CheezeIt305

Good afternoon everyone. I usually get some good advice from this forum but this time I messed up big time lol. My 89 Firebird with the 5.0 TBI cranks but won't start after I replaced the IACV valve. This whole thing started about a month ago. Since I got the car it had been running perfectly fine, except for starting. I would always need to give it some gas to get it going for it to start but afterwards it ran fine. Well, since the winter started here in Chicago I let it sit for about a month and a half to avoid driving in the salt. When the weather got nice enough to drive it, it had a really rough idle between 500-1000 on startup which had never happened before. Sometimes it would die and other times it would run fine again, when I looked up if anyone had a similar issue on here it was suggested that the IACV valve be replaced. Well today I replaced said valve and the car was running great. It even cranked right away without needing gas. I drove it for a bit and it ran like a dream until suddenly it started stuttering a little bit on idle. Being the genius that I am I figured I wanted to test the alternator at Autozone to see if maybe the stutters were an electrical issue, the guy couldn't hook up the clamps for some reason and the car then would not crank at all when it was time to do the starting test. I figured maybe the connector to the IACV valve may have gotten loose so I disconnected and connected it again and the car cranked like normal but was back to stuttering like crazy at idle. I got it home and installed the old IACV but this time it would just crank and not start. I reinstalled the new one and it was the same thing. I don't know what could of happened during the test drive for it to do this. Any pointers or suggestions? Its worth pointing out that the negative cable was loose when the Autozone guy was fumbling around with it so when I got it back home I tightened it and the multi meter read 12.4. I hooked up my jumper to it and it still wouldn't crank.

Schurkey

1. Fully charge the battery, assure that the battery cables are clean, tight, not corroded internally or externally. 12.4 is way too discharged.

2. Connect a scan tool, verify ALL sensors, computer outputs. Check fuel trims, spark advance, etc. Make sure the IAC can maintain commanded idle speed.

3. Verify fuel pressure including prime cycle.

4. Testing components "off the car"--battery, alternator, starter, etc., is better than nothing but absolutely second-rate. Third rate if the pimply-faced kid behind the counter hasn't been FULLY trained to use The Machine that does the actual testing.

5. How old are the usual "tune up" items/procedures? Cap, rotor, plug wires, spark plugs, air and fuel filters, PCV valve. When was the initial timing checked? Will the coil produce a strong enough spark to jump the gap of a proper spark-tester calibrated for HEI when the coil is hot from being used for twenty minutes?

CheezeIt305

Thanks for the reply! Today I inspected the battery and sure enough the terminals are loose. The terminal post bolts are too fat to fit through the terminal wire because of the rubber housing and they ended up stripping out the battery when trying to catch onto the threads. Thankfully I have the autozone warranty thing and the same kid that fumbled with the tester ended up swapping out the battery for free lol. Anyway, I bought two new terminal bolts just in case and installed the battery. This time the car caught when cranking but didn't start and instead just stalled. I tried cranking it again and it didnt catch and it started smelling of gas. Multimeter read 12.4 again so i threw on the battery tender and called it a night. To answer your question, all of the tune up items are all stock The original owner rarely drove it and the car has only had basic maintenance and emission work done to it throughout it's life. It's also been garage kept for most of its life. Tomorrow I'm swapping out all plugs and wires since they're due to be swapped out anyway and I feel like the motor might be flooded from how many times its been cranked already. I haven't checked timing or fuel pressure so I'll ask my buddy who's more familiar with these older systems if he can help me out with that. I will keep posting updates as to not lead someone to a dead end like some of the other posts regarding crank no start

CheezeIt305

Update: From past experience with my 94 Dakota, I replaced the ignition coil as it was acting the same exact way. No luck. We tested for spark on Cyl#1 and got spark. Tested ground straps on the back by the firewall and the one by the battery and both had conductivity when tested with a multimeter, that rules out a bad ground. When cranking the car we heard the injectors clicking and saw fuel being sprayed into the throttle body, checked oil and it smells of gas from cranking so much. It did not smell like gas when i checked it a day before this mess started. Today we're replacing all of the plugs and wires and checking the cap and rotor. If this doesn't work we'll test timing. Things worth noting, it doesn't start with starting fluid and before this crank and no start crap, it was idling really rough when starting it. The car would idle at 1000 and dip to 500 like it wanted to die. After it would get to temp it would run fin and idle good. I replaced the IAC sensor and it ran perfect. No more bad idle and it even started without giving it a little gas. Well that only lasted for 30 minutes before it started to idle rough again, at which point it started idling at 1700 rpm. I turned off the car on and off twice and it would stay stuck at 1700. When the autozone kid tested the battery the car would NOT start. When I turned the key the starter wouldn't even engage but the lights would dim. Finally after tightening the negative post and wiggling the IAC sensor and using a jumper, the car started. Drove it home, parked it in the garage and afterwards it would not start but does crank which is where I'm at now. Would any of this be related to why it doesnt start??? Anyone have any ideas?

CheezeIt305

UPDATE: Problem has been found. Timing and distributor are good. We noticed that the fuel injectors were dumping a crazy amount of fluid into the throttle body. Tested both injectors using a 9v battery and heard clicking. We then cranked the car with the injectors disconnected and it started right up and ran for a bit without them but it would go back to no crank with them on. Any pointers on where to go next? Could it be the ECM or fuel pump?

Schurkey

Failed sensor(s) or wiring can cause massive fuel dumping via the injectors. A disconnected/rotted/broken harness from the coolant temp sensor, for example. The computer thinks it is -40 and provides huge amounts of fuel.

If the fuel pressure is too high, too much fuel might be dispensed from the injectors.

vinny R

Check your TPS also.
You said the PO didn't drive much and the car sat in a garage when not used. The injectors could have gotten messed up from fuel sitting in them for too long. Not sure if you can service those TPI injectors or not.

CheezeIt305

There's scan tools that read OBD1? Or do you mean looking at a scope using a scan tool? I'm sorry I'm really unfamiliar with this side of repair and so is my friend. I'm starting from zero on the scan tool, what would you recommend I do as a beginner? And where could I get a scan tool? As for testing fuel pressure, we could probably manage that. I did order the OBD1 plug thing to at least see what codes the computer throws

Tuned Performance

iTrader: (92)

If you have codes, just use a paper clip and blink them.

CheezeIt305

Only got code 12

CheezeIt305

UPDATE! Car is now fixed and running better than before. It ended up being the coolant temp sensor that was dumping enough gas in the TBI to create the crank no start from flooding it. Thank you Schurkey and user Casey Butt lol. I'm guessing the old IAC was giving it enough air to sustain the amount of fuel it was spraying from before as the car had always idled high. I guess that day at Autozone the sensor completely failed and was giving it the -40 reading to the computer which caused the 1700 RPM. The starter not engaging was from the AutoZone kid finally stripping off the last remaining threads on the battery bolt.

Tuned Performance

iTrader: (92)

no code 15 ?

Schurkey

Of course. How do you think these vehicles were fixed when they were new?

I have an extensive description of a REAL (but obsolete) scan tool's capabilities when used on an '88 K1500. Other tools may have somewhat different features/abilities, but the real limiting factor is the sophistication of the on-board computer itself.

Posts 14 and 15, but the whole thread is kinda humorous.
https://www.automotiveforums.com/vbu....php?t=1146067

CheezeIt305

No. I waited for code 12 to flash 3 times until the rest flashed. Nothing ever came up but code 12.