Fuel in oil

Hi,

On this vehicle, the system is a mechanical return less fuel system (MRFS). The fuel pressure regulator, in this case, is in the fuel tank and part of the fuel pump module.

Here is the definition from the manual:

The fuel pump (FP) module contains the fuel pump, the fuel pressure regulator, and the fuel sender assembly. The fuel pressure regulator is attached to the FP module and regulates the pressure of the fuel supplied to the fuel injectors. The fuel pressure regulator controls the pressure of the clean fuel as the fuel returns from the fuel filter. The fuel pressure regulator is a diaphragm-operated relief valve. Fuel pressure is established by a spring preload applied to the diaphragm. The FP module is located in the fuel tank.

As far as the fuel issue, do you have a live data scan tool? If you do, I need you to check two things. First, check the short-term fuel trims. Also, when the engine is cold, check the coolant temperature sensor signal. It should be the same or very close to the ambient temperature. If it is on the extreme end of "cold", that could be causing the computer to run an extremely rich fuel mixture.

Let me know if this helps and if you can perform the test.

Take care,

Joe

Hi,

There really isn't. Interestingly, as long as the computer is receiving a signal from the temperature sensor, it doesn't know if it is right or wrong. It just knows the sensor is telling it a temperature.

The fuel trim info I asked for was to help as well. If the computer is adding fuel, I would be able to tell.

Let me ask you a question. Have you checked the fuel pressure at the engine? That will provide us with knowing if it is a pressure regulation issue. All you need is a fuel pressure gauge. Most parts stores will lend one to you. Here is a link that shows in general how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

The attached pic shows the manufacturer's specifications are for pressure. The port should be on the fuel rail itself.

Since the engine has 200,000 on it, there is a chance that you even have an injector leaking down when you turn the key off. With that many miles, the fuel wouldn't have too much trouble getting past the piston/rings and into the oil. It's just a theory at this point.

Let me know.

Joe

Sounds good. When you perform the pressure test, watch fuel pressure drop off when the key is turned off. It should hold pressure for some time before slowly dropping off about 10 psi. If it drops fast, then we will need to check the injectors.

Take care,

Joe