors.

In conclusion, understanding the fuel pump's role and maintaining optimal fuel pressure are crucial aspects of keeping your 1G DSM running smoothly. Regularly checking and, if necessary, adjusting the fuel pressure can help ensure reliable engine performance and prolong the life of critical components.

Frequently asked questions