Something stupid??? I HOPE!!!
 

Hey guys. I am a new Z owner, 3 Corvette but first ZR1. Ok, history first. Picked up the car from a buddy of my brothers, he said it wouldn't start...cranks but won't start. This guy was in some financial trouble and picked it up for...wait for it....3,000.00!! The car could use a good buffing, but immaculate interior and only 41,000 on the clock!!! So it was definitely a worthwhile investment for me! So...the story goes this kid was given the car from his father, 2 1/2 years ago, he was driving it to the gas station and it just died. He brought it home and didn't have the money to get it checked so it just sat for the last 2 1/2 years. So...of course I changed the battery and dove in to try to bring her back to life. Like he stated, cranks over but doesn't start. It sometimes seemed like it wanted to start, but then just drone down to cranking over and over. I checked the pressure at the rail and holy crap!!! The fuel was like oil and stunk like a 5 gallon jug of 2 stoke gas that sat in the sun for years! I changed the plugs and dumped a little gas down each cylinder to see what she would do. It fired right up and then promptly died and just cranked. So I turned to Jerry for new plenum gaskets, fuel rail seals and wires. I also ordered new coils, and all injectors. While I waited for shipping, I accomplished the fun and exciting task of dropping the fuel tank. Cleaned it out and blew out all the fuel lines as well as installed a new filter. Last night I replaced all the parts I received and was excited to see what would happened. Fuel pressure was great...turned the key...no dice! Same thing, just cranked over. After some research I found that some guys had issues with the ECM as it controlled the injectors. I pulled a plug after trying to start, and it sure looked dry! No fuel on it. So today I picked up a reman ECM, switched the PROM and figured I would be cruising right now! NADA!! Same thing!!! So now my hair is white and at kinda of a loss on what to look for or where?? ANy advice guys? Maybe a good direction of where to look or what to test? I really don't want to have to take it to the shop!! Oh BTW...before swapping the ECM, when I would turn on the key you would hear the norm...fuel pump charging, and some noise under the hood for a few seconds. When I put in the new ECM and turned the key...the cooling fan comes on and there is a valve on the inside of the front drivers side fender that is blowing air out. Both of these key running as long as the key is turned on. Any help would be greatly appreciated! I love this car, and just can't wait to take it for a drive!!!! I am a active duty Marine and there is a combination of pride in not wanting to go to the shop, as well as the fact that as you all know..we enlisted servicemen are not exactly rich!!!:-D Thanks again guys!
Erik
Erik

Re: Something stupid??? I HOPE!!!
 

Needed to add- the car is a 1991! Can't believe I forgot that!

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Hello YZPilot, welcome to the forum. Reading your post tells me that the car will run if fuel gets to the cylinders as per your test. That also tells me possibly your injectors are not pulsing. Did you check the injector 1 fuse? That drives the primary injectors to ground in the ecm. Do you have any codes stored?

Re: Something stupid??? I HOPE!!!
 

Hmmmmm

Have you checked the fuel pumps?

Sounds like no fuel.

:cheers:

David

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ZZZZZR1 that is a good question too. YZ, you checked the fuel rail but did you pressure test it? Should be between 48 and 55 psi.

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@Franke...I did check the fuses...all good. You know how it goes when your in that worried parent mode! In fact I checked every fuse on the car. Everything looks good. I put a OBD I computer on it but I just keep getting a "cannot negotiate with the car" message! UGH!!! Not sure if you can get these to flash codes on the info panel or not? Guess I should check that. The lack of pulsing is the conclusion I have come to...so now it's just a matter of finding out what is not sending the command to pulse.
@ZZZZZR1...I checked both pumps, working great...I have good pressure at the rail and it holds steady. The fuel is getting to one side of the injectors...it's just not coming out the other side! Lol!
Thanks for the responses guys! It's good to be a member...and owner!!! Even if it doesn't run yet! ;-)

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I'll give ya $3500 for it, LOL just kidding:)

Like David just suggested did you actually check the fuel pressure with a gauge? the pressure has to be within specs. Get a factory service manual it will help greatly. These manuals have good trouble shooting sections...jimmy

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He did mention the fuel pressure was great,so it's not that.
I'm thinking anti-theft system.

Al.

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YZ, you can enter diagnostic mode by a jumper from pins A to B of the ALDL conn. A is the first terminal from the right of the ALDL connectors top row and is Ground. B is the second terminal from the right of the ALDL connectors top row and is the ECM diagnostic term. it will flash the SES light code 12 three times and then give any stored codes 3 times as well. Turn the igniton to on after grounding the "B" term. Do not start the engine.

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been a long day...fuel filter? I doubt injectors are the cause of it not running even with a few dead injectors it'll still run, though they need to be changed i'm betting

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Ok..you guys...I just made a big liar out of myself! You guys got me wondering, so I just went out to the garage to check the fuel pressure. Keep in mind I checked the pressure yesterday with the old ECM. So...I just checked...and 0!! I have nothing! The pumps aren't even kicking on! WTF!!! I put power leads to the harness by the fill cap and both pumps are working great! Pressure was right at 53. But hook the harness back up...turn the key and nothing! Just that damn cooling fan and air pump! I am really getting frustrated! And thanks Franke...gonna go see if I can pull some codes now.

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@ Kevin..brand new injectors, new filter, new plugs, wires, coils! Sure thought that would have solved the problem!

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YZ, also thinking out loud, did you repeat your gas in the cylinders test after you replaced all those parts? Does it start and run then quit? You replaced quite a few things in hopes of a cure but may be in a different area of trouble shooting now.
ALZR1 if the vats system was the problem I don't think the car would crank as the starter enable relay would not operate. Correct?

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"Franke...gonna go see if I can pull some codes now. "

YZ I am assuming you do have a SES light when the key is turned on. Correct? If you don't then you are missing 12 volts to the ECM and 12 volt supply.

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Franke, I am seeing 2 lights. One in the LCD display where the fuel guage is, but it says SYS. It is continually flashing 12. And on the info display I am getting a "service LTPWS" that also flashes 12 over and over. And as for your question...I have not tried the gas in the cylinders again since I replaced everything.

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I wouldn't worry too much about the LTPWS as that is the low tire pressure warning system and won't affect the engine start. Sometimes the LTPWS goes on occasionally then off. There are some threads about that system on the forum. I think you should have a ses light but not 100% sure. Do you have an after market radio?

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Brain storming that is correct.was looking as possibilities



AL.

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YZ correction to previous post. Could be a sys light as you mentioned. Another post from another source...

"Any time a sensor's output exceeds a Hi/Lo reference parameter stored in a Programmable Read Only Memory (PROM) array in the ECM/PCM module, an error code is set and retained in the ECM/PCM memory.

This event causes the lighting of the Malfunction Indicator Lamp (MIL) on the "tell tale" panel (more commonly known as the "Check Engine" light) or the SYS (System) lamp located on the instrument panel above the speedometer on later C4 automobiles .

If the problem clears and remains cleared for 10 seconds, the light will extinguish however, the error code is still stored in the ECM/PCM memory.

Regardless of whether the problem is constant or intermittent, the error code can be recovered through a user friendly system involving the MIL (Check Engine) or SYS lamp.

To the immediate right of the steering column under the dash, you will find a multiple pin electrical connector. This connector is called the Assembly Line Data Link (ALDL).

From 1984 until the end of the 1993 model year a 12 pin ALDL was used. After that, a 16 pin ALDL connector was used. The 1994 and 1995 model year still used the OBD-I system even though they have 16 pin connectors. The 16 pin connector in the 1996 C4 is used for the much more complex OBD-II system and a scan tool is required to discover the OBD-II system's secrets.

The early ALDL connector has room for 12 pins however only 7 are populated and of those we are only interested in Pin "A" and "B" for this procedure."
Code 12 is the correct code.

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Should the ses light be on the info center? If so, I'm not seeing it. The radio is stock. That's why I love this car, everything is stock except for what I replaced the last few days! Even still had the lt-5 spark plug wires on it...in great condition except one!

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Thanks Franke. So, my sys light is just flashing the all clear code! :-( But then again, I just changed the ECM, so that's probably why it has no codes stored. They took the old ecm as core!

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Before you go changing fuel pumps change out to the old ECM.

You mention that with the new ECM when you turn key on the fans go on
tell me ECM is bad or something wrong with the chip.

Pete

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Hey Pete, unfortunately they took the old ecm as a core! Is there anyway to check if a ecm is good or bad?

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If you can recover your old ECM get it - regardless of your situation get the ECM core - pay the core value and hold it until the car runs. You shouldn't part with a core until you know you've received a "functional" good part.

I'd like to think it's not to late!

Post the part number from your invoice for the ECM that you purchased!!

Re: Something stupid??? I HOPE!!!
 

Al,

Would he be able to even crank the motor if it was the VATS?

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The "fuel enable" aspect of VATS will allow "crank no start"!

I would seriously consider checking the CCM for faults. Either from a scan tool or just from the DIC module using this tool:

http://tech.corvettecentral.com/2011...trouble-codes/

Re: Something stupid??? I HOPE!!!
 

Referring to page 9D-2
there is no such mode as "crank no start".
Both fuel AND cranking are disabled together.
The CCM sees to it.

I submit, the problem at hand is not VATs related.

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OK, marine lets nail this...........
Not sure where you're at with this but having another Z nearby that could come assist (parts swap) would be a GREAT advantage.
Anyone reading this from the Pacific Region that can chime in?

Short of that and after reading ALL of what you've written in the OP and all comments made up to now here is how I would proceed.
Forget INFL RST light. Forget Theft Deterrent issues.

1. If you can't get the original ECM back at least recheck all the connecters going into the ECM. Remove each and inspect for bent pins.
Also open the little cover on the ECM where the chip is installed. Check for pins not properly installed. Given no apparent issue you're going to have to proceed and assume the ECM is ok for now.

2. It would seem you have no fuel pressure at the rail but when you first flick the key on does it come up to about 50psi for a short time?

Staying with fuel for now can you connect a the pressure assembly and bleed off fuel repeatedly when you cycle the key on/off every 60 seconds?

Now, if you get an initial surge of fuel then nothing you could be looking at a failure in the primary pump but the secondary pump is fine.
At start both are on for 2 secs then only the primary is left to give fuel.

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Fuel enable can be turned on or off in the PROM and is controlled by the signal from the CCM I believe. I won't debate the issue but yes there's a "fuel enable" and I believe the correct CCM code for it's failure might be 54. That's the primary reason I suggested going to the CCM to check for errors.

Adding to your items to check is maybe first of making sure the PROM is correctly seated in the ECM. That I might think of the most important starting point given all of the previous information. It might be wise maybe to post the information from the PROM - maybe it has someone's "autograph" on it. Maybe! Is it important? Likely not but it would be wise to note it.

Cranks but won't run is covered in 6E I believe and has it's own chart. I don't have a correct FSM but I'd guess maybe it would be A-3

OP - the code if it's an OE would be seen in one of the "windows" in the blue PROM cover on a silver label. Just note that information, it could become valuable later to you. Not for this issue maybe, but it will be of value I'd think.

You check first the things that you've done your self. The first thing you did when you replaced the ECM should have been to install the PROM - I'd start there. Just makes good sense!

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Thanks so much for all the input guys! Unfortunately, as I am moving into my new base housing this week, I am going to have to wait until the weekend to continue on. The car is at my parents place in vegas, and I'm getting ready to head back to Cali shortly. So hopefully this thread won't die, because I really value all the input from you all! And Pete, I almost stood at parade rest when I read your post! Lol. But yes...ready and willing to nail this!! I would love to my wife to the Marine Ball this year in a ZR1 chariot!! So here's is the newest update for today. On the line of WZR1's thought train, I spent half the night doing research on the ecm I got yesterday, and low and behold I do believe the ecm they have listed as for the Z, is actually for a LT1! Last 4 of the part number is 7727. As far as I can see the pn for my car should be 16163993. This probably explains why with the new one, all of sudden my fuel pumps no longer engage, but my cooling fan sure as hell does! Thats what I get for making the rookie mistake of buying a ecm through autozone!! I really should have known better!! But the good news is, they still have my core, and I will pick it up on the way home today! Hopefully this other unit didn't fry my prom! Pete, since I will have the ecm and prom for a week, and no car...I will give the ecm and prom a good thourough examination. And I guess we can proceed from there! Do you think I should go ahead and order the correct ecm...or do you think there is a chance this could a non ecm related issue? Either way, this is going to be a long week waiting to get under the hood! At least she will be on a trailer coming back with me next week! This week is sofas and furniture!!! UGH!!! Thanks again guys!!!

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As far as I know ECMs for the LT5 are NLA, so I doubt you could get one from autozone or any other car parts store.

Not unusual to get L98 or LT1 parts when you go to these places.

Lots of symptoms point towards the ECM, but as I was told, the ECM rarely fails.

You did mention SYS flashing, this is generally a weak battery. The ZR-1 is very sensitive to a good battery. My car was having strange issues that pointed to the ECM, but a new battery and all was good.

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It's good to see that you were able to recover the ECM - now just start over with the correct ECM/PROM combination and let's see if "life can get good"!!!

You've accomplished a good bit with just the "recovery" - more than you can likely imagine!

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Bingo,make sure the ECM and prom are seated right.

If you have fuel (45-50 psi) check fuses then check for spark.

Also you might wanna check crank sensor (under car right side of motor next to the dipstick.


Pete

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Agree...
I am receiving orders for the CPS (crank position sensor) more frequently. Owners are finding small cracks in the sensor and intermittent "opens" (no resistance when checking ohms) CPS electrical connector should be cleaned & made sure it's tight.

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I'm 15 miles down the road. I have a tech1 scanner and a spare known good ecm and prom for a '91. PM me when you get in town.

Mike

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Ok guys...I have to say, the best thing I have done since I bought this car is to join this forum!! Really, thanks for everyone's help and input. With that said...Mike, you probably just became my best friend! PM is going out now!

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Jerry, I'll be sure to check that cps as well...also, thanks for the quick and great service on all the other parts!!

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Somebody's car is running again (on the loaner ecm)...:cheers:

It complained and clattered for a few minutes and was only running on 7 cylinders, but the valvetrain pumped itself back up after the oil got hot. I guess it had sat for 3 years+

Needs a 91 ECM. Full comms with the tech1A, but my guess is the Injector Driver is stuffed- intermittent fueling, won't start easily/ at all. IGN present, tach signal present and displayed on scanner etc.

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Can't ever thank Mike enough!!!! SO to my relief, as Mike mentioned, she is alive! Felt so good to take it for a drive! So as Mike mentioned, the ECM was definitely the problem. Soooooo....anyone out there have a ECM for a 91 laying around they want to unload? Or anybody have recommendations as to the best person to send this off to for a rebuild?? Thanks for all the help guys! And again, Mike, can't thank you enough! Sleep will be good tonight! And good call on the beer! Might have found my new favorite brand! Lol!

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Correct me if this is false, but I believe I read that the later years cars' ECM's can be used in the earlier cars but not vice-versa.

So you should be able to use an ECM from a 91-95 car, right?

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I have heard that is true, but never personally tried it.