Mine has started cranking 95% of the time since I put the higher octane in it, but still reporting poor mileage. The car is running great, if this is a fuel pump replacement issue, it seems really weird since it works so well most of the time.

 

Read post #8, and post #10 - they explain what is likely happening there with your HHR.

What was the result of testing it with a fuel pressure gauge?

 

I need to check the fuel pressure still, work keeps me too busy to do these things right away.

What should the fuel pressure be for the 2.4?

 

You gotta get used to using the SEARCH tool at the top of the page, especially if you need info quickly.

Ok, using the SEARCH tool, 50-60psi seems to be the numbers you need to see.

 

Thanks, thats what I thought. I had found something saying that they thought it was 50-60 when I used the search function, I was just looking for confirmation.

 

What post #8 explains is the valve in the pump holds the fuel in the lines so it's right there at the engine when you turn your key.
If the valve (in the pump) fails then while the car is off the fuel drains out of the lines back into the tank leaving nothing at the ready when you crank it. This means that when you go to start the car, the fuel pump has to work and pump fuel through the lines to the engine (where it should have been hanging out just waiting for you to fire the HHR again ) and that creates the extended cranking times and the lag in the engine actually firing.

The "pump" portion of the F/P assembly may still be just fine and that's why it will still run great once it gets started.

If your losing the pressure in your lines then when the computer does the evap test it's going to notice the leak and pop a code.

If I'm not mistaken , when you check the fuel rail for pressure you'll only get a quick burst of it with the key off, your basically relieving the stored pressure it keeps to fire up quickly, if you test it with the key in the on position, but engine not running, you should keep that 50-60psi.

I'm not a mechanic so someone please correct that last sentence if I'm wrong. I have done a few F/P diag and repairs and this is just what I've found to be true on other vehicles.

 

Yup - you got it right!!! Without that residual pressure being present with the key off, it generally means the fuel pump will need to re-fill/repressurize it when the engine is started - which can result in a no-start on first starting the car as it needs refilling.

 

Except that the EVAP monitor tests the tank vapor pressure not the fuel pressure. The weight of the fuel in the tank prevents the "leak" from showing up.

Did I make that understandable?

 

Thanks for the clarification

 

Several things will cause a code P0171. Low fuel pressure. If you turn the key to on but not start the pump will only run for a few seconds. Use a pressure gauge to see if the system holds pressure of 58lbs. If not, pump may be leaking back into the tank, leak in line or leaky fuel injector.

Use a non-contact thermometer to shoot each header. A cooler header would indicate a non-working or clogged injector. Use a NOID light to test the injector for proper operation.

Last is to look at the short term and long term fuel trims. Need a scanner able to look/rec ord this info. This is what actually sets the P0171 code and can tell a troubleshooter lots.

New cars require new tools OR befriend a neighborhood mechanic.