Ok, I've been going through the searches for 3 hours and found a ton of great info on everything except my issue.

Just to get some other opinions on this I wanted to post in case I may be missing something. I'm very familiar with SBC's in general but this is /was my only TBI car so I want to verify. I know it's annoying when people don't give enough details and I thought that the post might help others considering all of the No Start Posts I saw tonight so....

The short version:

1988 Formula 305 L03 TBI - 124K miles

Was running fine, New Plugs, wires cap rotor (about 30K ago - no recent repairs etc)

I have spark,

I have fuel pressure, Fuel pump primes when Key is turned and runs fine.

The car cranks fine

The car DOES NOT HAVE the VAT's system (Thank Goodness)

A little Gas in the TBI (just to test) does not make any difference.

Starting fluid won't kick it over either - (sounds like weak spark / timing right??) - I agree.



It died in the driveway after beginning to run a little rough. At first I thought maybe the timing chain jumped a tooth because when I try to start it, it sounds exactly like a timing problem.---> Almost wants to start but not quite. But how often does jumping a tooth happen, let alone just sitting idling in the driveway.

Cranking around the balancer mark to 0 on the timing tab, the rotor is dead on #1 plug wire so I didn't jump a tooth (I am ready for a chain though).

I ohm'd out the coil and it's fine. I do have spark - see below though

All connections look fine (car was in storage so I was looking for chewed wires / mice etc) - Everything looks fine though.

I unplugged the black and tan wired timing connector. Car still sounds the same. No start.

I've checked the 4 pin connector at the ESC and swapped the ESC just in case. Same problem.

TBI Throttle blades move freely, no obstruction etc. Like I said, this thing sounds like it's just "ready to go" and then cranks quick again. When I try it again, It sounds the same. You know that "out of time / Jumped a tooth / distributor in wrong way Sound??? That how it sounds.

** in fact, I've even gotten a few back fires out of the TBI.. But ... I attributed that to simply cranking on a car that is not starting when the fuel system seems to be working fine...

What seems so simple is driving me crazy.

Here's the thing. The spark looks fine but I do think it could possibly , but not too likely be a little weak. I have the in line spark tester installed.

My question is: Has anyone had any ECM types of problems or Module problems that have symptoms like this. All of the module problems, coil issues I've had seem to be pretty straight forward.

But... that backfire and flash of fire from the TBI seems to have Timing / module written all over it....

The only thing I'm not familiar with is the TBI distributor's reluctor, module etc. Usually I'm used to not seeing a good spark with module "problems etc" but I'm still leaning toward this distributor / internals since everything else looks pretty textbook here.


To recap: My questions are:

1. Anyone had what looks to be decent spark and a "no-start" with a bad module etc. Physically everything in the distributor looks fine. No Broken Star wheel, rotor is fine etc.

2. Am I overlooking something related to a TBI car??

3. Can someone let me know if they've had an ECM problem similar to this?

Last. Since I'm not familiar with it. Could an IAC cause this??

I think I'm leaning toward the distributor's internals to begin on this and I believe I have another TBI Dizzy over here that I can try.

Again, for all of you veteran SBC and car guys in general, the best way to describe this symptom is just like you jumped a tooth etc. The sound when cranking is exactly like that. If I aligned the timing mark and saw that the rotor was off, it would have made complete sense to me. That's how much it sounds like a "physical type" of timing issue. For the older guys like me, remember what it was like when the dwell was incorrect with your old points distributors? It's kind of like the same thing.

That's why I'm wondering if it's a module type of thing.

Hope all that makes sense. Give me your input, I know I'm obviously missing something. No rush, the car is a project not a daily driver. (It's just now blocking my driveway...

I'll update the post if I've missed anything.

 

Put a timing light on it.
At *any* RPM below about 400, it's running strictly on the module in the distributor, and will be what the tag says for the disconnected wire test.
Seen those symptoms with any of : bad coil, bad wires, tracked cap, failing module, fouled plugs, and ( silly me ) getting the plug wires one off at the cap.

 

Timing light isn't exactly going to be a huge help on a car that isn't starting. (Plus I already have decent spark) so it would obviously flash during cranking but wouldn't tell me much more than that.

Like I mentioned, It does seem like the module to me but I've never really had those symptoms exactly like that before. On all of the regular HEI equipped cars etc, usually the modules just crapped out cold.

Just curious to see if any others have had the same symtoms. I'll be swapping the module in the next few days.

Actually... come to think of it, I believe I actually bought a module tester a few years back. I'll have to check my box here and track it down.

 

It will tell you if the spark during cranking is even remotely close to where it should be, the static "idle" setting with the test lead disconnected.
( usually between 0 and 6 BTDC )
An engine doesn't necessarily have to be running for the light to tell you when that spark is occurring.

 

You might be fighting couple of problems..

Check all ECM grounds (back of passenger cylinder and by thermostat) - clean them thoroughly. Pull codes, if any.
Verify TB injector coil resistance - should be around 16 Ohms.
Check and see if ECM is firing injectors - use a test light, see if you are getting blinking on blue or green wires feeding injectors (red should be +12 at all the time).

On ignition side
Check reluctor coil in your dizzy - it should be between 500 and 1500 Ohms.
Verify that magnet dust ring is intact and all magnets are still in place! We had a post while back missing perm magnet (due to the use of hammer) caused bad starts and rough idle.

//RF

 

Cflick, as I read over the thread again, I just wanted to mention - Don't take my last reply the wrong way. I appreciate the info. It's just that I already have confirmed that I have good spark and "physically" have confirmed that I'm at 0 degrees. Even if I had someone cranking the car, the single flash when the timing mark came around would simply verify what I already know. (Unless I'm somehow missing what you're trying to say there).

In my experience, trying to crank an non starting car and watching for a timing light flash on the balancer mark to verify static timing always seems a bit difficult compared to just manually turning the balancer to TDC of the compression stroke, verifying that the rotor is on number 1 and then disconnecting the black and tan lead. With good spark already verified, I'm able to see exactly when the cylinder is firing with the spark tester inline,.

Again, Sorry if I'm missing what you are saying. Comments from others are a huge help since often you can get really "involved" and blinded and off track. Your way certainly does work and is very effective especially if you don't get a flash. My point of view has always been that a timing light will usually flash with even a weak spark where my Snap-On test light will be very dull when spark is weak... bright when spark is good and "off" when there is no spark. Thanks for the comments.

RF master, You pretty much hit on what I was thinking. (And I did find my module tester adn I'm checking to see if it will test the internals of the TBI distributor).

The ground I did not think of and I'm going to check that especially since the car has been in storage for about 4 years now.

I did verify with my noid light the TBI Pulses and everything is fine in regard to that. I'v got about 15.8 ohms on the coils with the Fluke DVM.

I did not check the reluctor coil as of yet or look in the manual so thanks for the info on the resistance. The magnets and dust ring did not occur to me as I have'nt taken a look in there as of yet. Thanks for that as well.

I really think It will come down to a module but I was just curious as to operation of the system. I've been so tied up into my Jag XJ-S V-12 Bosch Fuel Injection and some of the other foreign cars I have as toys, I'm just drawing a blank on something as straight forward as the GM HEI type of system. It's been too long :

Thanks both for the comments. They are much appreciated. That's what's great about the boards. Always someone who has had the same issues. It's a real time saver. Especially when It's cold outside...

 

I had a similar problem with my '95 CPI Jimmy.She had fuel and would turn over but not start.The pickup coil was the culprit of that.On my '83 CFI Z28 she would turn over but not start.Went thru everything and found an open fusible link in the feed from the battery to the oil pressure switch.Just another line of thought if your ignition tests don't solve the problem.

 

It takes a bit more than something that I might read different than it sounded when you wrote it. ( how do I know that ? ) Fuggedaboutit

First, since you've already tried gas and starting fluid directly in the TBI, I'd ignore fueling ( injectors, pump, ECM, etc ) until it'll fire on that. If it won't fire on fuel directly into the TBI, it won't matter if the ECM works or not, yet.

An inductive pick up light will tell you that a spark has actually occurred, OR the plug is so hopelessly fouled ( shorted ) that it doesn't matter. It seemed a bit of an obvious thing to miss considering everything else you've tried. The other methods will generally tell you that some voltage appeared, but not that actual spark current has flowed through the plug. Matters not if it's weak as once the mix is lit, it's lit. Yeah, it matters at high RPM, but not so much now.
You didn't say that it sputters and stops, but that it doesn't fire at all, or at least I think that's what I read, so any spark at all will do something at cranking speeds.
I, too, have "physically" set the dist, only to have the light verify that it was 8 ATDC. That particular mill would run there after it was already running, but would not start there. Lining up the little arrows on the reluctor *will* get you in the ball park, usually "close enough" but not always. ( how do I know that ? )
Worst case, an inductive light will confirm your methodology.
Next, I'd check whether or not there's a possibility the damper has slipped. If it has, then both methods will produce the same wrong result.
I've seen a bad coil test fine staticly, but fail to spark, and fail to consistently flash the inductive light clamped on the coil wire. No start, but ran fine if/once it did start. ( and a nice consistent flash when running )
I'm sure you know as well as I do, if an engine has fuel ( which you poured down the TBI ) has compression ( air and seated valves ) and has a properly timed spark, then it MUST fire. It really has no choice.
If you pour fuel in the TBI, you can completely disconnect the ECM, and yet the engine MUST fire ! Won't run long, but it will start. The timing built into the dist module will run the engine by itself. The advance will be different ( there is some built into the module. Usually kicks in about 1600 or so ) but it will run. That's why *I* wouldn't bother with injectors, ECM, etc. at this point.
I'm with you. It's likely an ignition problem, but if it has a good consistent flash, I wouldn't worry about the coil, module, reluctor, etc. and look hard for a timing error. Inconsistent flash, then yes, reluctor, pickup, coil, etc.
If you can confirm that spark is consistently occurring on the correct cylinder within a degree or two of where it belongs, then I'd clamp the inductive light on ONE of the injector wires. Same theory. It's the actual current that does the work that also lights the light, not the voltage that may or may not be present.
If that works, shine that same light in the TBI and look at the fuel spray pattern.
But, pouring gas in tends to put fuel delivery in the "doesn't matter" category for now.
Now, had you said you poured in a whole quart........

 

I'm going to mention some really simple (and may seem stupid) things - why? Because usually the best answer is the stupidest one (in my world anyway).

1) There should be a fuse, close to the pass. fenderwell, where the battery is (in that general area) - make sure it's not blown.

2) Double check and make sure plug wires are in correct order on the cap.

3) Check the continuity on each plug wire - I've often gotten brand new wires with breaks in them.

4) Make sure all plug wires are securely on plugs - I had one that would come off on it's own and I had to slightly crimp the end to make it fit tighter on the plug.

5) Try replacing the Spark Module in the distributor - it was about $28 last time I got one from Autozone/Advance.

Good Luck!

 

Thanks again for the tips guys.

I'm going to shoot for the module first. It's where I was leaning and it seems like others have had the same issues. In fact, I have an entire TBI Distributor here that I can to a quick swap to check. And ... it looks like this module tester I bought a few years back will test the OEM module which is good.

I'll also check the fuse mentioned. I would imagine it should be fine since I seem to have decent spark etc. It's worth a look though. Wires are correct on the cap since the car has run like a dream right up until it died like that.

I'll post my results.

 

So, I re-read this whole thing again.
Got a paperclip ? What codes ( if any ) are being reported by the ECM ?
Also, that bit about the rotor pointing "dead on" seems wrong. Should be a few degrees ( maybe 10 ) behind it, as there is no mechanical advance in these dist.
Could be OK, just strikes me as a little off.
Backfire says it's got fuel, and spark. Not a whole lot left.

 

Ok,

Like I thought (and as most of you thought), It was the module. In fact....The reason it's the module....????

The gasket (apparently) under the factory Formula hood (rear piece of the "bump") must be leaking just a bit. It aligns perfectly with the distributor below. In fact, it aligns so perfectly, water drips right at the spot where the connectors exit the distributor. It's obviously happened in the past.

It's not exactly an "air tight" fit where the cap is molded over the plastic piece where the wires exit. Upon closer inspection, I can actually see where water has dried up inside the distributor right along the module.

This could seem to make sense since the car has been in inside storage for over 4 years and the first time it sits outside a few days, this happens.

or.....

The module just could have crapped out. But with the obvious water droplets on the top of the cap (it rained last night) and the water mark along the module, I'd say this could be common as these cars get older. (at least the ones with the Formula Hoods).

Thanks for all of the input. I just wasn't sure if this could possibly be an ECM type of issue. The symptoms just were a bit strange on this one.