Help! Starts strong. Dies instantly. Every time.

[khigh]

This on a 2000 Z-Z1 Tahoe OBS 350/5.7 - stock engine except K&N kit.

It's been in storage, sitting since 08-31. It's started once since then just to test it. Can't remember exactly when - maybe halfway through. Maybe closer to the beginning. I just fired it up briefly from the remote to make sure it started and it did.

Dual AGM batteries in parallel. One was disconnected during storage.

Today I went to get it and it showed no sign of life. I hooked up the second battery and it cranked strongly in a rev or two. Died after a second. Same symptom every single time. Worst case is 4-5 revs - fires strongly every time - never any sputtering or hesitation. It roars to life and dies within a second - never shows any sign of even trying to run longer.

I didn't get to do much in the way of diagnosis - picking up the truck from storage was part of some weekend plans I had to continue on without it. I'll pick it back up on Monday. I can take basic hand tools, but I can't really tear the whole thing down where it sits. I do have a BT OBDII Dongle, but not sure if it's even running long enough to generate codes.

The ONLY thing I can think of (in retrospect or I would have tried it) is maybe the original battery is so dead it's causing too big a drain on the alternator even though there's a good battery in it? Feels like that's reaching, but it's all I got. Or maybe a stuck sensor?

Any ideas what to look for?

Thanks for looking.

 

[swathdiver]

Next time, turn the key to the on position and listen for the fuel pump. Check codes then too and bring some juice for those batteries (distilled water, jumper cables, etc.).

 

[east302]

In addition to swath's suggestions above, is the "Security" light staying on or flashing on the instrument cluster? If so, that's probably the Passlock security disabling the fuel injectors.

 

[khigh]

Thanks for the replies.

I don't think I've ever seen a "Security" light. Was that an option?

 

[khigh]

Hmmm - reading about Passlock, I guess I could have it. Started in the mid 90s? I have a third party remote start, so it may have been permanently disabled? I'd never encountered it before.

BUT.

I did try the remote start, nothing. I hooked up the battery, Then started with remote start again. But later attempts were with the key. Now I'm reading something about leaving the key in for ten minutes? But what I'm seeing about Passlock is a no start - not a start and shutdown. Another thing to try, anyway.

 

[khigh]

It's doing exactly this. Except I don't know if there's a light that says Security because I wasn't looking for it. It stands to reason it would be there.

 

[east302]

Yeah, next time see if the security light comes on. Normally, it should come on solid for a few seconds with ignition in run (not start) and then go off.

 

[khigh]

OK my theory now is I tripped the security by attaching battery and trying to use the remote start.

Meaning the thing that ruined my weekend plans is... a "feature".

 

[east302]

Lol, that kind of thing happens to me all the time

 

[willxfs]

Yep. Its the passlock security feature. You need to do the relearn procedure. I have a 1998 tahoe that did the exact same thing to me after I had the computer reflashed. I can see in your video the security light flashing in the upper right corner of your instrument cluster. It will probably stay on solid if you leave the key in the on position. Google passlock relearn and try it. Goes something like try to start truck, it dies, leave key in run position for 10 minutes. Then turn to off position and try to start again. May take a couple of tries. Good luck.