Need help! Strangest thing happened.

[mpio13]

My brother called & his 96 Tahoe wasn't starting at the gas station. After helping him out I cleaned up and headed out to my truck... Guess what? Crank crank crank, no start.
Messed with it for a bit; found it has no injector pulse or spark. It's a 1990 K5 TBI 350. What controls injector pulse and spark, the ignition module??
I had to leave it at work, I'll check it out tomorrow. Jut figured I'd ask you guys for some ideas.

 

[Fordum]

Well, the ignition module controls it on the older ones, I think it does so on that one too.

Of course, the computer does the actual controlling, but it gets it's data from there.

 

[Blue85]

The ignition module serves as an amplifier for the pick-up coil signal and sends that to the ECU. Then the ECU sends back a signal to fire the coil. So if that module dies the ECU thnks the engine is at 0rpm and you won't get any injector pulse except for whatever purge is built in (when the pump primes). So check the fuses first and make sure the ECU and module get power. Also check for a broken ground wire or strap from block to frame or body. Then you could look at a different ignition module.

 

[mpio13]

Since my brother had called I had a test light, a screwdriver some fuses & a pair of needle nose. So when mine didn't start; I immediately checked the fuses & connections. I listened for the fuel pump which came on. Then went for spark and injector pulse which were both missing.

Popped the ignition module in which a new cap & rotor and she fired right up.

 

[dhcomp]

Since my brother had called I had a test light, a screwdriver some fuses & a pair of needle nose. So when mine didn't start; I immediately checked the fuses & connections. I listened for the fuel pump which came on. Then went for spark and injector pulse which were both missing.

Popped the ignition module in which a new cap & rotor and she fired right up.

Check the condition of all the wires going into the ign module. I fried 3 before i got smart, and realized the insulation was cracked and these wires were shorting. Spliced in some new wire with waterproof heatshrink but connectors, and good as new!

 

[mpio13]

Not yet!

Update: NOT fixed. My previous post was a little pre mature; I had started my truck up but only for a moment. I did however back out of the shop and burn some rubber too.... But as I tried to leave work it acted up.

At first it started & idled just fine but when I put it in reverse it stalled. Then a few more time I refired and it idled but stalled in drive or reverse. Then it wouldn't even idle in park. Injectors seem to be spraying. It just dies.

I jumped the DLC and I think I got code 12? Not used to counting flashes.

Daren; thanks I'll check the wires. Looks like I might have to do some backprobing and such tomorrow. I've read elsewhere it could be an ECM or the distributor assembly itself?

 

[dhcomp]

Code 12 3 times tells you the diagnostic port is working. Each code gets flashed 3 times. Count the codes after that.


If its not idling, or dying when put into get, check into your fuel pressure status. How old is the pump? Weak pump, or clogged filter, and it may not idle in gear.

 

[mpio13]

Well... I'm pretty frustrated. This has all been happening at my work so of course instead of trying to fix my truck, my boss wants me to keep working on customers cars. Which is fine, just frustrating. I'm riding my V Star to work in rain and temps under 40. Not my favorite cruising weather.

So: it would actually idle.. As long as I was beating on the ECM with a screwdriver. Happened 3 times: idle while I'm tapping and stall as soon as I stop. So I ordered an ECM put it in and again, fired right up. Drove it around the building but as soon as I parked it it stumbled and died. Walked away for a bit came back with a 'brick' scantool and watched everything while it idled by itself just fine. Turned it off, tried to start it again and again, no idle at all...

I checked my distributor. Looked good. I think maybe they sent me a bad ECM? My boss said that used to happen all the time when they used to put computers in back in the day. The 'tap test' didn't work though.

I checked every wire & ground I could see... Nothing burnt, cracked, melted or otherwise shorted. Gunna try another ECM tomorrow. And yes, I swapped the proms over.

 

[Blue85]

Did you clean up the dizzy and use new thermal grease when you put the module in? Check the ground from the dizzy to the block? Do a visual inspection of everything in the dizzy - the carbon button, spring, rotor, cap, etc. Make sure the mechanical advance is springing back and not hanging up at 100 BTDC or something. A bad ignition coil can also cause intermittent problems. They especially like to cut out when they are hot.

 

[4xcrazy]

Someone else now having similar issues as mine with failing to stay running. At first you say failing injector pulse, now it is working? Mine is a failed injector pulse problem, or quite possibly a failure of supplying constant 12v supply. But being 2000 miles away, kind of makes it difficult to continuously diagnose at the moment. :-
And btw, TBI distributors don't have mechanical advance. ;-)

Keep us update please, if you figure this out. It may help others to determine similar issues.
Thanks

 

[mpio13]

I put a whole new distributor in. I determined the rusted points in mine were probably not putting out a strong enough signal as they past one another. Re-timed it and drove it around & around and all the way home.

I guess I could have hooked up to it and looked for the proper signal, but the way things were going it was basically the last item in the process of elimination.

 

[Blue85]

And btw, TBI distributors don't have mechanical advance. ;-)

Oops.

The rest of my post is valid, though. If the module is cutting out or the pickup is flaking out, the ECM will stop pulsing the injectors. It thinks the engine isn't turning. This is why distributors are bad. Too many failure points and wear items and maintenance.

 

[mpio13]

I cant complain... trucks 23 years old. 190,000 miles. Original motor and most likely the original distributor. Pretty good especially considering I live in damp New England and lots of those miles were not easy miles.

The distributor I put in is just a plain old OE replacement. Its gotta red cap which is pretty. One parts place pulled an ACCEL off their shelf for me because their computer said it was for my truck, I was all excited until they opened it and I saw the big ol' vaccuum module on the side... damn thought I was gunna get a cool upgrade. They did have an MSD coil right there though that looked right. Maybe I'll pick that up for some better zap? Or are they garbage?

Thanks for all the suggestions and help though fellas. Much appreciated. I'm so much more familiar with OBDII diagnostics than OBDI.

On top of my truck putting me through all this, a customer dropped off his 95 Grand Prix for lack of power... another tech threw a fuel pump at it which didn't work at all so the boss put me on it to figure out. Without a brick scanner it took me like 3 days (the scanner I used on my truck was borrowed on the 3rd day!) The brick finnaly showed me that it was in limp mode (puts it in 4th gear anytime in drive) because it was misfiring (which to me was amazing because I couldn't feel it missing, really it felt smooth).... anywho... just saying OBDI diags aren't my thing.

Thanks again!

 

[Blue85]

Well Accel ignition parts may be terrible, but they do cost more, which is a sort of "upgrade" for those who like to brag more than they like to drive.

I really doubt that cap and rotor were there for 190,000 miles. Glad you got it worked out.

 

[mpio13]

no, the cap and rotor i've changed many times. the distributor itself though, was original.
accell is junk huh? what about MSD, I hear mixed things about them. Or mallory...

 

[dyeager535]

Nothing particularly wrong with MSD, just not going to do anything for you over the stock setup in normal applications.