Fuel pressure problem?

Hello all,

I have a 1998 tacoma 2.7l 3rz reg cab 4x4 auto. In the last 6 months I've had to replace my head, as well as all the parts associated with the job. It sat for approximately 6 months during this endeavor. In doing so, I had my injectors cleaned, replaced my fuel filter, fuel pressure regulator, and throttle position sensor, cleaned my intake manifold and intake runner.

Since then, whether hot or cold, it starts very quickly. But, if I don't time it just right and it doesn't start, it takes longer than normal to start, like as if it's not getting enough fuel.

Now, I'm getting the code P0171 air/fuel mixture system lean bank 1. I've been researching all the problems associated with this. I've been thinking that I need to test the fuel pressure.

I'm wondering if maybe the Beck/Arnley fuel pressure regulator I installed may be the problem or the fuel pump might've stopped working properly. I was gonna start with testing the fuel pressure, but then I started thinking it might be the fuel pressure regulator.

Does anyone possibly have any insight on this? Thanks in advance!

 

You need to know your fuel trims. Find a data reader. P0171 is triggered by two more trips where total fuel trim meets or exceeds 30, if I am not mistaken; that suggests a vacuum leak causing your fuel system to compensate.

I have a URD fuel rail adapter if you want it. I’ll mail it to you for cheap. At idle with the vacuum line disconnected from the regulator, pressure should be approx 42-45 psi. On, it should be around 35 psi. Obviously, a stable pressure is ideal. Variance is just as important as pressure.

If that doesn’t solve your problem then find a smoke machine and look for leaks. That’s always hard so good luck.

 

P.S. Go through my post history. I recently went through a similar experience. Maybe you will glean something from those posts.

 

You just had the intake off, check for vacuum leaks

And check fuel pressure

 

Now that you mention it, I also replaced most of my vacuum lines with silicone hose. I will check for leaks, but I highly doubt that's the problem.

I don't know what the fuel rail adapter is, but I'll look into it and let you know if I'm interested. I'll also go through your posts and see what I can figure out. Thanks!

 

Yes, I had the whole top-end off and replaced every gasket associated with the rebuild.

My next step was to check fuel pressure, but that seems like an ordeal. Any recommendations on how to do it myself?

 

You'll need a pressure test kit - gauge, hoses, adapters

It would be nice to know what the fuel trims are at idle vs under load

 

It’s essentially what the other user mentioned. What I am offering is what he referred to.

The fuel rail adapter goes where your fuel pressure regulator attaches. If you notice, there is nowhere for you to measure the pressure. That’s where the adapter comes into play. You need a mechanical gauge. There’s plenty on Amazon. Just make sure you get one with glycerin (to suppress vibration, corrupting the pressure reading) and made by a reputable brand like Aeromotive or Turbosmart.