90 zr1 no start

[mfranklin162]

Have replaced ignition module under intake and had ecm re-built, car will run on carb cleaner, I have checked all fuse and ohmed injectors between fuse and ecm with all reading between 12 and 12.4 ohms. I have no idea what to check from this point? Also vehicle has no codes and data all appears to be correct??

[Kevin]

fuel
air
spark

which isn't the car getting? are the fuel pumps good?

[mfranklin162]

good fuel pressure on gauge, has spark or wouldnot run on cleaner.

[scottfab]

Somebody put something other than fuel in the tank? water?
Using the fuel rail (and being very careful) drain some out.

[XfireZ51]

good fuel pressure on gauge, has spark or wouldnot run on cleaner.

When you say it runs on carb cleaner, is it running or just trying to start?
I'm skeptical that it is actually idling. The ignition module provides the start up control until 400rpms and then the ECM takes over.
What is good fuel pressure? > 47psi?

[GOLDCYLON]

good fuel pressure on gauge, has spark or wouldnot run on cleaner.


How many pounds of fuel pressure are you seeing at the rail exactly ?

[QB93Z]

Was any maintenance or repairs done to the car since the last time it started properly?

Jim

[A26B]

Sounds like ECM is not getting signal from eith cam position sensor or crank position sensor. If no signal then no command to injectors for pulse.

[Schrade]

Welcome onto the boards there...

How LONG does it hold fuel pressure? Static pressure (and bleeddown time) is WAY more important than dynamic pressure...

[mfranklin162]

I have 47-48 psi that hold well, when innitially crankling I get 1 injector pulse and it may pulse once in a blue moon while cranking.

[scottfab]

I have 47-48 psi that hold well, when innitially crankling I get 1 injector pulse and it may pulse once in a blue moon while cranking.

Starting to sound more like the crank position sensor like Jerry said.
Consult the FSM for details.

[VetteVet]

No or intermittent crank position sensor signal = no or reduced ref pulses from ICM to ECM and tach. Easiest way to check is to see what your tach is doing while cranking. If tach is showing cranking RPM, then crank position sensor and ICM are doing their part to provide ref pulses to ECM which are used for injector triggering.

Jep

[XfireZ51]

Jep,

That's what I was thinking. The intermittent injector pulse is coming from the cam sensor indicating #1. But the injectors won't pulse unless the ECM is seeing
DRPs, No DRPs w/o crank sensor.

[Hib Halverson]

The same OP was on the CAC.

Since you've already replaced the ECM and the DIS module (very expensive so far, I'd think), your problem may lie in either the wiring and connections between the engine and the ECM, between the engine and the DIS module, with the injector wiring or with the fuel supply. system.

Also, in the rare case where the SIR's DERM is disconnected, the engine won't start. If you find it discon. Reconnect it and try starting.

First, stop trying to run the engine on carb cleaner. Spray carb cleaners are very low octane and may damage the engine.

Also, you said you have spark but didn't say how you tested for it. When you test spark, be careful how you do it. One wire at a time with all the other wires connected. If you do it other ways, you may damage the DIS module.

Next, you need the Factory Service Manual and you should start with Chart A3 "engine cranks but won't run" on page 6E3-A-21. If you don't have the FSM, you need to get one and '90 is the only year during the LT5's run where the book is two volumes. There is the big book then a "Section 8A Supplement" and you need both. CAC sponsor, Zip Products, usually has them in stock.

The "cranks but won't run" diagnostic is 4 pages and requires some time to do, but if you run that diagnostic you'll likely find the problem.

To run the cranks but won't run diagnostic, you need a scan tester, a 12v test light, a spark tester, an injector test light (or "noid light) and your fuel pressure gauge.

Run the first part on Chart A3 pg 1 and post the results.

[ghlkal]

OP, here's the first page in the FSM

If you don't have this, I can post the other pages - LMK

http://i517.photobucket.com/albums/u331/NaturalCowgirl/ZR-1/90ZFSM6E3-A-21_zpsb4ca1399.jpg

[Schrade]

The same OP was on the CAC.

Since you've already replaced the ECM and the DIS module (very expensive so far, I'd think), your problem may lie in either the wiring and connections between the engine and the ECM, between the engine and the DIS module, with the injector wiring or with the fuel supply. system.

Also, in the rare case where the SIR's DERM is disconnected, the engine won't start. If you find it discon. Reconnect it and try starting.

First, stop trying to run the engine on carb cleaner. Spray carb cleaners are very low octane and may damage the engine.

Also, you said you have spark but didn't say how you tested for it. When you test spark, be careful how you do it. One wire at a time with all the other wires connected. If you do it other ways, you may damage the DIS module.

Next, you need the Factory Service Manual and you should start with Chart A3 "engine cranks but won't run" on page 6E3-A-21. If you don't have the FSM, you need to get one and '90 is the only year during the LT5's run where the book is two volumes. There is the big book then a "Section 8A Supplement" and you need both. CAC sponsor, Zip Products, usually has them in stock.

The "cranks but won't run" diagnostic is 4 pages and requires some time to do, but if you run that diagnostic you'll likely find the problem.

To run the cranks but won't run diagnostic, you need a scan tester, a 12v test light, a spark tester, an injector test light (or "noid light) and your fuel pressure gauge.

Run the first part on Chart A3 pg 1 and post the results.

OP; did you replace these parts? Why? What test confirmed broken parts?

If you're replacing parts without testing, I have the solution, 100% guaranteed:

DTC 0001vette. Replace vette. Send me old 'vette' and a small check for disposal fee of good 'part' [vette], and I guarantee at least equal success (or better) with replacement part [car].

[mfranklin162]

Ran flow chart a-3 by the book!! That is why I replaced the module, all pins tested good end to end!! Also ran crank no start chart, it stated to replace ecm, I happen to be an ase certified gm technician, I do not hang parts!!!! I went with the test results from the manual!! Hears a good one for ya, let car sit all last week, pushed it back in shop battery was low from sittin in the cold, charged battery while I was doin other things. When I went to the car hit the key and started right up. :confused:

[Dynomite]

Hears a good one for ya, let car sit all last week, pushed it back in shop battery was low from sittin in the cold, charged battery while I was doin other things. When I went to the car hit the key and started right up. :confused:

I am thinking if you topped off the battery to start with ;)
Sounds to me like a tad more voltage solved the poor connection including a poor ground (wherever it was) issue :thumbsup:

[scottfab]

Realistically it sounds like an intermittent and likely to come back.
It's best that it does now so you can find it.
No one likes to break down unexpectedly.
Keeping good notes on what you've done in what order
could be very valuable later on.
You'll need a game plan if/when it comes back.

Intermittent problems are the worst.

[mfranklin162]

Well, it started and ran two times, no wont start again, have not had time to get back on it, been pretty busy! Will post what I find when I find it!!

[Schrade]

Pintles in the injectors get electronically lazy after 20 years. Maybe a spray pattern test in in order here?

And while cranking (low RPM's), perhaps in injector light 'in a blue moon' isn't TOO far fetched? Once every 720 degrees.........

[Hib Halverson]

Gotta be one of those pesky intermittents.

[MEANDMYZR1]

Everyone, I believe this stream is about my car, posted by a Chevrolet Dealer trying to fix it. If it's not, it sure sounds like my car. It was at the Dealership for 5 months and I picked it up today without them being able to repair it. In fact, it sounds worse now then it did when I dropped it off. I guess it shows Certified Chevrolet Service can't make my car start. After replacing a number of parts, they said they didn't know what wrong with it. I appreciate you guys trying to give advice to help. Thanks, now I'm hoping I can find someone to fix it.

[vilant]

Sorry to hear about that. What did they do, tow your car back to your house? It's a shame your not closer to the wizards in IL or MD. Hopefully someone can refer you to someone nearby. Or if you want to tackle it yourself plenty of fellas here will try and help, through the forum. GL:cheers:

[MEANDMYZR1]

I had to pay to have it towed back, full of grease all over the inside and a motor that acts like they hooked the plug wires up backwards, and of course, doesn't start. They had it apart numerous times, no way of knowing what they really did. You would think Chevrolet would care, but they walked away. I've had the car for 21 years, it's sad to see it like this.

[vilant]

I would try and contact someone higher up like corporate or maybe the BBB. Dealerships are franchises aren't they? If it was greasy inside, I would've taken pics of it right away, there's no excuse for that. They should at least pay for detailing and cleaning it up after charging you for a job they never completed (I assume they charged for labor and parts). Do you own a scanner to read if any codes are stored?

[Z51JEFF]

Hib,the 91 FSM I have also has a supplement.

[MEANDMYZR1]

Pictures wouldn't do any good. Showed the inside to the service manager and he just started acting like I had two heads. They didn't charge me, they new they missed figuring it out in the first place and told me months ago the work from free. But that doesn't help when 5 months later they send it back worse than it left. Not showing any codes. I've had a few people send me some private reply's to this and I think I have someone that really knows ZR1's to send it to. I'll let everyone know how that goes over the next weeks.

[Hog]

I'm surprised you didnt get a bill. Diagnostics, however unfruitful do cost money. Maybe at that point in time, you did have 2 heads to that service manager.

There are 2 sides to every coin.

Really sucks that they cant get your car running, though we are at 15 years since any GM tech would have done any 3/36,000 warranty on a 1995 LT5. Be wary of dealerships at this point.

peace
Hog

[vilant]

Guess it was a lose-lose situation then. Sucks for both sides. Hopefully you'll have it up running in the not too far future. Let us know how you make out.

[Racinfan83]

I'm new to these cars but have some mechanical knowledge. And I'm just gonna throw this out there - as I have had a couple vehicles in the past that had an intermittent no start problem - and the switch was bad. Anybody try changing out the actual ignition switch?

[Dynomite]

I'm new to these cars but have some mechanical knowledge. And I'm just gonna throw this out there - as I have had a couple vehicles in the past that had an intermittent no start problem - and the switch was bad. Anybody try changing out the actual ignition switch?

Tom refers to a wire in the Ignition Key Cylinder goes bad (http://www.zr1.net/forum/showthread.php?p=169350#post169350)

zr1don has replaced the Ignition Key Lock Cylinder in his 90 ZR1 (http://www.zr1.net/forum/showthread.php?p=112876#post112876)

[scottfab]

A few things come to mind before shot gunning components and systems. That you may get lucky with it but this can be very expensive a even more frustrating than what's happened up to now.

The key to me would seem to be in data collection. If you can't find what it IS then find out what it is NOT.

Start over. Assume almost nothing.
Since it has been reported that it "runs on carb cleaner" then fuel seems to be the issue.
(this should completely eliminate the ignition: key, ignition, clutch switch etc)
So now then, if there is adequate fuel pressure at the rail (>40psi) then one would think injectors are not getting told to open. One thing we can assume is that whatever the issue is in the electronics (that which speaks to the injectors) it's intermittent.

The enemy of intermittent issues is data collection.
So now then, here is where you (or whomever) has to toss the FSM troubleshooting tree and think outside the box. Data about the injector circuit has the be collected. This will mean instrumenting such that this data can be seen. The best place has to be right there on one of the injectors. An easy mistake to make would be to use a chassis ground instead of the wires right on the injector (any injector). Another mistake would be to use data collected from the ECM (via a datalogger) because even if the system is demanding fuel it does not mean the injectors are getting the word.
The best way I know of to get the data right at the injector is with an oscilloscope.

So there you have it. Put a scope on an injector when the "no-start" happens while cranking. Even if the thing starts while you have the injector on the scope this data can be useful. It will show what the drive electronics looks like when working. This then can be used to compare to what it looks like during a no-start.

If the signal goes away at the injector you're almost home.

Whoever gets the task at finding this issue has to be determined, focused and pertinacious. Like a dog with a bone one has to resolve to find the SOB.

After 40yrs of such kind of work in electronics and software I can tell you that not all faults can be effectively found following a "service manual". Sometimes critical thinking is required.
May the force be with you :-D

[MEANDMYZR1]

Hello everyone. I wanted to get back to this. It took a while to get my car up to Chicago where Marc Haibeck fixed it in one morning. Then, he had to fix the other stuff the dealership put back together wrong. If I ever have a problem again, I'm not going to waste my time with anything else, I'm just sending it directly to him. He was awesome to work with and now my car is better than it has been in ten years. For all the others that emailed me to send it to him, thank you.

[Dynomite]

Hello everyone. I wanted to get back to this. It took a while to get my car up to Chicago where Marc Haibeck fixed it in one morning. Then, he had to fix the other stuff the dealership put back together wrong. If I ever have a problem again, I'm not going to waste my time with anything else, I'm just sending it directly to him. He was awesome to work with and now my car is better than it has been in ten years. For all the others that emailed me to send it to him, thank you.

Soooooo.....what did Marc do?

Or.......:D

Marc.....what was wrong and how did you fix it? ;)
And......what stuff did the dealership put together wrong?

[Racinfan83]

No doubt! After following this thread since the beginning I would love to know what was wrong with it!
And I'm gonna take mine to Marc as soon as I get the dollars together...fo
shore :cheers:

[MEANDMYZR1]

I elected not to say what was wrong with it because in the end I didn't have to pay Marc that much to fix it. So, I thought I would just let people send him more cars, so he can make some money, and continues to help us all like that.

[Dynomite]

I elected not to say what was wrong with it because in the end I didn't have to pay Marc that much to fix it. So, I thought I would just let people send him more cars, so he can make some money, and continues to help us all like that.

Good answere ;)

I understand that but I will now keep guessing. I will not ask Marc about technical issues of others for exactly the reasons you describe.....but I thought it was worth a try just once :D

Marc is definitely a super help on ALL technical issues :thumbsup:
Haibeck Automotive Technology (http://www.zr1specialist.com/)

[scottfab]

I elected not to say what was wrong with it because in the end I didn't have to pay Marc that much to fix it. So, I thought I would just let people send him more cars, so he can make some money, and continues to help us all like that.

Interesting.

[WVZR-1]

I elected not to say what was wrong with it because in the end I didn't have to pay Marc that much to fix it. So, I thought I would just let people send him more cars, so he can make some money, and continues to help us all like that.

I can't say that I understand that approach - most aren't "in the neighborhood" and some aren't even in the country! Quite a "contribution" you've made to the "hobby"!!

[Z51JEFF]

I elected not to say what was wrong with it because in the end I didn't have to pay Marc that much to fix it. So, I thought I would just let people send him more cars, so he can make some money, and continues to help us all like that.

Thats pretty good,you come over here racking everybodys brain,find the problem then keep it so yourself?Next time you have a problem just how many people do you think will be forthcoming to help you out and you will a problem with something.Good luck with that one Newbe.As far as Marc H goes all anybody has to do I give him call,hes more than willing to help an owner out.

[Racinfan83]

Yeah I have to say that I personally think this is a load of ####. He doesn't have to post how much he paid or anything else. And one way or the other - I am still planning on taking my car to Marc - so I don't care. But the whole idea of a forum is to HELP EACH OTHER OUT - and after we all did research and racked our brains thinking of solutions to help the guy (and the tech) fix the issue - the LEAST he could do is tell us WHAT WAS WRONG WITH IT!!!! :mad:

[Marc Haibeck]

Hi All,

Here’s a summary of how we fixed Pat’s engine.

The ECM was dead. It would not even pass the power-up self-test. In this state it can’t send fuel injector pulses. We installed a good ECM and the engine started.

There was a misfire and a thick stream of white smoke in the exhaust. We found that the switched wire for the number one primary fuel injector was pinched under the plenum. This causes the injector to run wide open whenever the ignition switch is on. The wire was freed and repaired. At this point the engine ran smoothly.

There was little activity from the left oxygen sensor. The stream of liquid fuel probably damaged it. The sensor was replaced and operation of the engine seemed normal.

Finally, we removed the plenum to repair three vacuum lines that were in poor physical condition. We normally test the operation of the secondary port throttles when the plenum is off. The ignition is turned on and then ECM pin C17 is grounded. The left bank port throttles would open only about 20%. Somewhere in the distant past, years ago, someone had removed the cylinder heads. They did not fully tighten the secondary throttle shaft nuts. All four of them were loose. This causes the throttle plates to slip when the actuator arm is moved. We correctly tightened the throttle shaft nuts. I noticed that the engine has about 40 additional hp now that the all of the secondary port throttles open fully.

[Blue Flame Restorations]

Thanks for the explanation of events, Marc. Always nice to hear you walk through things.

Brett!

[Dynomite]

Thanks Marc.....WOW....who would have guessed ;)

Cliff

[Racinfan83]

Thanks Marc! It's always good to know what to look for...

And I am looking forward to bringing mine up there when I get the funds! :cheers:

[scottfab]

Hi All,

Here’s a summary of how we fixed Pat’s engine.

The ECM was dead. It would not even pass the power-up self-test. In this state it can’t send fuel injector pulses. We installed a good ECM and the engine started.

There was a misfire and a thick stream of white smoke in the exhaust. We found that the switched wire for the number one primary fuel injector was pinched under the plenum. This causes the injector to run wide open whenever the ignition switch is on. The wire was freed and repaired. At this point the engine ran smoothly.

There was little activity from the left oxygen sensor. The stream of liquid fuel probably damaged it. The sensor was replaced and operation of the engine seemed normal.

Finally, we removed the plenum to repair three vacuum lines that were in poor physical condition. We normally test the operation of the secondary port throttles when the plenum is off. The ignition is turned on and then ECM pin C17 is grounded. The left bank port throttles would open only about 20%. Somewhere in the distant past, years ago, someone had removed the cylinder heads. They did not fully tighten the secondary throttle shaft nuts. All four of them were loose. This causes the throttle plates to slip when the actuator arm is moved. We correctly tightened the throttle shaft nuts. I noticed that the engine has about 40 additional hp now that the all of the secondary port throttles open fully.

See it's stuff like this that builds trust and confidence such that why would you take your car to anyone else when the time comes?