I have a 1988 305 TBI Firebird
I tried starting the car yesterday, it just turned over and over. Finaly I got it started, but it ran horribly until it started warming up. I was pumping the gas a little so it probly flooded a wee bit as I was trying to start it. When it finaly started, it shot out a bunch of black smoke.
I go to start it today and same thing happens only it will not run even with a little puming. I pumped too much and now have fuel coming out of my header collector gaskets. Some probly got in with the oil, but I need to change it anyway(it's due). I was able to unplug the injector wires, so that they would not fire. After doing that, I tried starting it up and it ran for a little while on the gas that was still in the cylinders. I guess I don't pump it anymore then
Well, my only question I have is...What could the problem be? Are there any sensors that could be bad and would cause this problem? So, it starts as long as there is no gas going through the injectors. Sounds kind of funny to me. I currently have the throttle jammed open so the intake manifold with dry out a little. There are puddles of gas in there from my stupid attempt to start the darn thing.
After getting the thing started last night, it kept starting as long as the engine was warm. So, if I let it sit for more than an hour, it would not start. I thought it could be with the electrical, but since it ran on the gas that was still in the engine, it probly isn't that.
The past few days, I have had to really crank it to get it to start up. I am having a feeling there is something wrong with the fuel so that it is not getting enough on startup, but it finaly is able to start after a few cranks. I normaly can get it on the firstshort try, but now I need to hold it for a second or two.
I know there isn't much information in here.

 

Your CTS sensor could be bad. Also, trying putting the pedal to the floor while cranking the engine. I have to get back to work, I know there are other things.

 

What and where is a CTS sensor and what does it do? Does it effect how the car starts?

 

Coolant Temperature Sensor. It measures the temperature of the coolant . The ECU uses this measurement in determining fuel delivery. If it was broken/disconnected it would read an insanely low temperature and the ECU would deliver an insane amount of fuel. Somebody correct me if I'm wrong, but if memory serves me correctly, I believe the CTS screws into the coolant passage on the front of the intake manifold.

 

Ok, so if this is going bad, how would I be able to check it? have the car checked with a diagnostic program or whatever they do? I don't wan to get a whole new one if it's not even bad. I got it started after it had been sitting in the sun a little while today. I also got some of the gas evaporated out of the intake manifold. I'm going to wait until it cools down again to see if the problem remains.
I had the air filter off when I finaly got it started and it looked like the normal startup amount. It still seems like alot though. The gas kind of puddles up on the throttle blades because they are not open all the way. Is that common?
Also, is there any way to determine how much gas is being put out compared to the correct amount that there should be? It seems like I get horrible gas mileage. It's probly the O2 sensor though. Could I detect if that is ok with a dignosis as well?

 

I would go get hook it up to the computer at a garage (not the dealership) and see what they notice is wrong.

 

You wouldn't by any chance know what things should read would you?

 

You can test the CTS by splicing into it and reading the resistance values that it is sending the ECM. But that is kind of a pain. A new sensor is only about 10 bucks. You might as well go ahead and replace it. On TBI cars its a cinch. If you really want to test the sensor email me and I can send you a resistance vs. temperature chart for the sensor. irocbsa@mindspring.com
bsa

 

sounds like what happened to mine when the fuel pump was going out it wouldnt hardly start when it was cold without revving the hell out of it but if it was warm it would run just fine...it was wierd...

 

This is definatly in need of a scan tool hookup.
The values will all make sence to you since they should be converted to stuff like degree's C and kpa, TPS voltage etc.
TPS (throttle position sensor) should read near .5 volts.
CTS should be near or exactly what your in dash gauge is reading.
IAT or MAT should read whatever the air temp is, probably warmer under the hood than the actual temp outside.
The MAP should be converted to around ~40kpa at idle, wide open throttle reads closer to 100kpa.
The o2 sensor should be ignored until car is warmed up. The ecm doesn't go into closed loop until the engine reaches a certain temp so ignore the open/closed loop but understand that the o2 sensor should start working pretty fast, about 2-3 minutes after startup, even faster if you still have the air pump installed.
BLM is block learn multiplier, this value will be 128 until the engine warms up and goes into learn mode. Then if the value drops below 128 it means the ecm is removing fuel from the stock tables, value above 128 and running lean = adding fuel.
If you can, find a laptop and build the simple serial cable hookup and use winaldl. It's SO SO SO simple and if you need a premade cable let me know. The software is free so if you could get your hands on a laptop for an afternoon you'de be set.
As for the reasons why it's running rich....very long list. It could be any of the sensors not working right. It could be a mechanical problem like cam, timing chain, dissy not firing, spark plug gaps, bad plugs from bad gas, knock from faulty knock sensor, burnt plug wires not firing the plug, bad injectors, bad fuel pressure regulator. You said black smoke so that is running way rich. Do your eyes water if you stand behind the car...then it's rich.
The only other thing that might help you figure out what's wrong is that the ecm will through an error code if the sensors are bad or not working. That's if they actually break, if they are just going bad then it might be near impossible to tell without a scan tool.

 

Hey!!! I got it started. But that was because it got past 60 here today. I'm going to get up early in the morning when it is cold and give it a shot. I doubt it's the fuel pump going bad. The previous owner told me it had been recently replaced. That was a little more than 2 years ago. I don't think that could be it. I could go through and check all the past reciepts for any maintenance though to make sure.
Well, I had let the thing dry out a bit, crancked it a few times and it started. There was little, if any black smoke this time. There is never any black smoke when running. A puff of white on startup, but nothing major. I think there is a little gassy smell while the car is running, or after being shut off, but the cat dosn't have any air going to it. That could be a little bit of the problem. I'll try out that computer program however. If that doesn't work, I'll take it in.
Oh, one more thing.... What is that sesor on the passengers side of the TB with the spring on it? Is there any way to take that apart? It is very oily and dirty. I don't want these things making a negative difference somehow.

 

From your description I would say that's the Throttle Position Sensor. I don't know if you can/should take it apart. It probably wouldn't hurt anything though (as long as you get it back together okay).

 

Still didn't work today, so temp might have something to do with it... I don't know, probly just jumping to conclutions.
Ok... I just got a CTS this morning. Going to go put it in after this reply. I just put new plugs in a week ago and set the gap on each one to the specified .035. I have checked the wires...those are fine, I even tightened them up a bit, they could come off pretty easily. Judging by how the car starts up fine when it's warm, I don't think that could be the dist. or anything else with the ingnition. Unless it can't produce a spark when it's cold. But I don't know.
What could be wrong with the cam, or timing chain?
I don't think there is a problem with the amount of fuel being added. It may seem like a lot, but I have never really looked at it when the car is being started. I'm usualy in it and wanting to drive.
Well, I think I might be going abou this all wrong. It was very close to getting it this morning. It was sitting there just chugging like it wasn't getting enough gas. I don't know. Before I could hop in the car to give it gas....forgetting I could reach over and move the throttle by hand. (idiot) It died. I swear it was idling at less than 100 RPMs.
If the Fuel Pressure Regulator was bad, could it not deliver the right amount of fuel?
And, can the car be linked to the diagnostic scan tool wen it's not running? Then start the car while it's linked? It's probly only then that I will be able to find something. I don't know though. I'll give some more tries and get back about what I find out.

Ok....well, I'm a dumba$$. Anyway, I totaly forgot to check the trouble codes. Anyway, it turns out I had a code 54 for the fuel pump relay. I'm going to check that out.
I hoocked up that CTS sensor and tried starting it, but it didn't make a difference. I'm going to take that back and get this fuel thing I guess.

 

well, I put the new fuel pump relay in, and it didn't make a difference either. I do have one questoin though, what is the sensor that is right behind the Throttle Position one? When I have been trying to start it, there is a smoke, or vapor that is coming out of it. I don't know what is going on though. The code 54 is gone though. I cleared the code and tried starting it again before I put in the new relay, but it never came back. I think I just got a new relay and didn't need to. But, I guess I have ruled out the CTS and Fuel Pump Relay. It's not plugs, or wires. The car can run, so I think it is not getting enough fuel to start. I'm not sure though.
It was startnge how it just roared to life when I disconnected the injector plugs on the injectors. It started as easily as it normally does.
This problem is crazy. Well, I know an automotive teacher at the local college. I'm going to talk to him about this since he lives close and knows mor than I do about this.
I put the car on a computer diagnostic program and the values I got were exactly the same as teh ones JPrevost said they should be except for the TPS. That was at 7.5V The CTS and IAT were about 2 degrees off. That was using hte old sensor, so those are good. The only thing left to be wrong are either the injectors, fuel pump(I doubt) or the fuel pressure regulator.
It's crazy how you jack up the car to tighten header bolts, lower it, and the car doesn't start again. It can only happen to me.

 

Ok, this mother $&%($*% TB is not working again. Something in my car is screwed up. I had a post going abou tfixing this problem. Well, after changing many parts, I finaly rebuilt the fuel pressure regulator. That solved the problem for 2 days. I don't think $60 is worth 2 days. I am beginning to think that the problem doesn't lie with the regulator now. But I don't see how the rebuild solved the problem for 2 days. I guess the car doesn't start in the cold anymore. I am going to college now, so I only drive the car on teh weekends. I am just glad I don't have to get anywhere important because I could never get there Here is a list of everything I have changed. I think the car is running way to rich to even start.
Fuel Pressure Regulator Rebuild Kit
Fuel Pump Relay
CTS
IAT
New Fuel Pump and filter(1/12/00)

I have ran the car on a diagnostic software and everything appears normal to me. I cannot tell what is wrong.
If there were too much fuel pressure, could it actualy outflow the return line back to the tank? It seems very unlikely since it is so much bigger than the incoming line. This is driving me crazy. I cannot believe that a new diaphram can go bad in 2 days. It's a Borg-Warner brand. Are those any good? I'm thinking of installing a fuel pressure guage, but don't really want to spend all the money on a stock LO3. I can't see the reason for any of this stuff to be happening. Is there any other reason for the engine to be so rich it cannot even start? The car will start if it is warm because I guess it can actualy handle the extra fuel being used.

I know I have asked for all the answers here, but I don't know about anytihng else that can effect how much fuel is going into the engine.
Could dirty or bad injectos make this happen?

 

A few things that you should know about engines. They like to start with MORE fuel when cold and need less when warm. This is just a fact and I'm not going to waist time explaining the physics. Try removing the TPS sensor and starting the car, then flick the sensor with your finger slightly. You should notice that the injectors will shoot more fuel. If you can't see a lot of fuel coming out then it's a bad fuel filter, pickup, fuel line, clogged injectors. It's a simple job to check fuel pressure on both the teturn and supply lines. It takes about 15 minutes at most with a couple wrenchs. Any and every shop has the gauge and I'm sure if you can bring it to them they'll do it for like $10 or whatever. When it did run did it have a really bad hesitation/bog bad? Or did it seem to run really strong with no backfire through intake. If you were running really rich you're eyes would water in a few seconds just standing behind the car with or without a cat. My engine was running so rich once that with the cat on it melted my carpet! That's HOT HOT HOT and our eyes still watered.
If it stalls when put into gear real fast = lean. The IAC will open (causing a leaner condition) and it'll just shut off at low rpm. It's just funny how difficult it is to tell if you're running too rich or too lean. I was just talking to somebody the other day about how I was having problems and I had to make a couple eproms which I called "really rich.bin" and "really lean.bin" Turns out I was running too lean.

 

Well I've had the same problem and never been able to fix it. 84ZZ4 and I have run through all sorts of scenarios without coming to any really good conclusion, except it seems to be flooding on really cold starts.

The behavior is just what you said, on warm days, starts no problem. On cold days, cranks and cranks and cranks and when it does finally start, runs rough as hell for 15-30 seconds before it smooths out. We believe it's flooding because it smells rich as hell when it does start (ONLY for a few seconds, the problem is not a general overrich condition), and the running rough for a bit seems to correspond with what it would do after flooding, it takes a few seconds to clear all the excess fuel from the cylinders. Since you started it with the fuel injectors disconnected it sounds like you were flooded too.

I've replaced every sensor in the car without improvement. A few times there was a 1-2 day improvement like you noticed with the fuel pressure regulator, but I think it is just a combination of psychological and cooincidence... The problem (for me at least) is semi-intermittant, it happens frequently but not always.

I have NOT replaced the fuel pump. It seems hard to believe that a bad fuel pump could cause flooding (if the fuel pressure regulator is working, which mine is and yours probably is too since you rebuilt it). I did check fuel pressure and it was a nice stable 11 lbs, right in the middle of the stock range.

I also suspected it might have been getting EGR open at starting but after some diagnosis we determined that was not the problem (EGR was closed, like it should be).

The problem is, what could cause COLD flooding?

Flooding would be more of a problem when cold since fuel atomization is worse... It's possible that the injectors are flowing too much fuel or something... If they are dirty and not closing fast enough or something. I know mine don't leak if you turn the key to ON but don't start the car (that causes the fuel pump to bring the pressure up). But this is just random speculation.

 

Bad cold starts: bad CTS, or MAT/IAT, that's all that would cause a bad cold start that's too rich. Of course if you did eproms like me you can adjust the cold start air fuel ratio dependant on engine coolant temp and intake air temp
Another trick might be to use some resistors in the MAT/IAT instead of the actual sensor. If you had a switch you could just run the sensor bypass with a resistor value that makes the computer thing the air temp is warmer than reality. This could work very well if you're having problems and have replaced the sensors. Either that or e-mail me.

 

Might be a dumb, but have you checked if your injectors are leaking when its not running!! That could be causing the flooding. Am I wrong, or isn't pumping the gas pedal when you try to start it on a TBI car not necessary? The only thing it does is open up the butterflies. Anyway, you say that when it's warm it starts up fine, that may be because enough fuel hasn't leaked to make it flood. When it's cold, it probably hasn't been running for a while, so more fuel leaks. Makes sence!!
Good luck!

 

It's funny but TBI is really strange when you pump the pedal on startup. First off the ecm will add more fuel because of the pumpshot vs TPS changing so fast. It's funny that if you hold the pedal to the floor and turn the car on it goes into flood clear mode. Yes, it's an actual function of the ecm. It basically just turns the car over and doesn't fire fuel. Now I'm not sure if all of that is correct because I've never had to do it but you might want to try it and see if it helps. If it does then confirmed it's running too rich. Have you tried backing off the fuel pressure a bit?

 

I believe that in open loop (I.E. when starting the car) the computer does not look at MAT/IAT, only CTS. I've tested mine and it checked out, plus I replaced it for good measure and still no change.

Opening the throttle (partway) also allows more air in. So it may reduce the flooding (flooding being way more fuel than air)...

My injectors do not leak when the car isn't running. In fact with TBI there is no pressure on the fuel line when the car isn't running so the injectors really couldn't leak more than a tiny amount. Also I drive my car every weekday to/from work, so it sits for the same amount of time (4/5 pm to 5/6 am) no matter what the temperature is out.

One thing I have NOT checked is disconnecting the wiring harness to the injectors and cranking and watching to see if they leak under sustained fuel pressure. That's a test I'll do when I get a chance.

My fuel pressure is now as low as the stock FPR will go. That didn't really make a difference. I think the 11 lbs I reported was before I lowered the pressure, I haven't checked the pressure now but if the FPR worked at 11 lbs it seems unlikely it wouldn't work at a lower pressure.

I'll try the thing about opening the throttle all the way. Opening it partway definitely DOES help start.

The resistor seems like a possible way to bypass the problem but I would rather find exactly what the problem is and fix it if at all possible.

 

when my fuel pump was going out i was getting rich readings and it would stall after being started...if it was cold (wasnt real cold cause it was summer time) it would have more trouble starting

 

Have you checked for spark when the engine is cold?

I'm not saying that anything you've checked and replaced is wrong, but since you're getting fuel, and the car does start eventually, then you should check for spark.

My car did exactly what yours is doing, but on the other extreme of the weather scale. I would go to work, but if it was +90* day, I would be stranded at work for lunch. The damn car wouldn't start until I cranked it over 10 different times. Then it would run rich as hell for about 2 minutes after it finally started.

I would check for the fuel pump kicking on for start-up. Then checked the injectors after cranking (pooling up on the throttle plates). Those were fine. Then I pulled the #1 wire, layed it near an intake bolt, and got no spark.

I went through and checked every ignition source. The coil, pick-up coil, and then took the module to Autozone and it checked out fine. The next day it wouldn't start, so I had Autozone check the module again and it checked out fine. Layed it on the asphault in their parking lot for 10 min. to get it hot, and THEN it checked out as bad.

Replaced it and haven't had a problem since. Maybe I just got lucky. Well I wouldn't call spending 10 hrs on July 4th trying to fix it luck though. That was all spent driving 20 miles to the nearest Autozone, then 20 min. back again about 5 times.

AJ

 

Well, once again, I think I might have solved the problem. Yesterday I was messing around and had completely forgot about the IAC, or whatever controls the Idle Air Mixture. Anyway, It was making a buzzing noise which sounded like it was stuck and trying to move, so I took it off and hosed it down with carb cleaner and automotive electronics cleaner. A lot of stuff came out of it that looked like the black residue left from old fuel. So, I cleaned that up a bunch and put it back in. It has started both at 50 and 30 degrees, so we'll see if that was the problem. The car idles down a little faster after startup as well. It was taking nearly 3-4 minutes to go from the 1500 RPM startup to the 500 at normal idle. Now I am guessing it to be 2-3. It seemed to drop off a little more rapidly, but it is probly my imagination. I also made the misteak of starting the car up withouth the IAC in the TB. the little pin that closes the air off actally shot out of the controller, and the car was idling at 3k RPMs it was a little high for me though. So, hopefully that solved it.