Hello, so I'm currently having a lean situation. Code 41 R and a code 12(idle out of range). I've looked into leaking vacuum lines, no issues, passed the smoke test to rule out possible intake manifold leak. No condensation on the oil cap, no air bubbles in the reservoir tank when engine Is warm. I recently replaced the O2 sensor upstream and still having issues. Now I recently did a fuel pressure check, I got a 35 psi when the Haynes Manuel specifies that psi should be at 40 engine off(priming) and running. Fuel pump is new, no more than a year old. Filter was replaced as well during the same time. Symptoms: starts but stalls immediately, it's usually the 3 to 4 attempt that it stays on, at which point the idle is about 700 to 800 Rpms. Fuel pressure at engine running is 35 psi, when I removed the vacuum like from fuel regulator it's psi goes up to 40 psi. When I'm activating the throttle the psi drops slowly but not hearing any hesitation, it's when I open a full throttle the paid drops to 20 psi, doesn't stalls out but kinda does want to. I'm leading to suspect it's a failing fuel pump, but I'm also suspecting a may have a bad fuel injector. I'm gonna be testing them soon. What are the ohmn reading for the imjector?(i dont recall seeing itinn the haynes manual). I'll also be checkling the ignition coil to rule out a bad electrical current at start up(recently did cap and rotor, cables will be doing plugs today), though it wouldnt explain why their be a lean condition, right? It a 1992 Ford ranger 2.9 4x4 drive....it just hit the 300k mile mark. Thank you for your time.

 

Ford fuel injectors run 11 to 18ohms
Run a can of Seafoam or similar injector cleaner in the gas tank, that will clean injector tips

Pull off fuel pressure regulators vacuum hose and plug hose with a bolt/screw, its OK to run the system this way
See if stumbling goes away on start up

1988 to 1992 2.9l should NOT have an EGR Valve, yours doesn't right?

IAC(idle air control) Valve can be cleaned, computer uses it to set idle and code 12 would point to a problem there, and if its stuck it can also cause Lean code
Cold engine should REV to 1,500rpms on start up then computer closes IAC Valve a bit to set cold idle at 1,100 or so
Remove IAC Valve from intake, 2 bolts
Plug in its 2 wire connector
Turn on the key
Watch the valve inside and unplug the 2 wire connector, valve should close, plug wires back in and it should open, it doesn't move that much but does/should move
Its just a solenoid with a spring so with wires unplug you should be able to move the valve manually


Clogged up exhaust can cause Lean codes, you can test for that with Vacuum gauge

 

Thats correct no EGR for this engine. The Idle control valve is new, still have the old one, I'll check its functionality, now plugged up exhaust did not think about that, I will look into it. I currently have a fuel injector cleaner in the tank. Thank you.

 

So i rechecked the fuel pressure, got a reading of 32 to 38 psi, fluctuates here and there. While running the psi is about 35, with the fuel regulator off the psi increases to 40, however the engine idle still kinda rough, took it into gear the first time after I was getting the symptoms....seems to hesitate a lot. TPS Still good, ICA still good, MAP still good. I removed spark plugs a bit of fouling from oil (leaky covers) replaced with new, cylinder 5 has carbon build up(running rich, or inadequate spark = distribotdi terminal was carbonized more so on cylinder 5 and 6). I'm am beginning to speculate more on a bad injector. What lbs of injectors are needed for the 92 ranger 2.9 automatic? Possible one of the injectors is not firing, I did a 15 minute pressure test(key off) no drop in fuel pressure to indicate a faulty fuel pump(return line valve) and no open leaking injector. Possible it just doesn't open when needed too.

​​​​​