WTH?
Roped into helping neighbor find why his Blazery thing is not running.

Distributor equipped 94?? 4.3 V6
Died on the road, now runs for 1 sec if given starting fluid then stops.

They changed the timing chain thinking that might be the problem. They said there was only one keyway, and the marks were aligned properly, so I kind of ruled out any fault with that.

I figured they got the plug wires out of order or distributor in 1/2 turn off or something easy.

Huh, no firing order written on the engine. Nothing on the useless underhood label. MIGHT be a "1" on a runner for front left intake. NO other clues except numbers on the newish plug wires, with 1 & 2 swapped and lying. I assume 135 down the LH side and 246 down the RH side.

Hard to get at #1 plug, google says firing order mate is #4, so I pull plug on #4, bump for compression, oops it went past. Mark timing slot with paint, turn crank CCW back to TDC, nope, that loosens the bolt.

OK, we'll turn CW, shoot for the next TDC = #1 firing position. Verify CW dist'r motion.

WTH??? There's TWO timing marks on this damper!!! now I have to GUESS which one is the one to use. Good Lord.

Line one up at TDC, rotor points to eh near #5 cylinder. Pick a cap tower near there, call it one, put wires on in order per info from the internet. No go. Oh I had 5 and 3 reversed.... swap, no better. Well, maybe the OTHER timing mark was the correct one. It was maybe a quarter [crank] turn behind the first one, so, 1/8 turn more CW- the next tower over CW.... redo the plug wires on that basis....

Back to starts and runs for one second if you give it spray, but then dies. So, pretty sure the plugs order is back to OK now.

Fuel pressure was verified at the rail by others before I arrived. I had to give up. I assume it's a computer sensor or wiring, and my expertise does not cover that stuff.... I had to suggest they see if they can get codes out of it, maybe it'll direct them to a crank position sensor or such. I see a MAP or similar on top of the intake, and another sensor, but none of us has a manual or clue sheet to narrow down possible causes.

Not expecting help on this issue, not sure I want to devote more time to it.

I did find this sort-of-explanation:
http://www.gm-trucks.com/forums/topi...ocedure-43-v6/

I just wanted to share my amazement that somebody thought it was a good idea to put TWO timing marks on a balancer.

 

iirc, one timing mark is the visual timing mark, and the other is the magnetic probe mark.
also, iirc, the injector spider is inside the clamshell intake. my '92 had an issue where the injector terminals had worn away to the point that the thing wouldn't run, except on carb cleaner. might be time to crack the clamshell. the injector/clamshell info is for the W motor 4.3, the Z 4.3 motor has boring throttle body injection.


bill

 

Did you remove the intake when the chain was replaced? If not, you might as well, as those engines are NOTORIOUS for intake manifold coolant leaks at the four corners.

IF it starts and runs with starting fluid, you know you have spark, and if you verified fuel pressure(35+ iir) you either have a "spider" injector connector problem or a computer failure that it's not firing the injectors. The injectors on the "W" code vin engine has the injectors hidden under the intake, so you must remove it and separate the two halves to work on them. A real pia.

If it suddenly just quit, i'd suspect a computer failure first. If you have access to a wiring diagram, you could pop the connector off the injector harness on the intake (you have to remove the fuel lines iir) and look at the connections.
Hope this points you in the right direction.

Greg

 

the W 4.3 only has 1 injector, there are 6 plastic lines that come of of it and are inserted into ports in the intake manifold, right near the intake valve. opening the clam shell(upper intake plenum) is not that big of a deal, except on an astro where it barely clears enough to come out. as i recall, fuel pressure should be at least 52 psi, that might vary depending on the year of W motor. i've seen a fix for the fuel injector connector pin wear issue, it's a rubber insert that goes under the connector to the fuel injector. and yes, it's 1, 3, 5 on the driver's side, from the front, 2, 4, 6 across the way. 1 piece of advice... do not try to start the engine with the clam shell removed, it will go instant WOT due to the air supply.


bill

 

I noticed him working on it again
He was into the intake
ayep there's a spider, aptly named.

Wires to it are repaired once and fubar'd again,
Some of the line holders-in broke off too

New $200-350 for the part.

He went boneyard $50 part and reassemble and voila good to go...

Thanks for the tips.

 

yw


bill