Engine starts then stalls immediately

[Podor]

It almost sounds like there is still a passlock issue. We know fuel pressure is good. It may be helpful to put a noid light on an injector and a spark tester on at the same time and see what happens. I can't remember if the security system cuts fuel and fire or just fuel. If we are losing both at the same time, I would almost say the passlock is still an issue. It could be cam or crank signal dropping out, but that is almost never an issue on these, as far as I can tell. If I were still I a shop with a scope, I would probably watch cam and crank signals and see if they drop out. Not really a possibility in most cases.

[BlueBloodOval]

Same problem with 2001 Chevy 1500 truck with 4.8 litre engine.

Truck ran fine then was stolen. Towed home as battery and relays were missing.

Ignition lock housing was drilled out between the housing and key tumbler joint, looked like a 3/16" drill bit. Current tag also ripped off. (Oakland Calif. go figure).

Replaced battery, relays, new GM ignition lock housing with key and tumbler. Assembled tumbler with key several times with different gear tooth combinations until we had off, rotate to ignition on,  rotating key more to start position. From key off position rotate key the opposite direction to accessory position. No other tooth count combination will allow this full rotation of key functions in both directions. Will assemble steering column and wheel after truck is finally running. That shouldn't cause a no run condition?

Crank with no start, dead fuel pump now replaced we have fuel and spark.

It will start and run 3/4 of a second with app 6-8 cylinders firing in order then dead. Can repeat start and dead 20 times thinking air in fuel system requiring purging air out. Heck return fuel line loop should cure air in system problems.

On those short start run bursts the oil pressure rises to 60 psi.

The "SECURITY" dash light is on and blinking. I haven't checked fuel rail pressure as well run a scan tool at this time. 

This a "SECURITY" "passlock" computer fuel shutdown the problem on this 2001 truck? Been told newer trucks 2004 up required dealership computer clearing $$$$? How to clear it if the computer is the problem? Already  tried "ignition on and off three times within 10 minutes". Already tried other "clear the  computer" tricks and ideas with zero luck and running again.

The low oil pressure "cut out" sensor a  no run cause problem?  Where is this low pressure cut-off switch located to bypass jumper it?

At whit's end! Parked dead on the street (not Oakland) three months fighting this truck daily after work in the dark and rain before the cops have it towed.  

Thanks in advance. "CJ"

Edited January 30, 2019 by BlueBloodOval

[Big_Daddys_Caddys]

Any update from anyone?

[Big_Daddys_Caddys]

Hi guys,
I'd need a bit of help here please:
An '05 6L, when cold and it has to start on the fast idle, it will turn over and run just fine. (99.9%).
And (intermittently but often enough) once its warm, it will start, run for a second then stall right out. Exactly like if it had set off the Passlock system but the Passlock security light acts normally and doesn't flash or stay on. It doesn't hesitate, or buck on its way to stalling, the needle just drops like a rock. Also, it has no Check engine codes. When the truck is running, everything about it seems just fine, no hesitation, no bucking, great acceleration, smooth as silk. I would be inclined to check the Idle Air Control valve but I'm not even sure if it has one or not but for some reason I really think it is a security issue that is preventing the truck from running normally because when it does operate normally, it sounds great.
Thanks for any help you could offer.

[riverbanks]

You say,no codes,is that going by the light or scanning?

[Big_Daddys_Caddys]

Both.

[riverbanks]

It is possible for the crank sensor to act that way,one way to check is spray it with cold water, another possibility,what about a wire wiggle test while it's behaving,behind power steering pump is a rub spot,see if you can get it to stall

[sefiroxx]

The iac function is computer control of the throttle/tps part of the throttle body.

[Big_Daddys_Caddys]

Thanks for the reply Riverbanks, just one thing: in the world of cars, I have no idea what a rub spot is and does...

[Big_Daddys_Caddys]

Thanks for the reply Sefiroxx, on older models of cars/trucks I have seen, there was a separate IAC unit with motor & rubber round tip that would open/shut for more/less air mix. They would get cruddy and would need a good cleaning every so often. On these throttles is there any such separate unit or passage that may need to be cleaned? 

Edited January 8, 2020 by Big_Daddys_Caddys

[riverbanks]

Sorry,I should be more clear,Wire harness failure, rubbing, possible short or open in circuit

[stanvanover]

This may have been mentioned but did not see it reading through. When I have done motor swaps I have run into an issue where the oil pressure switch was bad and would have this symptom. Worth a try good luck!!!!

Sent from my SM-N960U using Tapatalk

[stanvanover]

Hi guys,
I'd need a bit of help here please:
An '05 6L, when cold and it has to start on the fast idle, it will turn over and run just fine. (99.9%).
And (intermittently but often enough) once its warm, it will start, run for a second then stall right out. Exactly like if it had set off the Passlock system but the Passlock security light acts normally and doesn't flash or stay on. It doesn't hesitate, or buck on its way to stalling, the needle just drops like a rock. Also, it has no Check engine codes. When the truck is running, everything about it seems just fine, no hesitation, no bucking, great acceleration, smooth as silk. I would be inclined to check the Idle Air Control valve but I'm not even sure if it has one or not but for some reason I really think it is a security issue that is preventing the truck from running normally because when it does operate normally, it sounds great.
Thanks for any help you could offer.

I had Same problem I switched to the 160amp alternator and changed battery. Solved the issue.

Sent from my SM-N960U using Tapatalk

[Big_Daddys_Caddys]

Got this truck not long ago and it needed a new transmission. It started fine and idled great before I got it but couldn't move because of the transmission. Meaning we never ran the engine for any real length of time, it never really got hot and there never was any day-to-day start-it-stop-it, go-here-go-there thing happening. Once we swapped in a used tranny, when we started running the truck for longer periods, that is when the start-stall issue began. All of the posts led me to the Passlock issue, because it is exactly what the passlock security does: Starts the engine, runs for a second, then just dies. So it was OBVIOUS! HOW COULD IT BE ANYTHING ELSE??? We jiggled wires, we looked for weak connections, we checked voltage & fuses, we thought of changing the tumbler, the key, even over riding the passlock system --- Then --- we opened up the air filter housing to get to the air intake for a throttle body clean out ---> It was the Sahara desert in there. Sand, dirt, sh*t, you name it, all there. Cleaned everything out like a surgeon ---> hasn't done it in two days!

Moral of the story - Don't get too locked into pursuing ONE solution, even if the internet says so. They can be wrong.

Thanks for all of your help guys, I hope this post will serve someone in the future.

Edited January 10, 2020 by Big_Daddys_Caddys
Grammar

[riverbanks]

Thanks for the update,glad you're fixed,live&learn,that's what we're all doing