Abubaca

iTrader: (3)

Let me get back to basics here. I have spark, and presumably I have fuel. Although I can't swear the injectors are actually firing, I can't imagine ALL the injectors having coordinated intermittent failure. ....but maybe, who knows.

Does anyone actually think maybe the injectors aren't firing for some reason??

...I'm just grasping here...

JP86SS

iTrader: (1)

If the TPS is >80% (or something in that range) during cranking then you will not get fuel because the fuel is cutoff to clear flooding. (Yes, to your question if you can flood it)
Might want to check that you are getting an intermittant high reading out of there.
Other than that just to have something else, check out if you have pressure in the fuel tank when you find it won't start.
See if taking the cap off vents pressure or sucks air in.
Might give a clue.

John Millican

iTrader: (1)

Have you changed the ignition module like we talked about in the other thread?

3.8TransAM

U know,

thinking about fun I have had, try this one.

Next time it was running and then doesnt start, stick your nose up under the column and sniff around.

I had an ignition switch that did this and I found it when it would let smoke out.

Car would intermittently not start hot and it got worse and would actually make it stall after so long. I would carry my meter and start checking things and always find good voltage, eventually it dies completely and I smelled it letting the smoke out :-)

Car would stall or not start hot and everything would test ok, the switch just couldnt take the load while the car was running and overheat.

Something dumb too think about , u said 170k, it aint no spring chicken

later
Jeremy

Abubaca

iTrader: (3)

New thought.

...and I really appreciate the responses. I've read through this thread a hundred times. Thanks.

I'm dealing with a tranny issue where the the car seems to not want to accelerate at around 2500, and it feels generally slower. I'm wondering if maybe it's not the tranny, but something with a sensor or some wiring that's just not jiving with the computer. First was no starts, and now I'm having issues with fuel (possibly) while running. It doesn't shut off, and it'll rev fine in neutral/park, but under load I'm having issues. Maybe they're related?

Kinda like weak spark? Although my spark checks out fine. Maybe a drain in the electrical system? Everything seems fine, the gauge, the lights, and the battery tests fine. Maybe something else?

I dunno.

...just another thought.

dyeager535

Well, I'm back too.

Went out and started the thing not 30 minutes ago, first time in a week. Let it warm up to operating temp, start backing it out into the street (rolling, not under power) and it dies like the key was turned off. Check engine light is on, high MAF code. Start it, drive it back into driveway. Check TPS, it's a bit low (.50V) so I figure thats the issue. Pull ECM fuse, make sure code is clear, go to re-start.

Nothing. Doesn't even attempt to fire.

I started out on the diagnostic chart. Problem 1, the scanner has never shown cranking RPM while the engine is attempting to start. So I don't know which path to go down. No biggie, I try both ways.

Have spark. Pull distributor lead, touch to 12 volts (supposed to indicate RPM on scanner) it doesn't show any RPM. Not a big deal, I figure that has something to do with the scanner not reading cranking RPM in the first place. CKT 430 is checked (module to ECM) and there is nothing wrong with it. Since the dash is apart, swap in spare known good '165, stock PROM. No dice, won't start.

Go down other side of chart, check for blinking light during cranking. No blinking light. ECM doesn't know/can't fire injectors. Check both injector leads with test light, both have voltage with key on, which is correct.

So...if I could trust my scanner to show RPM when it should, I'd know for sure which path to go down. In any case, it looks to me like the ignition module, especially the circumstances that it happens.

Dan8289gta

Ok i have been down this road more than once and know exactly what you are dealing with. #1 if you are getting spark you can rule out your ignition module, a bad module will cause no spark and no injector pulse. #2 CHECK THE RESISTANCE ON YOUR INJECTORS, in some cases even 1 bad will prevent all 8 from firing properly the car will crank and not even attempt to fire. Its very easy to do get a volt/ohm meter unplug each injector 1 at a time touch the two leads in the injector they should read 16-17 ohms anything under 10 is unusable. If you do have a bad injector and get it to run or keep trying to make it run you will fry the ecm in time.

3.8TransAM

Anything to do with the fuel pump?

Ones that give up the ghost slow tend to it 25-3000rpm where fuel demand is highest due to torque.

Have u checked the grds on the back of the cyl heads yet also?

later
Jeremy

dyeager535

The problem for me at least is now 100% repeatable. Engine gets anywhere near operating temp, not even driving it, just sitting in the driveway, turn it off, try to restart, nothing.

Once or twice I've got it to sputter for just a split second, then back to crank with no injector firings.

Since I like knowing how to test stuff, I followed the procedure for testing the coil, which actually showed the coil has failed. I need to test cold vs. hot though, just to verify my results as I only tested once. When it's cold though, it will fire right back up.

I just "upgraded" to $6E/APYP and modified the injector firing/crank pulse for startup, and it starts VERY quick, which is great. But only when cold. Once I know it's not going to start, I've tried varying amounts of throttle just to see what happens, but it's obvious that doesn't change things.

Fuel pump I highly doubt in my case. It's new, which doesn't mean anything (as is the filter) but as long as the truck isn't shut off, it runs excellent no matter the RPM/length of time/temperature of engine. I've got fuel pressure whether the engine is hot or cold.

I swapped the module with an unknown condition one simply because I felt like doing something and I hadn't swapped one before. Not to mention that even if I took it in to be tested, it wouldn't be tested under engine compartment temps. Interestingly, the "fail bubble" (yellow plastic on the original) on the module I took out was up, while the white bubble on the unknown condition was still flush. Of course, that unknown condition module caused the hot start problem to change from somewhat consistent to 100% consistent.

Injectors all show 16-17 ohms except two@ 13. With two off by that much, I plan on getting new injectors in the near future in any case.

With all the components being almost 20 years old now, (besides the issues that are already present) I figure it's preventive maintenance to replace the coil/module/pickup while I can still get Delco stuff.

I'm sure it's the module(s), but still going to test the coil and pickup to make sure they are worth keeping as spares.

Dan8289gta

I have had a computer fail in the past that would shut down the car once warm, also had another one go south when it did it would not advance the timing from base 6 degrees so the car had no get up and go and topped out about 40 mph, I did get a ses light that time though. Just some food for thought.

dyeager535

Yep, swapped ECM's as well while the problem was present, (known good ECM) and did the whole PROM burn deal as well, from $32 to $6E and back with the old PROM.

No trouble code of course, that would make it too easy.

Dan8289gta

Arent our cars a blast to trouble shoot

Lucid

iTrader: (4)

Abubaca
Does the volt meter on the dash register a drop in voltage when you are driving? Do you have access to a scanner? The cool thing about a scanner is that you can watch the sensors and how the ECM is responding to the readings. (autozone may let you borrow theirs, my friend let me before i bought one.)
If it is one of the sensors im leaning towards the coolant temp or tps. Check and make sure that TPS is at around .54 Volts at idle with the engine off/ignition on and that it has a smooth transition from idle to WOT either by resistance test or by taking a voltage test. Its interesting that you dont have any codes, is your SES light working?
It might also be helpful for you to get some wiring diagrams of your car. I went to the library and photocopied from those big books all the diagrams that were pertaining to the ECM and its components. I will take a look at them when i can find them and look up all the components that are tied to the injectors/fuel pump etc etc. Before you turn the key on next time, make sure the radio is off, and the a/c blower is off, turn the key and listen for that click and fuel pump whine when it primes. (should whine for about 3 seconds).

Abubaca

iTrader: (3)

Just from reading and comparing my experience, I'm leaning towards pick-up coil.

...I have NOT tested the sensors yet
...I have NOT tested the injectors.
...I'm swapping injectors regardless, after 170,000 why not.
...voltage acording to the gauge is fine
...fuel pressure at the rail is perfect under all conditions

...I've been saving for a house and just haven't worked on the car much in the last few weeks.

...I'll certainly report all finds once I get back to wrenchin'!

CrimsonDragon

Abubaca, I have an 89 IROC that has had the EXACT problem from multiple sources, repeatedly not re-starting for years. I went to many different mechanics and eventually found an automotive electrical specialist that tracked down the problems. The first time I had a restart problem it was the resistor that went bad in my key. The second time I had a restart problem it was the sender for the VATS that was going out. At the time, I had a Chapman alarm and the auto alarm company assumed it was the starter kill that went bad and we replaced it with a Viper. Ended up not needing it but the Viper is a better alarm. Interestingly enough, when the Vats sender went out, the alarm guys tried to hotwire it and even their best guy couldn't get it started. The auto electrician ended up by-passing the VATS sender, exactly how I do not know. Now the third time is do to the original Injectors failing and I am in the process of replacing them with Bosch 22# injectors. I ended up causing myself some problems by putting in Fuel Injection cleaner. Multec injectors have some wacky tendencies while they are failing. For expert info, give Rich a call at Cruizin Performance (231) 796-5705 , he will illuminate you on the ugliness that is Multec. He is a great guy and if it isn't the injectors now giving you problems, they will because as Rich said "It is not a matter of "if" but "when" . He recommends the Bosch injectors and to stay away from Fuel Injector cleaner as it has both good and bad properties. Lastly, I have had re-start problems SO MANY TIMES! and it is very frustrating and at times embarrasing so I understand what you are going through all too well. I went around and around tracking mine down and it sounds like yours is VATS connected. Good Luck and let me know what happened.-Mike

Brisk

iTrader: (25)

Abubaca - if do you a search you will see I had the EXACT same problems.. occassionally won't start, then got more frequent. Would always start when cold or after it sat for a while. Like you, I too, tried testing, replacing, metering everything... (sorry I didn't read the whole thread)

Till one day it didn't start at all (after a year). Fuel pressure always tested good, till the last time. However the culprit, all along, was the fuel pump.

Oddly, I can't explain it, but I'll try. I removed the fuel pump and prepared the replacement. However when I started assembling the a new pump, to replace the old one, I was removing the reusable parts (hoses, float, etc) and found one hose was under pressure. When I pulled the hose off the old fuel pump it sounded like opening a bottle of beer or something. Very unusual.

I couldn't duplicate it again, and oddly enough, the pump I removed worked everytime when bench testing.

It is a big job to replace the fuel pump, but I would certinally start there, especially if it is still the original. BTW, my experiences are from an '88 IROC w/o vats.

Abubaca

iTrader: (3)

Well I found the problem. It was the distributor itself.

.....The problem was happening so infrequently that I didn't actually inspect the distributor during the rebuild. Even if I had, I'm not sure what I would've found. Anyhow, shortly after the rebuild, I added an MSD6a box and coil. From what I've read, this can and will find the weak link and kill it. When I pulled it out to replace it (I was gonna do it regardless) I noticed just how bad it was. I don't know the proper term, but the eight "points" under the rotor were almost completely gone. (it's not "points" ignition, but you know what I mean). Anyhow, I'm surprised it stayed running. But if you remember, the last few months I was losing power and it was almost to the point of not driving it anymore.

Does this mean it was the ONLY problem? No. Heck, there could and probably ARE more problems, but for now she seems to be OK!!!

CrimsonDragon

Congrats!! Glad you found it and it was a relatively simple fix!

Lucid

iTrader: (4)

Good to hear a happy ending.... Are you talking about the distributor tabs in the distributor cap?

Brisk

iTrader: (25)

well I for one am surprised.. I'm going to check my distributor cap tomorrow

dyeager535

Well, I figured out my no-start when hot condition.

It's a wiring issue of some sort. Since the problem is consistent now, I was able to start troubleshooting.

Long story short, if I power the injector feeds directly from the battery, the vehicle will start every time. If I let it run the normal path from the fuse panel, it will never start when hot. 100% of the time if it sits overnight, it will start (only) on the first attempt.

There is apparently JUST enough voltage loss through the ignition wiring to keep it from starting after being started once. It's not much, I measure less than .5V loss from batt to injector feeds, but it's enough. It appears that as engine temp rises, likelihood of a no-start increases, which makes sense. Kind of odd though, since it doesn't take but 100* or so before the problem starts.

Just thought I'd let everyone know that I figured out essentially what is causing mine, now to fix it!

rgarcia63

That indicates a loose connection, or corrosion at connection(s,) most likely at the battery, alternator, and starter.

dyeager535

As the fuse panel gets voltage after all three of those components, and feeding battery voltage to the fuse panel lead (bypassing all of those components) doesn't solve the problem, how do you figure it's a bad connection at one of those?

I appreciate the advice, believe me, I just believe I've eliminated anything before the ignition switch/fuse panel lead. If I'm missing something I'm more than happy to hear it.

rgarcia63

IF, "If I let it run the normal path from the fuse panel, it will never start when hot," and, "feeding battery voltage to the fuse panel lead" means that regardless of the voltage source to the fuse panel the problem remains then there's no bad connections up to the fuse panel.

The fuse panel "Lead" comes from a "hot at all times" junction fed by a fusible link to the battery, but does not feed the injectors fuses directly, that junction also feeds the ignition switch which in turn feeds the injectors fuses.
Try jumpering a "hot at all times" fuse panel source to the pink wire at the ignition switch then, to the ignition side of the injector fuses (other end of pink wire at the fuse panel,) then the injector side of the fuses..., and so on until the engine starts as it should, hopefully it's the ignition switch, or it's connector, good luck!!

Virtualdemo

Whew! Lots of reading...

Have had this problem with most all of the external HEI systems. When your car(s) dont want to start, take something/anything and tap on the ignition control module. TAP dont knock the hell out of it...lol I have had this problem 3 out of 3 vehicles. I got to the point that I didnt change the modules anymore, just tap and vroom, take off....lol I see this a bunch more times than I care to. If I see a GM with the hood up and talk to whoever is around the car, tell them the lil trick and they look at me like im stupid...

But try this out, no money involved and it very well might be the problem you all are having.

Lates,

Demo

Almost forgot to add: New modules dont mean squat, I have had to go thru quite a few till one actually lasts. Wish I knew what exactly was burning out the modules in the first place...

rgarcia63

You'd have to remove the dizzy cap to do that. you've been lucky, I've never had an intermittent ICM, once it fails it never works again, and as a last resort I have tapped them, but it hasn't worked for me.
I guess I've also been lucky I've never had a DIB ICM (dead in the box.)

Virtualdemo

No need to remove the cap. Just tap where the two connectors go into the module. Strange how you havent had any luck with it. I guess I "scare" em into working...lol

A lil off topic, I picked up a S10 Blazer for about 300 bucks due to the owner not finding the problem. Tapped the module and drove her off....lol Great thing was he replaced almost every electronic thing on the blazer. Its still on the road and now has around 285k miles on it....woohooo

Anyways, its probably not the problem but its a good start and its free...

rgarcia63

Must be really dry air in LaU, NM

Virtualdemo

Am I mistaken or dont 87 + GM vehicles have the external coil? And arent these called HEI also? And what does dry air have to do with it? Isnt the ICM plugged into the coil? Does the ICM not control Fuel/Spark curves on start up? ICM not ECM.....Ignition Control Module. Hmmm...

JP86SS

iTrader: (1)

Spark is controlled directly by the module until about 300 rpm. Then the ECU kicks in with control.
Fuel is always under ECM control even when cranking that's why a TPS problem of full voltage can keep it from starting.

JoeSmiteGTA

Hopefully this post isn't too old to bring back..

I too just recently had this problem. Like never had it before and then every blue moon it wouldn't start. Wait 15 minutes and it would start. But most recently I was driving along and during deceleration (leaving it in gear but no gas) I would get a stutter and next time I would put the clutch in, it would stall. I could keep it alive with the gas, but it was a losing battle. After it stalled I could turn the key, it would start just enough to turn over once and then stall. Twice. On the third try it would keep running for a few more seconds.

I eventually got the car to a friends house where it sat for a week or so. Would crank forever but just wouldnt turn over. My father and I checked some vacuum lines and replaced the cap and rotor (seems my car is running a bit retarded, I didn't know that), and it started right up. No problems whatsoever. Until two days later. Dead. Crank and crank, nothing. I got it to start once, and it would die every time I hit the gas. I figured I may be the TPS because the pedal directly effected the problem. Replaced it and no change. Also replaced the Ignition Module.

I've read this thread and this problem seems to have so many causes, I just don't want to be throwing money at it if I don't have to. I considered the ECM being bad because I had attempted burning proms at one time and only changed the injector size, but there is a custom prom in it. Also, I had an amp and sub in the car for a while, and it always had a popping and cracking problem no matter what I tried to do. I mention that because I don't know if it is somethign electrical or not.

I'm stuck because this is my only vehicle and it sucks because its just sitting and I don't know how to fix it. And when I do, I'm scared that it might happen again. I'm trying to decide if I should take the money I'm trying to save to fix this thing on buying a cheap daily driver. That would keep this sitting longer though.

I'm going to read through the thread again and double check everything. I'm in Fort Lauderdale, FL if anyone is nearby and wants to help somehow. Thanks in advanced.

EDIT: I forgot to mention, checked spark from the coil and then checked spark from a plug. Both seemed ok. Also replaced the fuel filter.

Johfer

Time for a proper revive of an old thread. And actually hi-jacking it a bit.
My first post here and hoping to use a bit of all your experience since there is less to be found here in Sweden.

I have 5.7 TPI in a 1988 firebird with 68000KM on the meter that have issues close to these above.

If i run the car it works fine, starts fine again even when hot WITHIN 2 minutes after turning it of.
But after that it’s hard to start, it fires up if i put my foot to the pedal but has no idle. If I keep it running for 30 sec turns if of and then restart all is back to normal.

It’s the same if its 5 min after running or a week in the garage.

Strangely if i start it cold and run for a while and then let it sit the issue doesn’t show.

My thougts are going towards a vapor lock in the fuel rail but cant figure out how?

Fuelpressure is ok
Returnline to tank ok
Fuelfilter changed
Injectors tick not yet measured.


I also feel a lack of the power that i think should be.

Thoughts i have had i FPR rebuild/upgrade.