'91 305 TBI stalled out, got towed, never started again

TheAutomaTom · Jul 16, 2024

@HotWheelsBurban , as much as I would appreciate having you second guess everything I've already stated here in person, a forum thread is different since you can see the entire history of this conversation. Please refrain from long rambling distractions. I'd very much like you to remove your lengthy, snarky contribution, please sir.

Stated again to focus the topic:
"I would love to hear from someone who has experienced symptom where "motor only starts with timing advance unplugged." That was the main, unique thing, for a while.

Unplugging that wire is part of the process of setting base timing. Plugging back up means that the ECU takes over timing after 400 rpm. I can't find an issue with the physical wiring."

Thank you, internet people.

DerekTheGreat · Jul 16, 2024

TheAutomaTom said:
"...only leaves the timing of the spark."

I would love to hear from someone who has experienced symptom where "motor only starts with timing advance unplugged." That was the main, unique thing, for a while.

Unplugging that wire is part of the process of setting base timing. Plugging back up means that the ECU takes over timing after 400 rpm. I can't find an issue with the physical wiring. A replacement ECU didn't impact the issue, and everyone says the 2 chips basically can't go bad... But wtf, right?

How about trucks that would start, but wouldn't idle below 1,000 rpm with the EST wire connected? Both were 350 five speeds, an '89 and '92. Actually, the '92 died on the expressway and wouldn't restart until I unplugged that wire.

The first time I encountered that was after changing plugs, wires, cap and rotor on the '89. I went to start it up and it did, but would die when it tried to idle under 1,000 rpm. The '92 just flat out quit. In both cases, unplugging the wire got me to the parts store. And in both cases, I simply replaced the distributor with one that was complete with cap, rotor & ICM. I read a post from Schurkey where the reluctor wheel(?) on the dizzy can crack and the dizzy's shaft can become sloppy, so that's why I just stabbed distributors in. The '92 never had that problem again, least not to my knowledge. My '89 later developed a fluttery tach (always fluttered for a few moments when first started) which eventually stranded me on the freeway a year or so later. Stabbed another new dizzy in it back in October and the was back on the road, no tach flutter whatsoever.

TheAutomaTom · Jul 16, 2024

DerekTheGreat said:
How about trucks that would start, but wouldn't idle below 1,000 rpm with the EST wire connected? Both were 350 five speeds, an '89 and '92. Actually, the '92 died on the expressway and wouldn't restart until I unplugged that wire.

The first time I encountered that was after changing plugs, wires, cap and rotor on the '89. I went to start it up and it did, but would die when it tried to idle under 1,000 rpm. The '92 just flat out quit. In both cases, unplugging the wire got me to the parts store. And in both cases, I simply replaced the distributor with one that was complete with cap, rotor & ICM. I read a post from Schurkey where the reluctor wheel(?) on the dizzy can crack and the dizzy's shaft can become sloppy, so that's why I just stabbed distributors in. The '92 never had that problem again, least not to my knowledge. My '89 later developed a fluttery tach (always fluttered for a few moments when first started) which eventually stranded me on the freeway a year or so later. Stabbed another new dizzy in it back in October and the was back on the road, no tach flutter whatsoever.

Thanks for that! Yeah, it's killing me that the complete warranty replacement distributor didn't get it going. I even tried swapping with a spare ignition module.

The shaft can only seat 2 ways... the gear at the bottom has a pin to set the alignment, so that too can only be assembled 2 ways, which are effectively identical.

Schurkey · Jul 16, 2024

TheAutomaTom said:
The shaft can only seat 2 ways.

Not if you turn the oil pump drive shaft. The distributor can be seated with any of the teeth on the gear meshing with the gear at the back of the camshaft.

I'm not saying that it doesn't matter which gear tooth aligns with the cam gear--although if the distributor has enough room to rotate, and you're willing to screw-around with the plug-wire position on the distributor cap, accommodation can be made and the engine will run.

TheAutomaTom said:
the gear at the bottom has a pin to set the alignment, so that too can only be assembled 2 ways, which are effectively identical.

Again, no. The distributor gear has 13 teeth. The roll-pin is aligned with a tooth on one side, and the valley between two teeth on the other side. The gear can be installed correctly--the dimple on the gear aligning with the conductive rotor tip--or incorrectly, half-a-tooth off.

Half-a-tooth-off can be useful especially on some Vortec distributors that seem to have problems getting the cam sensor signal to synchronize with the crank sensor signal.

docstoy · Jul 17, 2024

Thinking about advance and retard, disconnect your knock sensor and after cleaning spark plugs to remove fuel from multiple no starts try to start again

Scooterwrench · Jul 17, 2024

I think you may be messing up thinking the dist. only goes in one of two ways and your dropping it in way out of time. The correct clocking of the dist. is with the cyl. #1 at the top of the compression stroke,the ICM pointed towards the drivers seat and the rotor pointing at #1 cylinder. You may need to reach down in there with a long flat bladed screwdriver to turn the oil pump shaft to align with the dist. for it to drop all the way in. You match the oil pump shaft with the dist.,not the other way around. When done right the points on the reluctor will line up with the points on the pickup coil. Get it all lined up right and it will fire right up and be very close to being in time.

TheAutomaTom · Jul 19, 2024

Schurkey said:
Not if you turn the oil pump drive shaft. The distributor can be seated with any of the teeth on the gear meshing with the gear at the back of the camshaft.

I'm not saying that it doesn't matter which gear tooth aligns with the cam gear--although if the distributor has enough room to rotate, and you're willing to screw-around with the plug-wire position on the distributor cap, accommodation can be made and the engine will run.

Again, no. The distributor gear has 13 teeth. The roll-pin is aligned with a tooth on one side, and the valley between two teeth on the other side. The gear can be installed correctly--the dimple on the gear aligning with the conductive rotor tip--or incorrectly, half-a-tooth off.

Half-a-tooth-off can be useful especially on some Vortec distributors that seem to have problems getting the cam sensor signal to synchronize with the crank sensor signal.

You're right: 13 teeth, excuse me. Flipping the gear around by the pin resulted in no-start. After a bunch of twisting and tweaking, I reinstalled it the original way and I'm back at the 30' ATDC start. I'll spend more time turning the oil pump out of sequence with the distributor this weekend. Thanks.

WICruiser-97 · Jul 19, 2024

30 degrees ATDC is really off in terms of operation, is it possible that the damper key is displaced or the indicator mark you are using is not correct?

Scooterwrench · Jul 19, 2024

WICruiser-97 said:
30 degrees ATDC is really off in terms of operation, is it possible that the damper key is displaced or the indicator mark you are using is not correct?

I'm thinking the ring has spun on the hub. A way to tell is by putting a screwdriver into #1 spark plug hole and rotate the engine until the piston is at the top then go a little further till you feel the screwdriver start to go back down and mark the balancer at the 0 timing mark. Back the engine up until you feel the screwdriver come back up to top and start back down and mark the balancer again. If the original timing mark is not close to being in the center of your marks the balancer ring has spun.

scott2093 · Jul 19, 2024

Scooterwrench said:
I'm thinking the ring has spun on the hub.

Once it does, is it possible to put some witness marks on it and fire it up to see if there's a shift? Or can it actually settle in to a spot and the marks stay there even after startup and running for a bit?

'91 305 TBI stalled out, got towed, never started again

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