97 5-L Starts, immediately dies

[Naftaturbo]

Update:
I replaced the fuel pump with a new Delphi. Fuel pressure with engine off is about 20PSI, and for the few seconds that the engine idles it is about 40 PSI. Fuel flow is good. Idles smooth, then dies after a few seconds of idling.
CEL is on with KeyOnEngineOff. CEL goes out while cranking. No codes.
Could sure use some help/suggestions.

Truck sat for about 3 months because radiator started leaking and I had to have surgery and then recover. Truck was running very well when I shut it down to remove radiator.
. Doc said I could start working again so yesterday I replaced radiator and checked for leaks.
. Tried to start truck and it would fire and run for about 3 seconds then die; noticed that fuel gage showed empty (apparently someone siphoned fuel out). Put in 4 gallons of fuel and same symptom: fired and ran for ~3 seconds then died. No OBD codes.
. Removed connector from inertia switch so I could run 12V directly to pump (pink/black wire). Now engine ran for about 20 minutes which allowed me to check cooling system at temperature and pressure and confirm no leaks. I backed truck out of driveway and parked it on the street.
. I let truck cool off for about 20 minutes while I cleaned up and was going to drive it to gas station to fill up. When I tried to start to drive to gas station the same problem started again. (Note, I'm still running 12V directly to pump through the inertia switch connector).
. Borrowed a fuel press gage from Auto Zone. Connected to Schrader valve on fuel line. Pressure builds up to 40 PSIG. Crank engine, fires for about 3 seconds then dies; during the 3 seconds fuel pressure holds at 38-40 PSIG. When the engine dies, pressure continues to hold at 40 PSIG.
. If I hold throttle wide open (stops signals to injectors?) the engine will fire and run up to ~3000 RPM then start to die off. If I feather the throttle I can get it to stay running (stumbling) a few more seconds and even idle for a few seconds. Fuel pressure stays at 38-40 the whole time.
. I then tried to do an engine off (12V to pump) fuel flow measurement by using the gage set's pressure relief button and draining into a quart container - I was going to time how long it took to fill. As soon as I pressed the relief button the pressure dropped off to about 10 PSIG with ALMOST NO FUEL FLOW.
. I'm now in a quandary:
(a) no fuel flow through the relief valve into the container and a drop in pressure (the pressure came up again when I closed the valve) I guess indicates the pump is bad (pressure but not enough flow) and the engine isn't getting enough fuel to even idle. But
(b) Since WOT causes it to run few seconds longer (and at high speed) when the injectors get no signal (should be closed), I'm wondering if an injector or two might be stuck open, not closing due to dirt, or some other injector issue causing engine to die due to excess fuel (flooding rich)? Still no codes.
. Anyone had a pump that delivered pressure but at such low volume that engine wouldn’t run? Since pressure stays at 38-40 for the few seconds engine runs (and stays at 40 when engine dies) I’m thinking this is a long shot…
. I don’t think its IAC because even if I open the throttle a bit when engine starts, it still dies off…
. Open to ideas and suggestions. PLEASE!

 

[Naftaturbo]

trying to bump up to see if I can get any help/suggestions...

 

[Turdle]

when it dies, does the check engine light come on?

 

[Naftaturbo]

Yes, when it dies the CEL comes on.

 

[Turdle]

Next question, does it stay on while running?

I do not see fuel filter in the list of replacement parts. It may be clogging up.

Is the truck parked level or is it on an uphill incline? You might just need more fuel in the tank-

 

[gatzdon]

I'm leaning towards a possible fuel filter issue limiting flow.

If you have your own OBDII reader, try to use Forscan or Forscan Lite to pull the extended error codes. OBDII codes are for emissions related codes only. You may get lucky and have a code that points you in the right direction.

 

[Naftaturbo]

Fuel Filter replaced at same time as new Fuel Pump.
During the few seconds it's running the CEL is OFF. When engine dies, CEL comes on (steady).
The truck is parked level. There's a total of 4 gallons of fresh fuel in the tank I know about (I put them in there from a jerry-can), there may be another 1/2 gallon or so I don't know about.
I have a very basic OBD scanner (Autel MaxiScan® MS300 OBDII CANBUS); don't have access to Forscan (is that a laptop software?). The Autel MS300 doesn't give me any codes.

 

[Bobmbx]

I vote for fuel filter. Its a cheap fix, and even if it isn't the problem, you've got a new filter.

EDIT: I didn't see your last post about the new filter.

If you've got the time, try a heavy dose of Gumout or Seafoam in the fuel system. You might have a shot of jellied fuel in there somewhere restricting flow.

 

[gatzdon]

Fuel Filter replaced at same time as new Fuel Pump.
During the few seconds it's running the CEL is OFF. When engine dies, CEL comes on (steady).
The truck is parked level. There's a total of 4 gallons of fresh fuel in the tank I know about (I put them in there from a jerry-can), there may be another 1/2 gallon or so I don't know about.
I have a very basic OBD scanner (Autel MaxiScan® MS300 OBDII CANBUS); don't have access to Forscan (is that a laptop software?). The Autel MS300 doesn't give me any codes.

If you are serious about keeping the vehicle on the road, I would invest in a Bluetooth OBDII Scanner and Forscan Lite for your smart phone. I know this is pretty new for most in this forum, but I'm amazed at just how much information we can get out of our vehicle without even popping the hood.

the ODBII scanner should work for every vehicle 1996 and later. I bought mine to troubleshoot my 2000 Ex, but was able to use it to troubleshoot an evap issue on my 2012 Ex, so for me, it's the one tool that really keeps paying for itself.

If your fuel pressure is dropping off with even the slightest fuel flow, I would probably be looking for an obstruction somewhere, either the fuel filter, or the line from the tank to the fuel filter.

 

[Naftaturbo]

I decided to disconnect the MAF connector. With the connector off, the engine started right up and idled smoothly. It wouldn't take much throttle, but that was not unexpected.

I noticed that a couple of the connector wires were bent "funny" and checked them but they seemed to conduct OK. Then opened up the MAF and found that a spider had spun it's web around the sensor wires and blocked the air intake to the sensor. Cleaned that up with contact cleaner and tried again. Without the MAF connected the engine started and idled smooth. As soon as I plugged in the MAF connector the engine died.
So I purchased a new connector and a new MAF.
I just finished replacing the connector, having cut the harness wires back about 1" and splicing the new connector's leads to the harness wires. Soldered and shrink wrap.
Didn't plug in the connector 'cause I wanted to see if the engine would still idle smoothly without the MAF. It wouldn't start (cranks good, good fuel pressure).
Noticed the Check Engine light wasn't on so I checked the PCM maxi-fuse. It was blown. Swapped in the fuse from the rear defroster (also 30-amp) and that one blew as well.
So now I have that problem to deal with. Anyone know what can cause the PCM Maxi-Fuse to blow?

 

[Turdle]

I have to wonder if the new harness and connector has an internal short, ( defect)

 

[Naftaturbo]

Yep. Going to dismantle all my work and check it out. The harness isn't new - I meant that the new connector came with leads already attached. So I cut the old connector off the engine's harness, about 1" back from the connector to get to "clean wire" and soldered the new connector's leads to the engine harness.
At this point I'm going to hope I missed a sliced wire or something...
BTW: the original connector only had 4 wires. The new one had 6; of course I just didn't use the two that aren't needed (the 2 outer ones). The connector fits fine otherwise onto the MAF so I can't imagine that's a problem - but does anyone know more about the 4-wire vs 6-wire? Is the 6-wire supposed to have some internal connection within the connector? I'm really reaching here...

 

[Naftaturbo]

Turns out there was a short in the harness 'upstream' of the 1" I cut away. The wire insulation is starting to harden and crack and my moving it around caused some uninsulated contact between the 12V power wire and the main ground wire. I cut the harness further back to get away from the damaged insulation, re-spliced the new connector and that now seems to work OK. no more blowing the fuse.
Again, with the MAF not connected the engine started and idled smoothly. As soon as I plugged the connector into the original MAF the engine died. So clearly the original MAF was not 'saved' by my attempt to clean it. I installed the new MAF and connecting it doesn't cause the engine to die. However, other than idle, the engine runs poorly. It doesn't want to accelerate and I get some backfires into the intake manifold/throttle-body. I'm hoping that's just because the PCM needs to calibrate to the new sensor. I let it idle for about 20 minutes last night, and will try to take it out for a drive today. fingers crossed...

 

[Naftaturbo]

My Explorer is back drivable again. It ran pretty poorly at first but after letting it idle for 20 minutes it started and drove well. This morning I put about 26 miles on it and it ran smooth and with about the same power as I remember it having.
The only problem left is cold starts. When I started it this morning, it struggled to idle. I could keep it alive by working the throttle, particularly going WOT a number of times. It is backfiring a lot into the intake manifold/throttle-body. After a few minutes of playing with the throttle, living with the backfires, it started to idle and I was able to drive away - no problems after that.
I'm thinking I need to start checking temperature sensors (particularly the two-wire sensor in the inlet duct between the MAF and the throttle body), but if anyone has experienced something similar and can offer other suggestions, I appreciate them.

 

[Naftaturbo]

Mostly Resolved, 1 little item left: 97 5-L Starts, immediately dies

As I said in previous post, my truck is back on the road. Seems to run well and idles smoothly after a short warm up. But cold starts (overnight) are still very bad. Idles for 30 seconds or so then starts to die. If I keep it running by opening throttle (as much as WOT) it'll stumble and keep running and I get (lean) backfires. After a few minutes of nursing the throttle I can drive off and everything is fine. I just checked engine off codes and got the two banks lean (P0171 and P0174).
I'm thinking I need to start checking temperature sensors (particularly the two-wire IAT in the inlet duct between the MAF and the throttle body), but if anyone has experienced similar symptoms and can offer other suggestions, I appreciate them. Does anyone have access to resistance readings vs temperature for the IAT used on '97 5L?
thanks,,,