87 TBI - Intermittant "no start"

[Keith Seymore]

"Intermittant" problems are the worst kind....

As the title says, lil Red is an 87 4.3L V6, TBI, manual trans.

The presenting symptom is, on two occasions now, a no start. Vehicle will crank and crank and crank all day, but no fire. Won't even bark.

It happened once through the winter, when it was cold/rainy/damp. I played around with it a little bit, giving it little shots of starter fluid and sips of gasoline, to no avail. This led me to believe it was a "no spark" situation but I was not able to confirm. I ran out of time and - mysteriously - it healed itself and started right up the next time I tried it.

Same thing last night: I was leaving to go home from work. It was cold, wet, rainy (and dark) and the truck wouldn't start. Crank, crank, crank but no fire. I didn't have anything with me to work on it so I caught a ride home with my boss. When I retrieved the truck this afternoon (with every tool I own in tow) it started right up. Drove it all the way home with no issues. It is warmer, partly cloudy and very breezy today.

So - I'm getting a bit gunshy. My questions are these:

1) Does this sound like ignition to you guys?

2) Does this system have a module, like the old original HEI units? Is it susceptible to sudden and complete failure (like those were)?

3) Any additional thoughts? I'd like some input before I just start throwing parts at it. All of the ignition components could be original (cap, plugs, wires, dist, coil, etc). Truck now has just over 190,000 miles on it.

Thanks in advance -

K

[motornut]

replaced the fuel pump on my 87 350 tbi thinking it was toast
but got stuck couple of weeks later to look further only to find ,
a nick in a wire over the rear wheelwell ,
was baked hard and green and crusty when i cut it open

[1970SWB]

Keith, sounds like you have an ignition system breaking down, worse when its wet out, with it running spray down the plug wires & dist. cap with a squirt bottle of water, see if it begins to missfire, even if it doesn't I'd take a close look at dist. cap and coil wire.

[cr34t3d_by_d4rkd3n]

Originally Posted by 1970SWB

Keith, sounds like you have an ignition system breaking down, worse when its wet out, with it running spray down the plug wires & dist. cap with a squirt bottle of water, see if it begins to missfire, even if it doesn't I'd take a close look at dist. cap and coil wire.

BUT DONT MIST IT WITH WATER wtf??? just check for water, if waters getting in the cap or plug wire housings, it will still b there for a long time, when u pop the cap it will be quite apparent theres has been water exposure.......dont spray ur dist with water to diagnose problems... :duh:

Sounds like a neutral switch is corroded or getting wet. also check ur o2 sensor wires for when the trucks cold (water get to em) they create a short or a fault, when its hot and gets wet, it just evaporates..... if it IS the 02 wires, it would run rough then smooth out as it gets warm (usually)

ALSO

is computer does not sense oil pressure within 3 seconds of cranking the engine/and or/ running, the ecu will kill all spark...... food for thought.

[rfmaster]

Keith

You may have a flaky reluctor (pick up) coil. An intermittent connection at the ignition control module due to corrosion is a likely cause.

Alternatively, ignition coil used with small hat distributors are prone to fail due to age.

//RF

[ConZ]

check to see if the injectors are firing. friend of mine had a 92 305 tbi that would randomly no start. checked it out and it had no spark and the injectors werent firing. never figured it out though because everytime we would start to check things out it would go back to normal. hope this helps

[1970SWB]

Originally Posted by cr34t3d_by_d4rkd3n

BUT DONT MIST IT WITH WATER wtf??? just check for water, if waters getting in the cap or plug wire housings, it will still b there for a long time, when u pop the cap it will be quite apparent theres has been water exposure.......dont spray ur dist with water to diagnose problems... :duh:

Sounds like a neutral switch is corroded or getting wet. also check ur o2 sensor wires for when the trucks cold (water get to em) they create a short or a fault, when its hot and gets wet, it just evaporates..... if it IS the 02 wires, it would run rough then smooth out as it gets warm (usually)

ALSO

is computer does not sense oil pressure within 3 seconds of cranking the engine/and or/ running, the ecu will kill all spark...... food for thought.

Spraying water on an ignition system is a VERY COMMON diagnosis procedure to see if you have an ignition breakdown, even at a GM dealership where we "have all the correct tools" if the truck runs fine when dry out, and not when its wet, I believe that is his problem. You are correct that if he removes the cap he should see evidence of moisture, but... if it is a coil wire breaking down you can easily find that by "spraying it with water mist"

The neutral switch problem you mention would keep it from cranking(besides it would be a clutch switch being this is has a manual trans), and the O2 sensor MAY set a code but would NOT create a no start condition.

A no oil pressure computer shut down problem shouldn't be intermentant, and would still fire and run for a couple seconds atleast.....

Hope this helps Kieth!!

[tucsonjwt]

No start in wet conditions always used to be distributor cap or plug wires. I always use Belden wires from NAPA. I ultimately needed an upper steering column rebuild to fix intermittent no start. Other usual suspects are clutch neutral switch and ignition switch.

[SS Delux]

I would do a tune up on the cap, rotor and all that good stuff if you are saying you think it might be original. Little bit off topic though, what tranny does your truck have ? I have and 87 as well with the 4.3L V6 and a 4 speed NP A833. Not trying to hijack :P

[Keith Seymore]

Thanks, guys - good thoughts. I'm tracking right there with ya -

John Stevens - thank you; very helpful. Are you over at V8Buick.com, too?

SSDelux - it's the RPO "MY6" trans, with is the New Process one that you mention. You can see reference pics throughout my build thread, linked below.

Thanks again, everybody.

K

[1970SWB]

Originally Posted by Keith Seymore

John Stevens - thank you; very helpful. Are you over at V8Buick.com, too?

Keith, I've been in a GM dealership for 17+ years, won't say I've seen it all but have my share anyway... Yes, I'm on the V8Buick board as well, I've been a Buick Geek for years(born and raised in Flint) & have been to every GSCA nationals since '85. I recently bought a '70 SWB Chevy to go along with all my other projects that I'll be lucky to ever finish.

[CLASSIC87']

I had a problem like this one time... and my battery end up having a bad cell. Just an idea...

OOPS.. never mind I reread your post and you are getting power. Sorry

Good luck,
Anthony

[D13]

Do you want to diagnose it or fix it?
Fix - rebuild a distributor with a new GM module, GM pick up coil, Delco cap and wires. Check and clean the connector at the distributor. Replace the coil w/ new GM.

Diagnose - no start with added fuel means no spark (TBI uses distributor pulse signal to ECM to run fuel too). That means module (70%), pick up coil (15%), coil (10%), or distributor worn so that pick up isn't working correctly (which will lead to pick up coil failure) (5%).

For what it's worth my 1990, which had the same basic system, would eat a module and coil every Christmastime for 3 years straight, while it was cooler and damp out. The last time I replaced the Accel plug wires that I had put on at 125,000 miles, turns out 1 wire was bad, back feeding the module, which then was buring out the coil. No more issues for the next 3 years (sold the truck).

Part house modules are cheaper than Delco because they take the RF filtering out of the chip, much more fragile to stray voltage (like, a bad plug wire...). Learned that when I was a service guy for Oldsmopile. Pick up coil wires and distributor connection wires like to corrode and crack inside the connector. After my experiences with aftermarket plug wires I'm convinced nothing is better for a DD than a set of Delcos. Unless you can find 70-80's Packard NOS - the best made.

[Keith Seymore]

All better now -

I finally received all the ignition parts I ordered (plugs, wires, coil wire, cap, rotor, ignition module and coil) and tore into it yesterday.

Turns out it was the distributor cap, and corrosion in the coil wire. The coil post came right out in my hand upon dissassembly.



After installing a new cap, rotor and coil wire it's like a new truck again. Fires right up and peppy as a puppy!

Thanks for all your input!

K

[Desert1957]

Hey Keith,

Glad you found your problem, just a note about your Distributor. They have a problem with the top bushing wearing out causing excess play. Check the rotor by pulling side to side on the shaft. If its bad it causes some drive-ability issues,

Desert