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Discussion Starter #1 (Edited)
'95 4Runner, 2WD, 3.0l engine. Problem started while making 'Y' turn. Hit driveway, shifted into reverse, engine stalled and hasn't run since. Cranks fine, has spark (ignition timing is good) and fuel pressure (not out of gas). Turning key from 'off' position starts the engine but it dies within about one second. Turning key from 'on' position after initial dying produces only cranking---no running at all, even for the one second. Turning key back to 'off' and then start produces start and then die. I can't figure this one out. Something is turning off the fuel or spark. Truck was running fine before it stopped. Just completed top end overhaul--head gaskets, valve job, timing belt (checked valve timing--good), water pump, etc., etc.
Update 8/30/2013: Spark is good, fuel pressure is 45 psi. Suspect ECM has turned off injectors and running for short time is just residual fuel. Anyone know how to test for this, short of replacing ECM?
Update 8/30/2013, 5:37 PM: Tested for injector signal by jumpering the wires from one injector to another injector on a bench. Cranking the engine energized the test injector in both cases described in the original post. Really stumped now. Maybe I will recheck the TPS---perhaps it moved from where I had meticulously set it.
Update 8/31/2013, 5:42 PM:Suspected cold start injector so tested using the same method as above--injector sprayed less than one second then shut off. Rigged additional jumper so injector could spray continuously and engine started and ran until injector de-energized. Tried again, only longer duration--engine ran, revved up and sounded normal after de-energization, then slowly stalled, as if out of gas. Should have checked fuel pressure at that time but didn't--next time.
Update 9/2/2013, 9:14 AM: Fuel pressure checked out OK. Checked cold start injector time switch resistance--79 ohms, middle of acceptable range. Checked coolant temperature sensor--1.9 K ohms, again acceptable. Does anyone know how the length of time the cold start injector actually injects is determined? Mine appears to be energized for less than one second. Something is telling mine to shut off early.
While checking resistances I noticed what appears to be a thermally actuated pneumatic switch next to a single wire sensor next to the coolant temp sensor. Mine has only one tube attached, which goes to the top of the throttle body. Does anyone know the function of this switch and what is supposed to go to the unused port? I don't think this is part of my problem as it has always had only one tube attached. Curious. Never mind--I found the loose tube which goes to the charcoal cannister.
Update 9/12/2013, 8:39 PM: Swapped ECU for a neighbors--my ECU performed correctly in his and his ECU had no effect on my non-running problem. Did the same with his VAF and got the same result. I managed to run the engine by actuating the cold start injector from another voltage source and switch but as soon as I stopped injecting fuel manually the engine slowly died. It seems the injectors are not getting a proper signal to run the engine. I have checked everything I can think of and all have checked out OK. Stuck right now.
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