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I think this is the first time I've not figured out a problem...
Neighbor's truck is a 2000 one fiddy with the 5.4L.
270K miles and will not stay running after cranking.
Cranking with WOT has no fire so I know the computer isn't commanding the injectors open as designed.
Cranking with throttle body closed or partial open will start, rev up to 1100, drops to 300-500 while making light smoke, then stalls 30-ish seconds.
Oddly to me, it will rev up no smoke lightly spraying pulses of starting fluid.
Checked 40-45PSI on the fuel pressure before and after a new fuel pump/filter/pressure regulator.
O2 sensors are about 5 months old.
No codes are present key on engine running or not.
Live data showing 0 volts on the upstream O2 sensors, but I'm not sure if they get power until in closed loop.
Also confused on what an open loop fault is.
Foot to the floor while in sub idle running has no change to RPM
I would think white smoke is coolant, but it doesn't smell like it.
Seems more gray to me anyway.
I yield to the people smarter than me.
Adrianspeeder
Last edited by adrianspeeder; May 27, 2023 at 10:29 PM.
Open loop system fault means the O2 sensors aren't sending a signal back to the computer. The fuel system is running in default mode, although there are likely other problems too.
Reset the keep alive memory, but no dice on voltages except the one downstream.
That upstream passenger side connector is too hard to get to, but did verify no voltage at the upstream drivers side connector.
Then pulled the battery tray and computer bulkhead connector and continuity of that signal and return wire was good.
This is down the road so I'll go snag its computer tomorrow if it's a 5.4L.
So, I know it's a different animal, but I had this same problem on my 2007 Jeep Compass. After chasing wiring, I found out it was a loom of bad grounds.
If the engine will stay running with your foot on the gas,
my bet is the IAC is faulty.
The IAC has a Dash Pot function.
The round Can is a reservoir with a small hole in the diaphragm that if plugged with dirt or Carbon will allow the engine to start than stall.
You cannot clean it because it's inside the Can.
Take the Can apart ruins the IAC.
Good luck.
Gave the neighbor his money back for the truck as I felt bad selling it to him. Had this sitting out back since last summer as it was pissing me off for no reason why it wouldn't run with every single wire ohmed out from the computer and all parts testing good.
Decided I was going to tow to the pullapart yard quietly without telling anyone I was a ****ty mechanic for not figuring it out. But hey, there's a full tank of fuel in there. Cut the fuel filter output and put on a 25 foot hose to run to the wife's Jeep. Jumpered the fuel pump relay and let it do it's thing 'till empty. About that time Heather came out to say stop ****ing with her Jeep, it stalled... Uh oh. Pull out the rubber hose from the filler neck and it's clearly diesel fuel dripping. ****! To be half fair, the neighbor kid Airman I sold it to never owned a vehicle before. Grew up in LA. Thought trucks ran on diesel fuel.
Oh well. New fuel filter since I cut the one instead of dorking around with the fuel line tools, 5 gallons of new gas in the empty tank, and it fired right up. Drives fine. Had to pump out the Jeep into the PSD and Heather is happy again.
Leaded Gasoline Nozzle: outside diameter of 15/16" (23.8125mm) Unleaded Gasoline Nozzle: outside diameter of 13/16" (20.6375mm) Auto Diesel Nozzle: same as leaded gasoline Truck Hi-Flow Diesel Nozzle: 1 3/16" (30.1625mm)
The problem is that station mangers sometimes replace a broken Auto Diesel nozzle with an Unleaded Gasoline nozzle because they either have an extra or just order the cheapest available.
