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'94 Camaro 3.4L Cranks but No Start

44912 Views 45 Replies 7 Participants Last post by  Spoonyg
Hello, I bought my Camaro new in 1994 and have had very good luck with it until this past Sunday. My son backed it out of the driveway and when he put it in drive, it quit running and I haven't been able to start it since. The first thing I did was to check the oil and it smelled strongly of gasoline. The engine turns over, and sounds like it wants to start but won't.

I have replaced the following items with new parts: Spark plugs, SP cables, Ign. coils (all 3), O2 sensors (the 2 on the exh. manifolds), air filter, fuel filter, and fuel pump. I have also changed the oil and the oil filter.

I'm kind of stuck now on how to proceed, (my limited imagination is at an end at the moment) whats the next step, shy of towing it to a real mechanic. Any and all suggestions will be greatly appreciated.

Thanks Brad
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before replacing the motor(just kidding) do some diagnostics...pull a plug wire...put an old plug in it, rest it on the intake or other metal surface, and have someone crank the motor...see if there is spark or back, and we can go from there...

I tried one plug and it sparked. However, my battery has decided that it is getting old and tired of trying to start the engine. I've got it hooked up to a charger now and will try the rest of the plugs later this afternoon. I think this battery is about 4 years old so I'll probably put a new one in this afternoon also, depending upon how well it holds a charge.

Thank you
Ok, back to it. The spark plugs have spark. My battery seems to be holding its charge for the time being. When the engine is turning over, it sounds and smells like its flooded. Could this be caused by the fuel pressure regulator malfunctioning? Delivering to much fuel to the injectors.

If it smells like raw gas while cranking, then hold the throttle to the floor while cranking. The engine is being flooded. You may have to remove the spark plugs and either dry them out with a shot of compressed air, or replace them with new plugs.

Too much fuel could be pressure regulator being broken, but unlikely because there is no vacuum created, engine has not started, to start the regulation cycle. It needs vacuum to regulate, no vacuum means regulator is supplying full fuel pressure, as shown by wet (?) spark plugs.

The engine may be overfueling due to a defective ECM coolant temp sensor. This sensor tells the ECM how cold the engine is and the ECM looks up in a table, along with other sensor inputs, and determines how much fuel for injectors to inject. This function is like the choke system of a carburetor, low air flow (closed choke plate) with X-amount of fuel = rich fuel mixture. ECM cold start sytem works in the opposite way, same amount of air flow with X+Y amount of fuel = rich fuel mixture.

When you were checking for spark at the plug, you should hold just the wire with a screwdriver inserted into the boot and hold the screwdriver a 1/4 inch away from ground and look for the color of the spark. Blue is best. If orange in color, not enough voltage to ignition to create a blue spark or a poor ground at the DIS coilpak(s). Maybe others here can come up with a better spark troubleshooting technique as this suggestion may damage the coil, as the older ignition systems, one could check this way.

Once you do get the engine running and for some time, you may want to change the oil again to remove the fuel if the smell curls your nose hair. I'm sure you are reading your newly purchased Haynes manual and reading up for other suggestions.
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Thank you Everett,

The spark plugs were wet.

I'll switch out the temp sensor this afternoon.

I also ordered a FPR diaphragm kit that should be in this afternoon.

I'm heading out now to pull all the plugs and let cylinders and plugs dry out for a couple hours. I'll change the oil & filter again right after it fires up and runs for a few seconds (or minutes).

I bought the Haynes manual back in '95-'96 when I first saw it at AutoZone it's been a real life saver. I think I've read it from cover to cover about 3 times. And now a fourth time during this problem. Unluckily it only devotes about 1 paragraph to the FPR for a 3.4L.

edit: I read on this forum somewhere about the same problems and it turned out to be the FPR was the culprit.

Thanks for your input, it is really appreciated.
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Just an update. still not starting.

Checked the temp. sensor and it came close to the resistance that Haynes noted so I didn't replace it (Can't check it with a hot engine though).

I tried checking for trouble codes using the jumper method on the ALDL between the Diagnostic TEST terminal and ground. The SES light lite-up but never flashed.

Question 1: Does this have to do with disconnecting the neg. battery terminal and erasing the ECM memory or is it a sign of a defective ECM?

The FPR diaphram kit install went smoothly however no different results.

With the cash I've thrown at this car so far this week it should be running better than it has in years.

Question 2: The spark appeared to be orange/yellow not blue. I bought AC Delco spark plugs and they are gapped at the recommended 0.045". Since I'm probably gonna have to remove the plugs this evening again and let the cylinders dry out would it be a good idea to replace these plugs and with what kind due you folks recommend.

edit: Question 3: Forgot this one, would a clogged Catalytic Converter or the timing chain be a culprit to not starting. (Car has 145k miles.)
Thanks Again
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I tried checking for trouble codes using the jumper method on the ALDL between the Diagnostic TEST terminal and ground. The SES light lite-up but never flashed.
SES light should at least flashed a code 12, regardless of codes its holding or not.

Question 1: Does this have to do with disconnecting the neg. battery terminal and erasing the ECM memory or is it a sign of a defective ECM?
Disconnecting battery cable erases fault code memory, and whatever the ECM has learned from past history to make the engine run smoothly, as in old age, and reset itself to manufacturer's program. Kind of like defragging the disc or CD.

Question 2: The spark appeared to be orange/yellow not blue. I bought AC Delco spark plugs and they are gapped at the recommended 0.045". Since I'm probably gonna have to remove the plugs this evening again and let the cylinders dry out would it be a good idea to replace these plugs and with what kind due you folks recommend.
Good idea to let everything dry out and try again. You've replaced the plugs already, no reason to replace again. Haynes should give the best spark plug number for the engine. Depending upon oil consumption after driving for some time, I'd probably go with the next hotter heat range to help keep the electrodes clean. Looking at the OE plugs and seeing a nice tan electrodes would indicate the proper heat range.

edit: Question 3: Forgot this one, would a clogged Catalytic Converter or the timing chain be a culprit to not starting. (Car has 145k miles.)
Thanks Again, Brad
A jumped timing chain will prevent starting. Compression gauge might read 100 PSIG if chain has jumped.
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Thanks again Everett,

I thought the SES light should have flashed.

I talked to a friend earlier this evening and his first thought was the timing chain. So, tomorrow morning he's heading over and we're gonna pull the front of the engine off and replace it, I've been dreading this, and have refused to talk about it. I watched my dad replace timing chains a few times but have never attempted it myself. SWMBO reminded me at dinner that we used to own a Ford Escort that threw timing belts every 50k miles and had the same symptoms as the Camaro does now (must be that "old age" thing, I just can't remember).

So anyways that is the next step (I think).

I can't wait to get my Camaro out of the garage so I can get back to my favorite hobby, brewing beer. My kegerator is starting to run a little low.

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Keep us informed of the outcome.
hey everett, is this a mass air or speed density... bad maf or map can cause a rich condition...wet pluge arent usually due to a timing chain, but possible...when a chain jumps, the car will usually turn over faster than normal, due to loss of compression...i`ve also seen cars that wont run after they`ve been jumpstarted, because the voltage spike changes values in the computer learn area of the prom...disconnect the batt for 1 minute to reset values to predetermined table...a plugged cat would have to be plugged pretty solid to make the car not run, but would make the plugs wet, because exhaust gasses wont get out of the can drop the y pipe to see if the cat is the culprit, but dont run too long if it could bend valves from running just at manifolds...
I believe it to be a speed density system, but either set-up, MAF & MAP are not in the start function, there is no vacuum created for either to work to start reporting any values.

A manual check of at least one cylinder compression will show the condition of timing chain if it has jumped, low compression, no vacuum.

Or so I think.
i`d like to hear what it turns out top be, as these problems help techs diagnose difficult problems in the future...i only mentioned the map/maf because i had a caravan once that would run for one hour straight, and then just wouldnt start back up until it cooled for 20 minutes...there was a bad wire in the map harness...when the engine bay temp rose, resistance in the sensor wire went up, changing the map value, and leaning the car wouldnt start affter that, until wire resistance came back down, and the comp got a good reading...i unplugged the map, and the car started right up with a mil light on to tell me that i forgot to plug the sensor back in...(i found the problem purely by chance!!!)i didnt know if the comp in the camaro would do the same thing...and everett is right...check compression before ripping into the`ll cost more time, but alot less money usually...
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Hi Guys (kustomwerker & Everett),

Just to let you know that I haven't given up. I've got the front of the engine off and the T-chain exposed (new chain & sprockets due tomorrow, Monday, at 12:30 pm) my arms were really tired last night, I could only lift a few pints. My initial thoughts are: the timing chain has a lot of slack in it, however, it hasn't, visually, skipped any teeth. However, both sprockets look worn. I'll know how loose it was when I put the new chain and sprockets on tomorrow afternoon.

One thought, on the side, I didn't have to remove the water pump from the timing chain cover to remove the timing chain cover. This is going to be another gasket that I have to replace. Haynes steered me a little off. Also, they (Haynes) recommened that I remove the oil pan ( I didn't).

I didn't change out the MAP sensor because it is vacuum supported and Everett is right. No vacuum until the engine is running so... I'll find out tomorrow evening if this works.

BTW, I do get exhaust fumes out of the tail pipe (strongly). So I have to assume that my CAT is not clogged to the point of not starting.

Thanks again guys your thoughts and comments are greatly appreciated and have kept me motivated to keep going.

(edit: I talked with my neighbor today and he has a cylinder compression gauge. If it doesn't start Monday evening I'll let you know what the compression psi is with this no start.)

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You said that the oil smelled of fuel. You need to install a fuel pressure gauge and check to see if the fuel system holds pressure. you could have one or more injectors leaking fuel and flooding the engine.
There could be a possibility of the MAP sensor being bad. An ohmmeter between one outsuide terminal and the center terminal and a hand vacuum pump on the nipple and slowly apply vacuum to show on the ohmmeter a smooth reading from one end of the scale to the other. Should be no 'holes'.

When taking a compression check, unplug INJector fuse(s) and hold the throttle at WOT (wide open throttle).

The new chain should give 1/4 inch of slack with the other side of the chain tight.
Hi Guys,

Thanks for the replies.

I just got the old gasket mat'l removed from the covers and engine block. I will probably be putting the T-chain back on tomorrow. The old chain had about 1/2" of slack with the other side tight. The water pump gasket came in the gasket kit, yeah, something went my way. Removing the water pump was not a big problem really, so I'm glad I followed the Haynes advise. They didn't steer me wrong.

I'll check out the MAP sensor next, one way or the other, this car will run again. I'll also check out the fuel line pressure and make sure it is not loosing pressure.

I'll check back in when I get everything re-assembled.

Thanks again,
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if its a leaky inj, or fpr, the fuel pressure guage will peak when you turn on the key, and then drop...if everything`s good, it should hold pressure at the rail indefinately...i had a bad fpr diaphram on a 351w ford that pushed fuel up the vacuum supply line into the intake plenum, and choked the car right out...if you pull the line off the fpr and turn on the key, you`ll see immediately if thats the prob..t-chain play would have to be a lot more than half inch to jump time, although tis not a bad idea to change at your mileage...i`d hate to say ecm, but you`re running out of things to check,change...if you could get ahold of a scanner, you could get a data stream from the computer if its good...(you did check all the ecm fuses right???)if the fuses for the ecm are bad, you wont run...if the ses light didnt flash when you jumped out the aldl, that would have me puzzled...did you disconnect the batt to clear the comp???just checking...also try unplugging the cam sensor...sometimes a sensor can go bad, and the car wont go into limp mode because the comp cant tell that the sensor is bad...if you unplug the sensor, the computer will see that, and revert to a baseline that it knows will work even if not optimally...reguardless, there is too much fuel getting into the car, and there is only so many things that can make that happen...if i was there to test things, i`m positive i could make it run through diagnostics, but without being there, its sometimes really difficult and frustrating...i hope you get it soon...maybe everett has some more input...thats a smart guy...
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Brad.I read your posts.Sounds like you are rich as heck.Either to much fuel or not enough air.Did you check for a K-mart bag sucked up into the air filter?Sounds simple...but happens quite frequently.I once had a rodent fill an airbox with dog food from the garage and resulting in a no start.FWIW,I just replaced a skipped timing chain for a no start.What tipped me off was the cylinder pressure was 40 psi above normal.Not all chain fails cause retard..they can and will advance the cam timing..grabbing more cyl pressure,but throwing off spark and injector timing.
Stop it ........ You're making me blush. I'm waiting for him to get it back together and go from there.

One thing you can do Brad, is to make sure all the ECM grounds are attached at multiple places and ensure they are making good contact to the block. You can make an ohm check from the terminal crimp to the block and ohmic value should be less than 1.0 ohm.

If and when you do get ready to start, check TPS voltage for its correct setting, approx 0.4-0.5 volts, closer to 0.5, check base timing with the dist in bypass, and base rpm with IAC unplugged and seated. The Haynes manual will guide you through it. And obviously look at the injectors to make sure they are not leaking.
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