Fuel pressure regulator causing misfires?

What are the chances that a fuel pressure regulator can cause misfires. Also where is it located at?

 

Thank you for the response but my 2010 prius only has one hose at the top of the fuel assembly. I know other 3rd gen priuses have more than that. Yet there is two hoses running to the back, and the other hose seems to be running to the intake manifold. I already replaced the entire fuel assembly and it did not fix my problem (mainly because I dont think mine has 23280J in that location. I have checked both, spark plugs, coils, injectors and switched them all around with the others only to have the same problem keep occurring on the same cylinder. I also checked headgasket, bad piston O rings, and whole EGR. Coolant is same amount as always, oil same as well, and EGR cleaned and even blocked as a test, still misfiring. All I know is sparkplug from the faulty cylinder was dunked in fuel when I took it out and I have bad fuel smell. I believe it is running very rich in fuel, and my gas mileage is very poor. At highway speeds i dont experience any misfires. But any other time its just cylinder 1 and 2 being the main culprits, sometimes 3 or 4 rarely. This is very frustrating because it seems like I checked everything and i know its somewhere in the fuel system because I smell fuel everytime I drive and park the car. I get a fault code for that and my MAF being bad (despite cleaning it numerous times with MAF sprayer). I really really think it is the regulator. Just where is it on my prius, that is the question

Edit: also to show you pictures of what i mean. Left is mine, right is another 3rd gen prius. They might of adjusted the location for later year models due to situations like mine happening. And also, no regulator in my fuel assembly like the blueprint shows, just checked.

 

350k miles just about. I did not clean the EGR cooler because typically if only one of the cylinders were to be misfiring its due to one of the small ports in the intake being blocked, no? I put a sheet of metal inbetween the gasket right between the EGR cooler and the tube running to the intake manifold to block passage so I can test if that what was causing it, and no difference was made. I ruled the EGR out.

I also like to point out that my problem started when I tried to clean my cat by pouring paint thinner in the fuel tank (bad idea, but it did remove my cat check engine light at the cost of giving me misfires). Before that, i did not get any insane misfires like this. Which makes me believe its a problem with the fuel components somewhere. Like I said, theres no regulator in my fuel assembly that I replaced. All i can see inside the lower white bucket is the fuel pump and filter. Unless i am dumb and its part of it and I just dont know it yet. But that doesnt explain where the intake manifold hose leads to that follows to the fuel tank. I am planning to drop the entire fuel tank and figure out where the hose leads to. Maybe it will lead me to the pressure regulator hopefully.

I also noticed that its now mostly just cylinder 1 that misfires. Could it potentially be excess pressure in the fuel rail that all the fuel is being rammed to end of the last injector, this being cylinder 1?

 

My model has one hose connected to the fuel assembly. But there is another hose that runs along side it from the intake, and then it gets lost from view when it reaches the fuel tank. Id have to drop the entire tank to see where it leads to. So I suspect the pressure regulator would have to be tied to it because isnt that how it works? , correct me if im wrong.

Also typo, USA not USSA. I looked at all the diagrams and no luck finding mine. The fact that my fuel assembly is different and odd than what toyota diagrams show is a bit frustrating. I am surprised i ordered the right off brand part from China by sheer luck.

 

Well im glad you told me before i did that. I can try and take all the components out of the assembly and you can point out which might be the regulator. Is there any chance it might be in the front? I know gen 2 has it there i believe


Update: i guess you were right. It is there, but its a very small peice, much smaller than i thought, that i overlooked it.

I am going to try to check electrical connections but also my injectors one more time. Its just that one cylinder thats the problem now

 

What are the chances that the misfire can be caused by the wire harness for the fuel injectors? I retook the injectors out and re-arranged them in reverse, yet cylinder 1 keeps misfiring. It is hard to test because it isn't constant. So if you can imagine, the engine runs smooth for 5 seconds, then that one single piston starts misfiring, then back to normal, and so on and so forth. Very random if you ask me. What do you think this could be caused by?

 

No i have not, what are those and how do I check them? Also how do they relate to causing a misfire, just to educate myself.

I dont have the proper tool to check compression (hopefully I do not have a bent valve or anything inside the piston) but I did check the fuel and sparks. I have not checked for any vacuum leaks either.

There is something odd that is happening. When I have the vehicle in park and press the gas+brakes, it gives me cylinder 2 misfiring on my OBD2. But when I shift to drive, it is typically cylinder 1. Sometimes its both, but mostly 1 when I am driving at a regular speed and not idling. Now when I shift to neutral, all the noises go away and engine works without misfires. I suspect this is due to the transmission not force spinning the crankshaft.

I am not sure what the correlation from park to drive is yet that make cause different pistons to misfire, but that might get me closer to my problem.

My problems are only piston 1 & 2. Never 3 & 4. Or at least that is what the computer tells me. And also, they are never consistent, but frequent. I lose a lot of gas mileage to this as well.

 

Update: As i was trying to clean out my pcv valve thinking that couldve been part the issue, i notice a bunch of oil leaking from the back side of the engine what looks like its coming from the headgasket and other areas. It looks like it ran down and these wires are coated in oil. One of them runs to the O2 sensor but i am unsure of the other ones. They seem to head up the engine which must mean theyre part of the spark plug wiring harness maybe?

 

Thanks, and I already looked at the EGR. I've cleaned it twice now.

Update: I ended up taking all the spark plugs out again and coils. This time i tested the ohms on the coil and found something interesting. They all have similar resistance except cylinder #2 which i never checked for and its at 14 while the rest are at 12. Could this potentially been the source of my problem? I had not yet switched that one around but i would like to clean or replace first

 

Like so, not sure exactly the path its taking, but if its different it must mean it could potentially be a problem