Yellow Spark No Start

[Frank Enstein]

Believe it or not a new battery fixed it so far as anyone can tell seems to be true but don't quote me on it 'cuz I don't trust the accursed thing as far as I can throw it.

There! I said it all in the same sentence so the *^^&%#&^ thing doesn't think I trust it.

It had the hiccups a couple of times on the test drive after a hot restart. I'm thinking that's what you get when you reset the block learn on a vehicle with 290,000 miles on it. Prolly needs a few adjustments methinks.

So in a fit of unbridled stupidity, we are taking the whole family 3 hours away in it to go to a "Look at the Pretty Trees Before all the Leaves Fall Off Them and You Freeze Off Your Naughty Bits for the Next Three or Four Months" train ride.

Assuming it starts.

Put your hands on the radio and pray with me...

 

[Schurkey]

Believe it or not a new battery fixed it so far as anyone can tell seems to be true but don't quote me on it 'cuz I don't trust the accursed thing as far as I can throw it.

Mmmm...I don't think so. But I've been wrong before.

It had the hiccups a couple of times on the test drive after a hot restart. I'm thinking that's what you get when you reset the block learn on a vehicle with 290,000 miles on it. Prolly needs a few adjustments methinks.

Does losing battery voltage reset the Block Learn? If it does, it should reset the trans adaptions, too.

I thought that stuff was in non-volatile memory--stays intact even with the battery disconnected.

So in a fit of unbridled stupidity, we are taking the whole family 3 hours away in it to go to a "Look at the Pretty Trees Before all the Leaves Fall Off Them...

Good family fun. And there'll be plenty of hands to push the van back to civilization if it croaks.

and You Freeze Off Your Naughty Bits for the Next Three or Four Months" train ride.

Three or four months? I should be so lucky.

 

[Frank Enstein]

OBD1 clears everything and goes back to default settings when the battery is disconnected.
I conformed this with the live data from the code scanner.
OBD2 keeps everything intact.
The Astro is TBI and a 1994

 

[PlayingWithTBI]

OBD1 clears everything and goes back to default settings when the battery is disconnected.

It even resets when <8VDC IIRC.

 

[Frank Enstein]

Annnd it wouldn't start this morning so we took Frank to the train ride.
Three hours each way and my son is playing on his mom's phone.

 

[Frank Enstein]

During testing trying to get it to start I added a few extra temporary ground wires to no effect.

O.K. so here's the plan;

Pull codes and see if any of the values for the live data are significantly different from what they were when it ran. Like 0 volts from the MAP or something.

Get a pinout and test every wire to find the momentary short/open that is causing the no start. I'll check for continuity and see if the resistance value changes when the harness is moved.

Anyone have a pinout for the PCM for a 1994 4.3 TBI? I assume the Astro PCM and a C1500 4.3 would be the same (I hope).

Can't touch it until Sunday. I can however stew about it all day Saturday @ work.

Any other thoughts of what I should check while I'm at it?

It has to be a wiring break/short because it runs smooth and strong when it does start and is a doornail when it doesn't.

It has run on starting fluid so it's less likely to be ignition. I did see the injectors spraying when cranking/no start so maybe not.

I have hot-wired the fuel pump as a test (I keep a relay jumper wire under the hood) with no start so I have at least excluded that as a possibility.

Thanks again folks.

 

[Schurkey]

I think you have it covered. At least, I'm out of ideas.

 

[Frank Enstein]

Thank you.