99 s10 Blazer turns over, but won't start...sometimes.

07-31-2006, 02:16 PM
About a year ago my blazer did not want to start after a bout a 1.5 mile drive...By the time AAA got there, (2 hours later) it started right up no problems. And no problems until a week ago. Last Monday I had the car sitting in the driveway went to go pull it in the garage late at night...did not start...not wanting to mess with it, I just left and went to bed...next morning started right up no problems. But yesterday...i drove it to lunch and tried to start it off and on all afternoon and evening...:banghead: ...I let it sit all night and tried the next day around noon....it started up with no problems. No "check engine" light is on...does not appear to be acting different in anyway. A couple things to note...I'm a volunteer firefighter/paramedic and use my personal vehicle to respond to scenes...so it's not a Sunday afternoon drive kinda car...it takes some abuse. But have had no major problems (minus a new transmission 2 years ago). Also both last week and yesterday have been upwards of 100 degrees outside, however, not the first time this happened a year ago. Also know that it turns over very well, and has no apparent gas odor (maybe that matters, maybe it doesn't just thought i'd mention it)

Any ideas where to start?

Thanks a ton!!

08-01-2006, 11:56 AM
Sounds an awful lot like a "PASSLOCK" security problem. Do you get a flashing security warning light on the dash. If so the fuel pump/injectors gets disabled for 10 minutes.

Whats happening is the ignition switch is not sending the proper code when your key gets inserted. the computer reads this as an attempt to steal the car and locks out the fuel pump/injectors for 10 minutes.

This happened to my 99blazer. It was very intermittant and then got progressivly worse over about a year to the point where it would not start period. I had the ignition switch replaced about 2 years ago and have had no problems since. Read the threads here as there is lots written on the subject.

What I do not recomend is trying to bypass the system. It nearly never works unless you know exactly what you are doing. I'd go with the new switch for sure.

Good Luck

08-01-2006, 02:46 PM
Well, I took you advice and read up on some of the Passlock stuff, it seems that could be the problem by just the nature of it....although, the only thing that makes me think otherwise is the it takes longer than 10 minutes before it restarts. This last time I had the issue, I tried starting it after 8 hours and it did not start, although it started 15 hours after that...so almost 24 hours later...it started. Still sound like it could be a Passlock issue? Maybe just a bad sensor?

Would it hold a code even after it starts and is running okay? I'm afraid if I take it in to have to worked on are they going to tap my wallet looking for the problem??

Called the dealer they want $146 for the Passlock sensor.

08-01-2006, 04:15 PM
Most Blazers don't have anything on the key (my 4 do not) so I would look at the coil or ignition module causing it to always have a low voltage on and overheating it.

08-01-2006, 06:54 PM
How about the fuel pump? I just went through these same symptoms and the problem was the pump. Do you hear the pump whine on the occasions that it won't start?? Mine was intermittent for a week or so then nothing! Do a search on fuel pumps - there's a ton of info on this site.

08-01-2006, 09:46 PM
My 98 does that every once in a great while. It is a PASSLOCK problem on mine. When it doesn't start the SECURITY light will flash. It usually starts after 10 minutes, but a couple times I've had to wait for a couple hours. I'm not sure if it's the PASSLOCK unit itself, or the self-installed remote start system having a voltage issue. I have heard of other GM models with the PASSLOCK having no-start issues also.
Used to be a volly myself, now I'm career. Stay safe. :)

08-02-2006, 12:48 AM
I have a 2000 Blazer with the same problem, and it's the PASSLOCK system.
Sometimes it won't start after 3 or 4 tries. A real pain in the "beep"!!
If it is the Passlock system it will hold a code, mine did.
I haven't fixed mine yet, but it sounds like getting a new ignition switch is the only real fix. But will it start doing it again?

08-02-2006, 09:18 AM
My passlock problem had very similar symptoms. Important to note though is that everytime it would not start the security light will flash. After 10 minutes though the light stops flashing and you get a chance at starting. If it detects the same fault then your into the 10 minute cycle once again.

Also, I had no fault codes directing me to a problem with the switch.

I had internittant problems where sometimes it would start right away and sometimes it took between an hour and longer, sometimes overnight to start. The problem would go away for sometimes a week or a month and then its back again.

When I tried to start, the engine would turn over, and start for a fraction of a second and then it was just cranking.

I have had no problems in 2 years since changing the ignition switch.

Good Luck

08-02-2006, 10:13 AM
That sounds exaclty like that might be the problem then...I haven't had any issues with it since the other day. So...maybe i'll wait till it happens again and pay attention to the security light and see what that's doing.

Is a ignition switch fairly simple to replace? I assume it's in the stearing column??


08-02-2006, 02:15 PM
Not really sure whats involved, I took mine to the dealer ... It wasn't too pricey but at the time I was desparate to get it fixed as it would not start at all regardless of how long I waited.

I would advise fixing it asap as it will likely break at the worst possible time and location. Mine did once ... $30 cab fare later and the next morning after biking back 10 miles it started right up.

If you do it yourself, you will likely find zero info in the Chiltons or Hayes manuals as they leave this stuff out. What to pay attention to is the disabling of the airbag components. This involves pulling the right fuse and disconnecting the electric connection under the dash. If I'm not mistaken the connector is dedicated to the airbag system and is bright yellow. You must first pull a pin on the side of the connector before it comes apart. I took quite a while to figure the disconnect part out when I did it once and I'm sure you will experience the same thing ... I don't remember much about the process of getting it separated but its not exactly straight forward.

If you ever do more work in this area like pulling the dash out ( to say fix a heater core) there are other connectors just like this one for the passenger side air bags.

A last word ... If it were me I would leave this one to a dealer. Getting the thing right with the ability to send codes to the computer and such is in my mind black magic. If it goes bad you are "sol" and it will not start period. Undoing what you did may not work either. There are some threads that describe this complaint as well. At least with the dealer, some sort of warranty on the work is provided and it gives you someone to point a finger at if it breaks later on.

Hope it all works out ...

Anyway ... the manuals are very good at telling you how to do this.

08-02-2006, 09:24 PM
*************************UPDATE******************* *****
Well this sucks...

It did it again tonight...I watched for the security light to blink but it did not, it shut off after about 2-3 seconds with the key in the run position.

I typically hear what i'll describe as a small electric moter making a humming type sound coming from more of rear of vehicle every time I turn the key to the run position just right prior to the starting position. I do not hear that sound now...If the ignition module was bad would that cause other things to not do what they should??? Why else would I not hear that...or better question...anyone know what that is??

Well, I'm off to go see if it will start...if I can find a ride.


08-02-2006, 09:58 PM
Fuel pump is shot.

08-03-2006, 07:18 AM
Fuel pump has my vote now too!!!
Without jumping to a solution too soon, the evidence does tend to point in this direction.
Wouldn't a faulty fuel pump provide a code and a check engine light?

08-03-2006, 09:03 AM
See post #5

08-03-2006, 09:19 AM
Well....I got frustrated enough to take it in to the shop. I dropped it off this morning, said he might not get to it till later...so i'll post what I find out today or tomorrow.


08-03-2006, 11:39 AM
I also have a 99 blazer sitting in my drive way.

I never thought about the security light.
What it did was this:
about 3 weeks ago, I noticed it taking longer and longer to crank. It would sometimes sputter but never "catch". when it does catch, it runs fine and "hot" starting is fairly easy. The problem is when it sits for any length of time. When I turn the Key, I can hear the fuel pump whining. over the last few days, it took longer and longer to get it started. I Have seen the security light blinking, but did not know that it was useless to try to start with this on.

I have changed the fuel filter and the sparkplugs. I also added some injector cleaner. Now it just cranks. I can hear the fuel pump operate for a few seconds, then I hear something that sounds like pressure bleeding back through the system. Could this be fuel pressure passing through a check valve and returning to the tank?

Any ideas what might be wrong?

08-03-2006, 09:29 PM
Go with the symptoms:

First watch the security light. If it flashes leave the ignition in the on position. The light should flash for 10 minutes ... exactly. After 10 minutes the light will go out (Even if there is still something wrong with your switch). Do not attempt to start the car before the light goes off or it will just kick off another 10 minute interval. Attempt to start the car again and it may start, or it may sputter almost catch and start another security cycle if it detects a bad code.

Either way a new ignition switch is required

The car actually turns on the injectors and fuel pump for a brief moment until the bad code comes along. This is why the ignition will almost catch for a second and then crank. It is using up any fuel that made it into the system.

If there is no problem with the security lamp then you'll need to look further. Engine light, trouble codes etc. Remember to look for the symptoms and diagnose based upon what you know. Fuel pump has been changed so that candidate is less likely.... and so on.

Best of luck and let us know how it turns out.

08-04-2006, 11:34 AM
:banghead: Seems like it is fuel pump time for Blazers, got to replace the one on my '99 as soon as I get my son's '01 Hoe out of the garage slapping on some brake pads today.

08-04-2006, 04:10 PM
A guy from a Napa garage told me yesterday that I should try spraying carb cleaner into the Throttle body and scrub the inside with an old toothbrush. he suspects that the injector cleaner worked through and loosened some stuff that is blocking the fuel from entering the throttle body. he thinks this because I never had the engine sputter or die on me once it was running. he told me that I should see lots of balck junk in there, which I do see.

I do suspect that switch though. The Carb cleaner is a cheap fix, so I'll try it first. what have I got to lose? I'll cross my fingers.

I bought this thing for $3500 with 105k miles on it. I like it pretty well, but I did have to replace a wheel bearing.


08-04-2006, 04:21 PM
The throttle body is not where the fuel enters. It is where the air enters.

If you want, remove and, clean and reinstall the IAC valve incase it is the fault which sometimes it is.

08-04-2006, 04:56 PM
what was I thinking? what is the IAC valve? I will look it up in my haynes manual. Beyond spraying, cleaning, and changing easy parts, I am not set up to work on fuel injection. So, some lucky mechanic is probably going to get 5 or 600 bucks out of me somewhere.

08-08-2006, 11:01 AM
Well, I had to wait till Monday to take my car into the shop...

Ended up being the fuel pump...(good call muzzy)...

But I'd like to know who at GM thought they were funny when they put the fuel pump inside the gas tank? It cost me $850 bucks!!!!! How do they sleep at night???

Thanks to everybody who posted info!

08-08-2006, 12:41 PM
Most cars have it inside the gas tank.

08-08-2006, 08:59 PM
Most cars have it inside the gas tank.

I suppose a service access panel would be too much to ask!

I'm not a professional mechanic so I don't know what other auto manufacturers provide for fuel pump replacement including foreign designs; however, imho, not providing repair access is another example of poor design or design by bean counters.

01-25-2015, 05:50 PM
hello everyone, I couldn't help but notice the problems im having with my 99 blazer are explained almost word for word on here and so ive been trying to diagnose the problem by using everyones input but nothing seems to be doing the trick. ive replaced the ignition switch module, the ignition coil and yesterday the ignition switch. I thought I had it with the switch and sure enough it ran for 2 or 3 min and shut right off. now this is driving me nuts because ive had a dealership and two mechanics check it out and nobody seems to have any answers for me. dealership said ignition coil so I changed it and nothing. I read on here ignition switch, changed it and still nothing. the security light flashes when I open the door, when its closed no light, when the key is turned its on and when the truck is running( which is really screwy) the truck runs amazing when it stays running..so my biggest question is what would be the next route and hopefully only route I need to go next? I would greatly appreciate some good advice on this and thank you for reading!!

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