1999 Corolla Fuel Pressure Regulator Replacement. Need Help. - Toyota Corolla, Chevy Prizm (1998-2008)

Bad_dude

Hi guys,

Working to get rid of the P0171 code. So far, no vacuum or exhaust leak. Replaced the upstream O2 sensor. The code is still there. The mechanic says for sure it's the fuel pressure regulator. I need some help on a video or some sort of good instructions to see if I could do it myself. The mechanic wants $350 to do the job and guaranteed the code will go away. I wonder if I could do it myself to save some money.

Thanks.

Pressure regulator is on the fuel pump assembly - have to dig it out of the tank. Lot of work, but should be doable for a home DIYer. I remember seeing a write on this forum or TN on how to get at it, but don't don't have the link handy.

Pretty hard to believe it is a bad pressure regulator, as I haven't heard of any of those on a 8th gen going bad. Did the mechanic measure fuel pressure to come to that conclusion or was he shooting from the hip on that diagnosis, since you've ruled out many other possibilities?

Bad_dude

I don't think he had the time to do fuel pressure test. He just guess it. Where do you suggest I start from here? If the fuel pressure regulator is bad, would the car has problem accelerating or poor idling? The car runs well other than the CEL being on for P0171.

Thanks.

You would definitely be having drivability issues if the FPR is bad. Plugs might get fouled easily as well. Can't be sure without doing a pressure test of the system - $350 is a hell of a gamble. That he said he'd guarantee it - that is sort of odd to me.

I'd blame injectors and O2 sensor before I'd pick on the FPR, especially with this model year.

Bad_dude

Well I replaced the front O2 sensor with a Denso, so it's not that. I guess what remains is the injectors. How do I test those? Could a code scanner pick this one up?

Thanks.

Only if the injectors completely failed. Injectors could be clogged or solenoid is gummed up, causing their overall spray pattern to be less than optimal. Unfortunately, hard to test them without pulling them and putting them through a bench test. You can listen to the tell-tale clicking noise when they actuate, and pull the plugs to see how well they are working. But aside from that - hard to tell if they are good or not, almost have to swap those out and see if the symptoms change.

Bad_dude

Is it easy to replace the injectors? Is there a write up or some thing? Or a video?

Thanks.

Pretty easy - lots of videos online, probably a write up or two on this forum alone. Lots of times, in the process of checking out the injectors - most find that the injectors might still be OK, its the o-rings that are dry rotted and cracked. But you can't see that until you pop the injectors out.