AgRunner06

Can someone with a 3.0 pleeeeaaaasssseeee do me a quick favor. I'd like you to get your engine up to operating temperature and then pull the vacuum advance hose on the fuel pressure regulator off and then drive it. I just want to see what the results are. I did it to mine and it made no difference in how the motor ran. However I suspect my fuel pressure regulator might have issues.

Please...it'll only take a minute.

Thanks

Bumpin' Yota

the FPR is the doohicky sitting atop the driver's side front end of the fuel rail correct? And the line you are describing is the line going to the top of this doohicky?

miket223

Pulling that hose will do nothing except kill your gas mileage. That hose applies manifold pressure to the fuel pressure regulator. At idle it reduces the fuel pressure, at WOT it applies full fuel pressure. It won't give you any gains.

AgRunner06

Yes that's correct. Doohicky...that's one of those technical terms isn't it?

So you are saying that pulling it will have no effect on how the engine runs? If so, then crap I'm back to square one.

dragon564

Okay Ag for you.......and it took more than a couple of minutes.......

I warmed it up and disconnected the top vac line and plugged it drove around the runway and noticed no difference. the bottom hose goes to the fuel tank return so I did not run with that off. So I came back to the office and picked up one of my Japanese co worker that once worked for Toyota. Off to Sagamihara Toyota we went. Once there His buddie took the truck out back and did some test on the FPR which the say is working although it was somehow disconnected. (that was me) So now for the questions....
How come I did not noticed that it was disconnected?
It is a vac assit spring system the spring does most of the work any way.
HUH?
When you push down the accel vac increases and the valve will close the return line, however so will the fuel pressure that is building up anyway the vac just helps do it faster.
So what happens when I stop pushing the accel?
Vac decreases and so does fuel pressure and the valve opens more allowing built up or unused fuel to flow back to the tank.
So I can take the vac off the FPR and never know it?
yes. but you should not (of course a toyota factory mech is going to say that)
So how do I know if the FPR is bad?
two tests same spot
Warm up engine then disconnect the fuel return and hold with white paper and idle to 2000 RPM 1 minute then back to normal 1 minute then off. No fuel spots on paper FPR is full closed and broken. If paper is so much wet, hand is to wet FPR is open and broken. Should just be some spots or little wet.
But truck will run with broken FPR?
yes but not good (again he had to say that)
What can happen if FPR broken?
If open? not too good power no fuel for engine
If closed? too much fuel maybe break injector
but no worry FPR not break too much.


You will have to forgive me the translation but he was hyped up to talk to an American......He want to learn good speak english......

I do not think that that helps you out, but then again you have not described your problem either.....

AgRunner06

Thank you very much. I really appreciate you going through all that trouble for me. I will definitely follow what he said to test my FPR.

AgRunner06

Ok I waited until the 4runner was hot, unplugged my FPR, and started it up. It gushed fuel so I shut it off immediately. I think even if I ran it at 2K and back to idle there would still be massive amounts of fuel coming out of the fuel return line.

Does this sound like it's bad? It does to me. If I had had a piece of paper in front of it, it would have been soaked in no time.

My 4runner is running lean and I have a hesitation only at a certain temperature that I haven't been able to figure out and I've tried everything. I think this may be the problem.

What do you guys think?

dragon564

Based on that it sounds to me as if the FPR has gone bad. Just so you know we pulled the FPR hoses on my buddies runner and ran it like the guy at toyota said....it was the same as mine...so I would think that your FPR has gone out.....just to check .....run down to half tank of gas.....pull the gas cap and blow some air down the return line.....just to make sure the return line is not plugged.....

AgRunner06

I replaced the FPR with a used one I had bought a while back. It seems to run smoother but I haven't been able to check if it will still hesitate.

Thanks again for your help.