spitfiremkiii

Hi all
My wife was driving the 94 4 runner 22RE (220k miles) over some very rough twisty roads when the engine died. Previous to this everything was fine. The truck will now idle poorly with a definite miss. (no backfire) Lacks power. The truck will run, then it will lack power and chug then its fine. I essentially tuned the engine and tried to eliminate as much as I could ( the gory details follow) to identify the problem. What I have found is zero pressure in the fuel lines. When I inserted a fuel pressure gauge in either fuel line at the union of the flexible hoses and steel lines just in front of the gas tank I got zero pressure on both line with the engine running! What am I missing? I checked the fuel pressure regulator and it seems to work.

Here is what I've done
New spark-plug wires, distributer cap and rotor arm.
Reset the timing and adjusted the idle to spec.
Cleaned and gapped the plugs (Look like new, little carbon on them and tan in colour). Checked the ignition coil impedance both primary and secondary, all within spec. Checked each plug was getting a good spark. Two methods one crank the engine with the plugs out and grounded and with the plugs in and used the inductive trigger on my timing light on each wire.
Checked the compression in each cylinder all good ~180 psi
Since the tappets were clicking a little I removed the valve cover and everything looked good, no broken valve springs etc. (Kind of redundant since the compression test was good)
Acoustic check of injectors, all clicked regularly.
Removed the fuel pressure regulator (FPR) and tested it opens around 45 psi with a compressed air line and that the diaphragm operates with vacuum.
Checked the vacuum control valve controlling the FPR worked.
I can hear fuel flowing with ignition on
Inserted a fuel pressure gauge in what I though was the supply line from the fuel pump at the rubber hose from the gas tank to the steal fuel lines. No pressure with the engine running or when shorting the terminals in the diagnostic connector. Thinking I had the wrong line I switched the gauge to the other line and still no pressure. I can hear the pump run.

So is this a bad fuel pump and or pressure regulator or controlling circuit to the regulator?

Your help is greatly appreciated.

Bako88

Can you take the return line off the regulator and clamp an extra long fuel line and visually check the fuel flow and maybe use the gauge there? I used this trick to see if I had a restricted return line. Not sure if it will help. If you hear fuel flowing, I don't see how it could be the fuel system.

You might take off the large intake tubing from the AFM to the Throttle Body and check for cracks or openings. This has caused people a lot of headaches.

Hope you find your answer soon.

spitfiremkiii

You are right Bako88 with fuel flowing and the regulator seeming to check out, the testing is pointing to the controlling circuit. I ran out of time to trouble shoot the problem and so dropped the truck off at the CarMax/Toyota dealer yesterday. They diagnosed a bad AFM. They replaced it for ~$800, ouch, and about one hour of labor. Truck runs beautifully more crisper acceleration, I guess they AFM was on its last legs for the last month or so. There is a silver lining, I finally had the steering relay rod replaced as part of the recall!

Thanks.