Fuel pressure problem

Hey. I have a problem with my toyota losing fuel pressure after sitting for 10 hours or more. No need for a gauge, cause when I loosen the front banjo bolt on the fuel rail there is no gas. And they do hold pressure for quite a while. Cause I have several more in the yard and they can sit for a month without starting and I can crack that same bolt and fuel squirts out. So my first thought was check valve in the fuel pump. Replaced that and no , that wasn't it. I laid in under the truck as it was running and can't see any leaks. As I replaced the fuel filter about a couple weeks earlier so I thought that I may have had a leak there, but no. So I've read about fuel injectors getting stuck and leaking. And I got new refurbished injectors and that didn't fix it. And had old ones tested for a leak. I've taken the plenum off and put a jumper in and turned the key on to see if I had a leak on the rail on all the injectors and anywhere else on top of the motor, and no leaks I can see. My oil don't smell like gas so I'm pretty sure it's not an injector. And I've replaced the fuel pump with one new one and tried two used good ones.So I'm saying it's not in the fuel pump. There has to be a leak somewhere. Cause the fuel will drain back down out of the fuel rail. So where in the world could it be? The motor is a 3.0 . But as far as I can see the fuel system is the same as the 3.4. Other than a fuel pressure regulator( which I replaced) and the fuel pulsating damper on the back of the rail. But anyway there pretty much alike. ( Don't get technically anal) I know the injectors are a little different in spec) . What I'm saying that if someone has ran into this issue on a 3.4 it could be the same fix as a 3.0. So if anybody knows of some magical check valve that is hiding somewhere other than the fuel pump, or if there is some way a gas tank that isn't sealed completely would cause it( highly unlikely ) or any crazy reason, then please do share. I'm not a asc certified mechanic, but I have rebuilt a few of these motors and replaced cliches and transmissions and everything else on these trucks and 4runners ,so I know my way around them pretty good. That said, I sure don't know everything.

 

When you had the fuel pump out did you check the pressure line on the fuel pump bracket for cracks .

How does the Truck run??

Take forever to start

what year 3.0 are you working on??

Did some of them still have the pump prime with ignition switch on??

 

I replaced that little rubber pressure line and even used good clamps on it. I thought that also. And I looked at the metal line also.Truck runs fine after it starts. And yes it takes about 8 to 10 seconds of cranking before it starts. But that's because it doesn't have any fuel in the fuel rail at first. Which is the whole problem it takes a while to get fuel to start. It's a 94 3.0. Which I have 3 of them but I haven't had one any earlier than a 91. And all of them that I have do not prime when the key is in the on position. I don't know about any earlier than a 91. But this is a 94 and it the same. I can put in a jumper wire and turn the key to on and let it build up for about 10 sec. And it will crank right up. I'm sure I have a fuel leak somewhere, I just don't know where? But since I have an easy access to the fuel pump then I'll pull the pump bracket back out and put that line under air pressure and see if I can find a leak even though I looked at it real good. That would be the only place where it could leak and spray fuel and me not be able to see it. I'll do that tonight when I get home and let you know if I missed it before.

 

Quite possible you got a bad injector in the batch.

Unless your nose is really weak an external gas leak should be easy to smell

Comes down to draining back into the tank or going into the engine

Evap Hoses all hooked up correct it can happen to the best of us.

Good Luck

 

If the fuel rail drains there is a leak, somewhere. It appears you know the parts of the system so you must have missed something or replaced a bad with a bad. You could pinch/plug the fuel return line to eliminate the FPR. Don't start/run it like that.
The 3.4 fuel system in good shape should hold enough pressure to run/sputter for a second or two after 24 hrs without the fuel pump operating.

 

Yeah I agree, if there is fuel in the fuel rail and not leaking back. I had replaced the fuel injectors and had the old ones tested for leaks, so either they lied to me about testing the old ones and I have a bad new one or it's not an injector. And I can't smell gas in the oil. And there should be quite a bit if that was the problem. And I did pinch off the FPR on the return side and the sending side at different times and that didn't make a difference. The only thing I can think of is that I have a crack that I couldn't see in the metal sending line
on the pump hanger. I'm going to check that again tonight.

 

Well, just got through pulling the fuel pump and looking at the metal line it connects to and the small rubber line and put air pressure in them and unfortunately no leak there. So I went ahead and pinched off the sending line up by the motor where it's rubber and I'll see what it does in the morning. My bet is that I'll have fuel pressure and it will start right up. So if it does then the only thing I know to do is to just replace the whole line all the way to the pump. But if it don't then the only thing I know would be a bad new injector. If I wasn't trying to sale it , I wouldn't worry about it. But since I'm trying to get rid of it, I don't want someone buying a bunch of unnecessary parts to try to remedy this hick-up.