General Maintenance & Repairs - Desperate for help (any advice would go a long way)

I posted in the Western Forums but there wasn't too much response, and I'm praying someone in here will maybe know the problem.

My car is an '02 Z28 with 72 thousand miles. Normally, the car drives and starts absolutely fine, something like...49/50 times. But on that 50th time, it just won't start. IT'll try to turn over and turn over, and nothing will happen. If I try and start it a good 10 or 11 times, it sometimes will turn over miraculously.

I've taken the car to 6 shops now. I was originally advised it was VATS, so I had JBA disable it and followed up with CMS, who said it had been properly done. I've had the fuel filter replaced at a different shop, and then took it to another shop just the other day because the car died on me while I was driving. I was cruising at 55 mph, and all of a sudden, the engine just seemed to lose power and died.

When I got the car towed over to the shop, it started just fine, and drove fine. I was so pissed, but I left the car at the shop, hoping they'd replicate the problem. They did. They said the fuel pump was fine, and it was probably the crankshaft position sensor. Had that replaced, and then they calleed and said the car had done the same thing. They then said it HAD to be the ignition security system, and I should take it to the dealer. I told them I had it tuned out, they said it probably wasn't done right.

I've already spent so much money just trying to figure out what the problem is, and I'm honestly worried to drive on the highway. It's my daily driver and I love the car to death but I'm worrieda bout it just dying one day on the highway.

If anyone has any ideas, please feel free to post them, as nobody can figure this out and it's just gotten depressing at this point.

Thanks in advance.

Does the engine turn over but not start? OR does it do nothing?

Turns over but doens't start. I've been doing some reading and a lot of people have said they've had similar problems with the fuel pump relay...

do you hear the fuel pump kick on when u turn the key and it doesnt start?

Try changing your ignition relay. You can just swap it out with a fan relay. Just make sure that you put it back in like you took it out.

At this point it could be anything considering the age of the car and parts. However, I'd recommend taking it to a dealership because it seems like these other shops are just throwing on parts. I get a lot of these situations where the customer has been to several other shops who can't fix the problem. In the end it's usually something simple that was overlooked or the shop didn't take time to duplicate the problem. If you want to fix the car yourself I'd start with running a pressure gauge off of the rail so you can see if it doesn't have fuel pressure when the problem occurs. Also, I'd keep a spark tester handy and as soon as the car dies pull an easy wire off and check for spark. Furthermore, I'd keep an injector node tester handy and also pop and injector plug off to check for injector pulse. Depending on what the outcome is it should get you headed in the right direction. Good luck!

i would suggest a trip to the dealer instead of throwing parts at it

I went to Autozone, replaced (both?) fuel pump relays and so far, after about ten starts, no problems so far...

If it ends up being the relays and all those shops couldn't figure out what it is, I'll of course be stoked but god damn...

I went to Autozone, replaced (both?) fuel pump relays and so far, after about ten starts, no problems so far...

If it ends up being the relays and all those shops couldn't figure out what it is, I'll of course be stoked but god damn...

Yeah, it's about the age for relays to start acting up. I hope it works out for you and it doesn't surprise me that a shop couldn't figure it out. In all honesty they probably didn't get the car to act up and just started piling parts on.

had a similar problem with my 02. hope it was just the relays. replace them all of the time at work. good luck....

Man, I've had this issue for MONTHS now, and have spent a decent amount of money between diagnostics, having the VATS removed, fuel filter replaced, countless tows...I'm really hoping this is it.

Man, I've had this issue for MONTHS now, and have spent a decent amount of money between diagnostics, having the VATS removed, fuel filter replaced, countless tows...I'm really hoping this is it.

Hopefully it was the relays. As a precautionary measure, maybe put a fuel pressure gauge and some starter fluid in the garage next to the car, and in the event that the problem emerges again, you can do some very simple troubleshooting.

1) Turn the ignition off and back on. Listen for the fuel pump. If it primes for two seconds, go onto step 2. If not, check the fuel pump relays (which you've already done at this point), in addition to the fuel pump fuse.

2) Turn the ignition on and test the fuel pressure at the rail. This will give you some detail on the problem, but will not pinpoint it exactly. It'll let you know if the fuel is getting from the pump, through the filter, and into the injectors. Regardless as to whether the pressure is adequate or inadequate, move to step 3.

3) Open your lid, and have a friend spray a small amount of starter fluid into the intake manifold as you are cranking the starter; if the engine starts up momentarily and then dies, you know your spark and compression are good - and that the fuel is the culprit. If not, you're in the spark and compression realm - narrow down the problem from there.

The key is to wait patiently for the one time that it will turn over but not start, and pinpoint why it won't start. I can imagine the dealer's frustration when you bring a problem to him that happens "one out of fifty times."

Just my luck, car didn't start tonight after basketball. Back to the drawing board...anybody have any ideas?

It cranks and cranks and cranks, and when I let go it feels like the engine is shaking a bit, like there's no fuel (but that's just a guess.) I don't know if it was by chance, but I popped the hood and took out the smaller of the relays (20A), put it back in and the car started.

I knew the relays were too good to be true...

Hopefully it was the relays. As a precautionary measure, maybe put a fuel pressure gauge and some starter fluid in the garage next to the car, and in the event that the problem emerges again, you can do some very simple troubleshooting.

1) Turn the ignition off and back on. Listen for the fuel pump. If it primes for two seconds, go onto step 2. If not, check the fuel pump relays (which you've already done at this point), in addition to the fuel pump fuse.

2) Turn the ignition on and test the fuel pressure at the rail. This will give you some detail on the problem, but will not pinpoint it exactly. It'll let you know if the fuel is getting from the pump, through the filter, and into the injectors. Regardless as to whether the pressure is adequate or inadequate, move to step 3.

3) Open your lid, and have a friend spray a small amount of starter fluid into the intake manifold as you are cranking the starter; if the engine starts up momentarily and then dies, you know your spark and compression are good - and that the fuel is the culprit. If not, you're in the spark and compression realm - narrow down the problem from there.

The key is to wait patiently for the one time that it will turn over but not start, and pinpoint why it won't start. I can imagine the dealer's frustration when you bring a problem to him that happens "one out of fifty times."

I said this up top but I disagree with using starting fluid for any form of diagnosis or mechanical issue. Reason being, after the engine has been running the underhood temperatures are very hot, so mix that with extremely flammable ether and it's not going to be pretty. Just diagnose it correctly and check for spark using a spark tester like I suggested. Not being a jerk but I've seen fires combined with blowing intakes up as a result of flooding the intake tract. I was taught in school that it has no place in the automotive industry and to leave it to the lawn mower industry.

Anybody have any other ideas??? Any help is greatly appreciated...

Anybody have any other ideas??? Any help is greatly appreciated...

Have you diagnosed it or followed anyones advice? Its not a new car and it could be anything and that's why you need to track it down. At least give us some clue as to what it's missing like fuel, spark, etc.

Have you diagnosed it or followed anyones advice? Its not a new car and it could be anything and that's why you need to track it down. At least give us some clue as to what it's missing like fuel, spark, etc.


Original shop I took it to replaced the fuel filter, tested the fuel pump and said the pressure was @55psi consistently, and couldn't figure out why it sometimes didn't start. Told me it was the VATS system, and that he didn't have the software to do it. Took it to JBA, who I paid to disable the VATS. Had the same problem a week later, so I took it to CMS and they checked it out and said VATS was indeed disabled. From there, took it to another shop that said it was most likely the fuel pump, then when the car started, they tested it again and said it was the crankshaft position sensor. Had them replace that, then the shop called the next morning and said the car was having the same problem. They told me it HAD to be the car's "ignition security system," and that somebody must have messed up when disabling it. Then I was told to go with the relays, so I replaced both fuel pump relays at auto zone yesterdya, all seemed well, then it didn't start at night when I was leaving basketball.


Today on the highway, the car died. I was in sixth, felt the engine just turn off, but I still had power steering, brakes, etc. Downshifted to fourth, the RPM's jumped up a bit but the when I gave it gas nothing happened, and the car came to a stop. Luckily it started right up, and I got off the highway and took backroads back home.


Hope that helps at all...

Original shop I took it to replaced the fuel filter, tested the fuel pump and said the pressure was @55psi consistently, and couldn't figure out why it sometimes didn't start. Told me it was the VATS system, and that he didn't have the software to do it. Took it to JBA, who I paid to disable the VATS. Had the same problem a week later, so I took it to CMS and they checked it out and said VATS was indeed disabled. From there, took it to another shop that said it was most likely the fuel pump, then when the car started, they tested it again and said it was the crankshaft position sensor. Had them replace that, then the shop called the next morning and said the car was having the same problem. They told me it HAD to be the car's "ignition security system," and that somebody must have messed up when disabling it. Then I was told to go with the relays, so I replaced both fuel pump relays at auto zone yesterdya, all seemed well, then it didn't start at night when I was leaving basketball.


Today on the highway, the car died. I was in sixth, felt the engine just turn off, but I still had power steering, brakes, etc. Downshifted to fourth, the RPM's jumped up a bit but the when I gave it gas nothing happened, and the car came to a stop. Luckily it started right up, and I got off the highway and took backroads back home.


Hope that helps at all...

If the shops couldn't figure it out then why would you trust what they say. You need to start from ground zero and forget what's been done to the car. Rediagnose it yourself or take it to a qualified person who knows what their doing. Simply take it to a dealership and let them figure out what's wrong with the car. If it didn't fix the car why didn't you take it back any one of the shops that you paid? I think every shop is just blaming another shop to compensate for their lack of knowledge. Like I stated before put a fuel pressure gauge on the car and route it up through the cowl and tape it to the windshield. Leave it there until it dies again and watch to see if the fuel pressure falls. If it doesn't than that gets us headed in the right direction or at least eliminates a huge part of the equation. It's going to require someone to get their hands dirty to find the problem and fix it right the first time. I get this type of situation on a daily basis where a shop put 500 parts on it and some hack mechanic wants to explain to me what he thinks is wrong with it. I don't even listen and don't even care because if someone couldn't figure it out then apparently they overlooked something. Most shops have the ability to bypass the VATS with either a VATS box or a resistor and can easily diagnose a VATS problem. Go to a good shop and stay with a good shop until the car is fixed is my best advice.

:usa:Hi,
sorry to hear of your problem. I would try and obtain a good tech/not a parts replacer. Check the cables and grounds on battery and starter. I have seen some that needed a washer to make proper contact on battery. Check for open circuit with volt meter. Secure all grounds and make sure battery has proper voltage....on occasion the plates in the battery can ground at random creating like issue......wishing you the best and keep your chin up!!!!!jim

Hopefully it was the relays. As a precautionary measure, maybe put a fuel pressure gauge and some starter fluid in the garage next to the car, and in the event that the problem emerges again, you can do some very simple troubleshooting.

1) Turn the ignition off and back on. Listen for the fuel pump. If it primes for two seconds, go onto step 2. If not, check the fuel pump relays (which you've already done at this point), in addition to the fuel pump fuse.

2) Turn the ignition on and test the fuel pressure at the rail. This will give you some detail on the problem, but will not pinpoint it exactly. It'll let you know if the fuel is getting from the pump, through the filter, and into the injectors. Regardless as to whether the pressure is adequate or inadequate, move to step 3.

3) Open your lid, and have a friend spray a small amount of starter fluid into the intake manifold as you are cranking the starter; if the engine starts up momentarily and then dies, you know your spark and compression are good - and that the fuel is the culprit. If not, you're in the spark and compression realm - narrow down the problem from there.

The key is to wait patiently for the one time that it will turn over but not start, and pinpoint why it won't start. I can imagine the dealer's frustration when you bring a problem to him that happens "one out of fifty times."


I'll try and give this a shot the next time it gives me a problem at home and I can test it...with the lighter fluid, should I be doing it only when the car is cold? Or will it not matter...

I said this up top but I disagree with using starting fluid for any form of diagnosis or mechanical issue. Reason being, after the engine has been running the underhood temperatures are very hot, so mix that with extremely flammable ether and it's not going to be pretty. Just diagnose it correctly and check for spark using a spark tester like I suggested. Not being a jerk but I've seen fires combined with blowing intakes up as a result of flooding the intake tract. I was taught in school that it has no place in the automotive industry and to leave it to the lawn mower industry.

I think it's a great tool if the engine is cold.

I'll try and give this a shot the next time it gives me a problem at home and I can test it...with the lighter fluid, should I be doing it only when the car is cold? Or will it not matter...

Thus, only when the car is cold. It sounds like your fuel pump is just randomly dying at this point? Intermittent fuel pump that's dying on the highway, but working normally for the most part. We need to narrow it down to whether it's an electrical problem with the pump, or whether the pump is going bad and/or it's clogged with crud.

As a mechanic I will tell you there is a lot of shops out there that just throw parts @ cars. They are usually less knowledgeable.
But for the ones that are decent these intermittant failures CAN be hard to find.
That & they might not be a profitable job for them either.
No one likes spend countless hours trying to guess what the cars doing when a failure is intermittant. It will be easier to find will it's occuring.
That's why some people run into issues. Comminication is key here.

Now as for your car. Does the SES light come on in the dash after the no start?
It should be on & stay on when the key is on engine not started.
Is there anything noticable not working when it doesn't start?
Like the cluster, radio, day time lamps anything to help hone in on the issue.
If you get into a habit when you turn the key on (radio fan etc off). You can hear the fuel pump cycle on for 2 seconds. Just key on without cranking the engine.
That will also be helpful to know. All though if you can get a decent shop out there they could current ramp your pump with a DSO & an inductive amp clamp to check it's health.

I have also ran into relay issues. In the shop & on my own vehicle.
Did you have the ignition relay replaced in the underhood relay center?

If it does occur again see if you can do some quick checking to note any abnormalities. It might be difficult to catch it long enough for you to check for spark, fuel pressure etc... I dont know your abilities or equiptment on hand.
A little observance here on your part can go a long way to solving your issue.

Check your connections to your ecm, I would even say to disconnect them and clean them with some electrical contact cleaner and re-install and re-torque them. I belive the torque spec is posted on the connector. I've seen codensation build up in the connectors and cause all kind of weird stuff including stalls for no reason.

As a mechanic I will tell you there is a lot of shops out there that just throw parts @ cars. They are usually less knowledgeable.
But for the ones that are decent these intermittant failures CAN be hard to find.
That & they might not be a profitable job for them either.
No one likes spend countless hours trying to guess what the cars doing when a failure is intermittant. It will be easier to find will it's occuring.
That's why some people run into issues. Comminication is key here.

Now as for your car. Does the SES light come on in the dash after the no start?
It should be on & stay on when the key is on engine not started.
Is there anything noticable not working when it doesn't start?
Like the cluster, radio, day time lamps anything to help hone in on the issue.
If you get into a habit when you turn the key on (radio fan etc off). You can hear the fuel pump cycle on for 2 seconds. Just key on without cranking the engine.
That will also be helpful to know. All though if you can get a decent shop out there they could current ramp your pump with a DSO & an inductive amp clamp to check it's health.

I have also ran into relay issues. In the shop & on my own vehicle.
Did you have the ignition relay replaced in the underhood relay center?

If it does occur again see if you can do some quick checking to note any abnormalities. It might be difficult to catch it long enough for you to check for spark, fuel pressure etc... I dont know your abilities or equiptment on hand.
A little observance here on your part can go a long way to solving your issue.


^I def agree with this!^ i am a auto mechanic also.. only age 20 but im ASE certified in 4 out of the 8 categories, going to be taking the other 4 tests very soon..

As a mechanic I will tell you there is a lot of shops out there that just throw parts @ cars. They are usually less knowledgeable.
But for the ones that are decent these intermittant failures CAN be hard to find.
That & they might not be a profitable job for them either.
No one likes spend countless hours trying to guess what the cars doing when a failure is intermittant. It will be easier to find will it's occuring.
That's why some people run into issues. Comminication is key here.

Now as for your car. Does the SES light come on in the dash after the no start?
It should be on & stay on when the key is on engine not started.
Is there anything noticable not working when it doesn't start?
Like the cluster, radio, day time lamps anything to help hone in on the issue.
If you get into a habit when you turn the key on (radio fan etc off). You can hear the fuel pump cycle on for 2 seconds. Just key on without cranking the engine.
That will also be helpful to know. All though if you can get a decent shop out there they could current ramp your pump with a DSO & an inductive amp clamp to check it's health.

I have also ran into relay issues. In the shop & on my own vehicle.
Did you have the ignition relay replaced in the underhood relay center?

If it does occur again see if you can do some quick checking to note any abnormalities. It might be difficult to catch it long enough for you to check for spark, fuel pressure etc... I dont know your abilities or equiptment on hand.
A little observance here on your part can go a long way to solving your issue.



Thanks for your help, sorry for the lag.Little update, dunno if it helps.

The last time the car didn't start, the SES light was on. Today, when I was driving on my way home, I could feel power loss in sixth gear after driving around for about fifteen minutes it felt like, then when I downshifted to go up the hill to my house, the car noticeably lost power, regained it and there was some backfire with the exhaust. I got it home and drove it around the neighborhood to see if it would keep acting up, and it just felt like there was uneven amounts of fuel getting to the engine (but that's just a guess.)

As for other things not working when the car isn't starting, doens't seem to be the case. Radio, dash, lights are usually all on and fine when it doesn't.

I appreciate the help, I put a video camera in the car so the next time it doesn't start I can at least post a vid and hopefully get some help out of that.

That made me think it was the fuel injectors, but I don't think that would explain that the problem doesn't happen that often.

At this point, I see everyone has given you some pretty solid advice. However, here is something that is also free that you can try: Next time you are cruising, grab your key and move it up and down (dont turn the ignition off, just push up and down on the key). You may have a failing ignition switch and that can often times get it to act up. Worth a shot at this point.

Took the car to Seaside Auto Repair (GM dealer's service department) in Miramar.


After three days of not hearing anythign, I t was told that "when we took the car out the first time, it was throwing five codes....when we flashed it and took it out again, it was throwing eight codes."

One of them was engine misfire, the others he said he wasn't even that familiar with. He said based on what he was seeing, he woudl recommend replacing the PCU, which would cost $420. He also said there was a code saying that the MAF wasn't working right, and based on the car throwing so many codes and even more after they took it back out again, that it's more likely a bad "computer" than anything else.

Then he said they also recommended replacing all the spark plugs and wires, which after parts and labor would cost around $400 "because of the labor."

I told him I'd take the weekend to think about it...(they're closed on Saturdays and Sundays)

do your own plug change .maybe you can find a PCU(ECM) on this forum for cheaper.clean the MAF and find out if one of the codes was a bad cam sensor.

DobsZ28 -

I can't speak to the "driving down the road and the engine stutters / loses power" but as for the intermittent starting issues, find your VATS relay - behind and to the right of the glove box, and also BEHIND a piece of sheetmetal (!!!) - and find the very small ground BLK/RED ground wire; wiggle this wire (at the relay connector) while trying to start your car. If the ground wire is loose within the body of the relay connector, you may have found your intermittent No-start issue. (Ask me how I know.)

DobsZ28 -

I can't speak to the "driving down the road and the engine stutters / loses power" but as for the intermittent starting issues, find your VATS relay - behind and to the right of the glove box, and also BEHIND a piece of sheetmetal (!!!) - and find the very small ground BLK/RED ground wire; wiggle this wire (at the relay connector) while trying to start your car. If the ground wire is loose within the body of the relay connector, you may have found your intermittent No-start issue. (Ask me how I know.)


Thanks for the help -- would this make a difference if i had the VATS removed from the car through a tune? Because that was one of the first things that I had a shop do when the issue started happening...

I assume you had similar problems?

Just a little update --


The car has been at the shop for aweek now. At first they told me to replace the PCU and sparkplugs/wires. They also recommended a fuel induction cleaning service + MAF cleaning.

Approved the MAF cleaning and the induction service (cars got 72K miles on it, figured it might as well be time to have those cleaned up), got a call back from the shop. They said now that 6 of the 8 codes were no longer on, but there were two new ones, AND the car was driving worse now.

The new code is for an O2 sensor and a misfire on cyllinder 3 and 4. They aagain recommended spark plugs/wires for $400 + $197 for the O2 sensor replacement. I told them no thanks on both, as I'm going to take it to a local place that will do it for half the price, but my question is, if they cleaned the MAF sensor, could that have fucked things up? They're saying my SES light is now constantly on, a problem I never had before...

Also, in terms of the cyllinder misfire, would that cause the car to kind of jerk around during acceleration? And will spark plugs/wires really be a probable solution?

Also, connections to the fuse blocks were checked and okay'd by their technician.


As for the 8 codes the car WAS throwing, they were:


P0102
P0200
P0300
P0443
P0449
P0645
P0801
P0803

P0102 - Mass Air Flow (MAF) Circuit Low Frequency
P0200 - Injector Control Circuit Malfunction
P0300 - Misfire detected
P0443 - EVAP Purge Solenoid Valve 1 Control CKT
P0449 - EVAP Vent Solenoid Control Circuit
P0645 - A/C Clutch Relay Control Circuit
P0801 - Reverse Inhibit Control Circuit Malfunction
P0803 - 1-4 Upshift Solenoid Control Circuit Malfuncion

Quite a varied amount of stuff there. Might want to double check the PCM connectors as already suggested as well as double check the grounds.

First off check all your grounds. To many intermittent issues going on here. If you need the locations of the grounds I can give them to you.

Also make sure the battery terminals are nice and tight and the threads are not stripped in any way.

As I was reading about it losing power, all I can think of would be o2's and fuel pump.

Also, connections to the fuse blocks were checked and okay'd by their technician.


As for the 8 codes the car WAS throwing, they were:


P0102
P0200
P0300
P0443
P0449
P0645
P0801
P0803

It's crazy that these technicians can't figure this out and I wish you were closer because this is textbook easy. All of these DTC's relate directly to each other and shouldn't be hard to figure out. To make a long story short and so I don't end up explaining each circuit individually I will say that the circuits funnel up to three fuses (ENG CTRL, INJ 1, and Ingition 1). The three fuses are all fed by the Ignition 1 Relay Circuit which I believe is the culprit considering it's setting all of these DTC's. This is the cause of the shutting off because it's shutting down an entire bank of fuel injectors. Now in saying that some more diagnosis needs to be done to determine what exactly is happening with the Ignition Relay Circuit. For instance, is it loosing power from the ignition switch, is it loosing the ignition relay ground, etc? Really, if they can't trace this drive to another dealership. If I can diagnose this over the internet they should be able to do it in person.

Not to oversimplify things, but try going back to basics. An engine needs three things to start: fuel, air, spark. The next time it's not starting but turning over, disconnect the fuel line at the fuel rail by your intake manifold. VERIFY that fuel is or is not being pumped.

If fuel is spilling out when you're cranking, verify that you are getting spark. If fuel is not spilling out, then you've narrowed it down to fuel delivery.

My 93 Camaro did this a few months ago. It would turn over and not start. Died in traffic under normal driving conditions. The wire that goes from the fuel pump relay through the body of the car to the fuel pump (the grey wire) had frayed somewhere in the body of the car. I ran a new wire from the fuel pump relay directly to the fuel pump, and now I can drive the car. Once I disconnected the fuel line at the fuel rail and found out that I was not getting fuel, I was able to focus on the fuel system. I tested my fuel pump and verified that it was working. Then I verified that my fuel pump relay itself was working. So the problem lay in between the two.

So verify these three things:

• Fuel
• Spark
• Air

and it will bring you closer to your problem.

Grab a spare computer and have it flashed with your program. Im betting its the computer or the ignition relay like Turbostang said.

Sometimes when you get a intermittent problem like this...the only thing left is to throw parts at it. You cant very well troubleshoot it if it isnt broke, only when it is acting up.

Ive seen where cars/trucks do crazy stuff especially improper transmission operation....its the computer. Alot of times a reflash fixes it. The program gets corrupted and causes havoc.

If it makes you feel any better, I'm having the exact same problem on my Firehawk. I've only gone so far as to swap the relays around and take them apart to make sure they are contacting correctly. Also FYI the relays can go in both ways, they are wired to use opposite corners so either of the 2 ways they fit in will work. My car has yet to leave me "sit," but has cut out on the highway for like 20 seconds, and does the exact same starting issue you have. I replaced the fuel pump recently, so I highly doubt that is the issue for me(it's silent, I never hear it run).

I'm thinking maybe loose ground somewhere. It's slightly frustrating.

ive got a 94 z28 doing the same thing. it gives me trouble. randomly doesnt start. took it to a shop and of course it ran fine for them but when i was driving it home from the shop, it stalled. it has stalled on me a few times before that and when im driving in 4th (auto trans) it gets these random points where it feels like the engine skips a beat. but its all intermittent.

anyway last time i had trouble with it starting, i wiggled the fuses inside the dash and after that it started up no problem. could be an ignition relay, short or even a bad ground somewhere.