Originally Posted by EricA
I connected the pump to the fuel line and I break the fuel line before the fuel rail and regulator. Then I forced the pump on using ODBII software. The fuel flows out of the line going into the regulator fine. However, if I reconnect the line, run the pump for a bit and then disconnect the fuel line again there seems to be nothing pressurized. Fuel doesn't even drip out.
With all the other troubleshooting you did, what you wrote above gets my attention. Comments:
-- It seems like your fuel system parts work okay when there is no "back pressure." "Back pressure" is the pressure on the pump discharge due to restrictions yada in the pipes downstream of the pump. When you re-connect everything, the back pressure goes up and something gets thrown off. I am thinking a pressure regulator is not working right. Pressure regulators typically have little diaphragms in them that can weaken with time or develop a hole.
-- The fuel pressure regulator in the tank (a part of the fuel pump module assembly) is Toyota part number 23020-28010. Google on the part number, and photos of the regulator will come up. The in-tank fuel pressure regulator re-circulates part of the fuel pump discharge. If the regulator is not working correctly, or is erratic, then I think it might give the symptoms above. The regulator seems to rarely fail. Still, I might try installing a used in-tank fuel pressure regulator from a salvage yard.
-- I would consider replacing whatever "fuel pressure regulator" you found at the fuel rail. I cannot find a Toyota part number for this. I cannot find a diagram showing this. I am not sure there is a fuel pressure regulator outside the fuel tank. Is there a part number stamped on the one you found?
-- I think there is a fuel pressure sensor at the rail. I see reports of it setting off code p0191 on OBD2 vehicles, including Rav4.2s. Maybe check this as well.
-- Watch for O-rings. My Rav4.1's in tank fuel pressure regulator involves a few. If the O-rings are worn, then the fuel system may not be holding pressure.
-- If you can post photos pointing to the pulsation damper, fuel rail and "fuel pressure regulator"(which you say is outside the fuel tank), this might be helpful. I am not having much luck finding a good fuel system diagram for the Rav4.2.
Less likely causes of the no fuel situation:
-- There is a second fuel filter. It is a part of the 'fuel pump module assembly' that you have removed from the fuel tank and re-installed several times now. Google for toyota part number 23300-28040 (formerly, 23300-28030), and you will see photos of this second filter. It is typically called the "fuel filter assembly" and similar. This filter is not shown well at U. S. Toyota parts site diagrams. This site has a superior exploded view of the fuel pump module, showing way more detail: http://www.jp-carparts.com/toyota/pa...ype=7&fig=7701
. (For the 1996-2000 Rav4, U. S. part sites are similarly terrible when it comes to a similar, secondary fuel filter located in the fuel tank. I think the point is, Toyota feels one should 'ordinarily' never have to replace these secondary fuel filters. But extraordinary conditions do arise on our old Ravs. I found my Rav4.1 secondary filter filthy, due to a rusty fuel tank.) This second fuel filter is currently about $26 plus s/h at McGeorge toyota parts. McGeorge confirms this second filter is used on the generation 2 Ravs. EBay has this filter as well. For what it is worth, my 2003 Honda Civic had a similar setup: One fuel filter (strainer) at the pump suction, and a second fuel filter assembly at the discharge or in the recirc line, both in the fuel tank.
-- Have you ever changed out the entire fuel pump module assembly with one from a salvage yard? This would include the fuel pump, in-tank fuel pressure regulator, suction filter (a.k.a. strainer or sock), and the secondary fuel filter assembly, all built into the fuel pump module assembly?
-- For the interested reader, an aftermarket part number for the entire fuel pump module that leads to helpful photos on the net is Spectra SP9038M .
-- Dunno about OBD2 and the cycling on and off of the pump. I tend to think the cycling points to something that is broken.