Where is the fuel pressure regulator and fuel pressure test port on a 2000 Toyota Corolla?

I'm trying to test the fuel pressure b/c I'm getting a check engine light with DTC PO171. Before having the O2 sensor(s) replaced, I'm trying to do everything I can on my own to find out the issue. I've already cleaned the mass air flow sensor and want to check my fuel pressure next to see if I should look into the fuel pump or fuel filter. I have a scantool, so I can perform some tests through the OBDII connector if there is a way to isolate the issue this way. Any help will be much appreciated! Thanks.


At idle, my long term fuel trim is at 10.2%. I cleaned the MAF using CRC QD Electronic cleaner twice. The second time, I actually removed the MAF from the air filter compartment so I could get a better angle at the contacts and the car ran much better, but PO171 is still coming up after driving approx. 30 miles.

Update 2:

I forgot to mention that when I was getting LTFT at 10.2%, I had already cleared the error code. It came back again (it usually comes back around 30-40 miles driving highway), and it says the LTFT was 30% when the CEL went on. I'm going to replace the MAF sensor, now that I only have to spend $$ on hardware (I can do the labor)! Still can't find the danged fuel pressure test port. I think I'll go to the library to find a service manual...

1 Answer

  • 1 decade ago
    Favorite Answer

    Don't replace your o2 sensors just yet--they are spendy. They have had issues with the Hot wire type air flow sensors getting oil residue and sometimes even debris as small as a spider web can cause a lean code. Also, when you clean it care must be taken not to use carb spray or anything that will leave a residue( we use brake cleaner as it has a drying agent and usually won't leave cleaning residue). Even after cleaning it may need replacing. If your scan tool can check the data list- you want to check the long Fuel Trim as this is what the computer is watching when it sets a lean code(Usually around 30%). Depending on the rpm- you want to see no more than 10-15% long fuel trim. Good Luck--T&T(ADDED: 10% at idle is too high...there is no demand, so it should be minimal; around 1%-there is either still an issue w the airflow meter, or your injectors are restricted- i would start w a new meter{known problem}-clear the codes,unplug efi fuse for 5 mins to reset trim-then drive-see if it comes back)

    Source(s): MDT tech for Toyota
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