Engine cranks but does not start, codes P0170 and P0172

Hi,

I looked at the code definitions. The P0172 indicates a lean mixture and the P0170 indicates the fuel trims are outside the range of specification set by the manufacturer.

If you hear the pump, it doesn't mean it's good. Also, it's possible that the fuel filter is clogged.

I need you to try something. See if the engine starts for a couple of seconds using starting fluid. If it does, then we know it is a fuel-related issue. At that point, I need you to check the fuel pressure.

The fuel filter, which could be clogged, is an integral component of the fuel pump assembly. So, if pressure is low, we will need to remove the pump. See pic below

Let me know if it starts with starting fluid.

Take care,

Joe

See pic below.

Hi,

Make sure you check for spark at the spark plugs. Using starting fluid should have made a difference if it was fuel related. However, the idea that you have lean fuel mixtures and no fuel in the line tells me either the pump is bad, there is a restriction, or a filter is clogged.

Here is a link that explains how to check for an ignition spark:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Let me know.

Take care,

Joe

Hi,

Although you hear the fuel pump turn on, it likely has failed. Even if you had a partially plugged fuel filter, you would see some fuel.

At this point, I would suggest replacing the pump. Please note that I am suggesting this based on the idea you hear it turn on. If it didn't, it could be a fuse, a relay, or a wiring issue. Also, since you had a lean fuel mixture code, the pump was likely going bad for some time.

If you look below, I attached the directions for replacing the pump. The fuel tank does not need to be removed. Open the trunk and remove the floor (removable). Once that is out, you will see an access port for the fuel pump that can be removed to replace it.

Additionally, here is a link you may find helpful. It explains in general how one is replaced.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

I think this is the issue. Let me know if I can help in any way. Also, let me know if this takes care of the issue.

Take care,

Joe

See pics below.

Hi,

Do you have fuel in both the supply and return? If that is the case, there must be fuel at the fuel rail (Schrader valve) you check. If there isn't pressure and the lines have fuel, it makes no sense.

Is it possible for you to take a pic of where you are checking for fuel and upload it for me to see?

Thanks,

Joe

Hi,

You're correct. That is the damper. This isn't making sense. How could the fuel travel through the supply line and then through the return at the pump and not go through the damper?

I'm a bit perplexed. I would like to try something, but it requires you to be very careful. If you loosen the damper to release pressure and cover it with a dry rag, cycle the key on and then off quickly to see if the rag gets wet with fuel. Also, disconnect the regulator when you do this.

Note that fuel should shoot from the component, so make sure it is securely covered with a rag and only cycle the key very quickly.

Let me know if you get fuel.

Joe

The regulator wouldn't stop the fuel, so that's why I'm confused. It can certainly cause other issues. I actually suggested removing the vacuum hose to the regulator because I was wondering if there was fuel in it. That would indicate a faulty diaphragm and it could pump fuel through the vacuum hose into the intake.

Let me know. If there is no fuel at the damper, I am going to see if one of the other techs has any ideas.

Take care,

Joe

Hi,

It could be the regulator itself. It could be drawing fuel directly through the vacuum hose. Are you able to get a small pair of pliers in there to gently twist the vacuum hose so it breaks loose and can be removed?

Let me know.

Joe

Hi,

That will need to be replaced. When you did get it off, was there any evidence of fuel in the hose?

Let me know.

Joe

Hi,

Yes, that does appear correct. Do me a favor. Allow the engine to idle and remove that hose and confirm there is a vacuum present.

Let me know.

Joe

Hi,

With 300,000 on the engine, it could be compression. However, that usually starts slowly and not all at once.

Regardless, it doesn't hurt to test. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-test-engine-compression

Let me know what you find. I'm interested in knowing.

Joe