Weird intermittent starting problem...

[yoshisushi]

1998 1500 4.3 2WD Auto (Reg Cab)

Hello all,
I have an intermittent problem and I’m not sure where to begin troubleshooting. Basically on some days (it appears random) the truck will not start, most other days it starts fine.

I can hear the fuel pump run while I’m cranking the engine. Sometimes the engine will sputter a little bit but it doesn’t start. The funny thing is it starts fine later that day or the next day. Usually the check engine light comes on the day following the truck not starting but goes away the day after that. I live in the North East and it’s wintertime here and the thought of moisture being the problem is in my head. I do recall this problem happening once or twice in the summer when it rained heavily.

I’ve had the truck for about 6 months and haven’t done any work to it yet. I don’t know how old the wires and plugs are or the fuel filter. I just bought some AC-Delco wires, cap and a rotor but I haven’t had a chance to replace them yet.

Has anyone seen this before or have any tips??

Thanks in advance!
Rick

[Chevy-SS]

http://www.automotiveforums.com/vbul...ghlight=tamper

Go look at that thread that I started. I had this type of problem and it drove me nuts. I got all kinds of answers and opinions. I ended up fixing it myself for 99 cents. There's a good chance this is your problem too.

[yoshisushi]

Chevy-SS,

Thanks for the response. I read your post. I went through that when I installed my remote starter. I found out that I dont have VATS on my truck. Thanks though.

Today is the day, it decided not to start again. I'm glad I have a beater car as a backup. Well I plan on doing a tuneup this weekend. Cap, rotor, wires, plugs and fuel and air filters. I guess I'll see how things go and post here.

[Chevy-SS]

I suppose I could be wrong here, but I though all GM vehicles used VATS or PASSLOCK. Introduced in 1996, GM has changed the VATS anti theft system to Pass-Lock system. This is a similar device to the VATS system, in that there is a resistor present during the start cycle. However, in the PASSLOCK system, the resistor has been placed inside the ignition switch, instead of the key. This is why you no longer see the resistor actually in the key itself. This is still a theft-deterrent device.

To remotely start a car with this feature, you must bypass the PASSLOCK system. There are two methods of doing so.. The first, is to permanently bypass this system. This is the easiest method for accomplishing your task and this is what I did. The second way, is to temporarily bypass the PASSLOCK, by introducing relays into the system, which retain all of the features of the system, while allowing your remotes start module to bypass it automatically during a remote start cycle.

Bottom line: your '98 truck uses PASSLOCK with the built-in resistor circuit, therefore you could certainly be having the problem that I was. After you get stuck a few more times, if you can't fix it, then do as I did and measure the cranking resistance, buy or make your own resistor of matching ohms and solder in place.

http://www.e-z.net/~iei/vatts.htm

There's a page with instructions. Go to the bottom and use Diagram A. Hope this helps.

Good luck

[Cadillakin'98]

I do believe Chevy-SS is correct about what he is saying about the VATS and Passlock systems. Bottom line is his bottom line is for sure correct. Your '98 has Passlock. Lokk at any wiring schematics for your truck......

[yoshisushi]

Thanks Chevy-SS for the further clarification, I really appreciate it. However I’m worried that since our symptoms don’t closely match that I could be chasing a bad lead but it sounds easy enough that it’s worth a test. I will temporarily put in place the permanent bypass therefore eliminating the PASSLOCK system as the culprit or proving it culpable.

The reason I’m not sure if the PASSLOCK is the problem is because you said your truck would start 10 minutes after the problem occurred, I have to wait 6 – 8 hours, sometimes 24. Also, do you recall if your check engine light ever came on? Mine does and stays on for a day or so after the truck acting up but my “security” light never comes on.

I read in your post that you ran your resistor to an orange/brown wire, is that correct? Is that wire hard to find? The instructions you linked me to seem easy to follow for finding the resistance.


Rick

[yoshisushi]

Found some instructions for the PASSLOCK bypass. Similar to what you did? This is from remote starter instructions for 1998 trucks and whatnot.

[Chevy-SS]

yoshisushi, yes, that is the process for replacing the resistor circuit with a soldered in resistor.

I agree that our symptoms do sound a little different. If the vehicle goes into "Tamper" mode, then I think the wait time is around 8 minutes, for the computer to reset and then you will be able to start the vehicle. Although, it's possible that your resistor circuit is in worse shape than mine was, that is, it rarely produces the correct resistance now.

Your "check engine" light should stay on until it is cleared using the OBDII diagnostic. I don't understand how that could be intermittent. But then again, there's a lot I don't understand with all this electronic stuff.

[J-Ri]

Some lights will stay on even with codes still present in the computer. I dunno why either, but it's not out of the ordinary to see that.

[teamroperhdr]

Seems to me that if it was a passlock problem it would not "sputter" like he says. My best advice it to get the codes read. I had this same problem with my 97 1500 and the code read as failed O2 sensor. I know these are not in a loop until the engine is warmed up but I replaced it and have not had a problem since.

[Chevy-SS]

Originally Posted by teamroperhdr

Seems to me that if it was a passlock problem it would not "sputter" like he says. My best advice it to get the codes read. I had this same problem with my 97 1500 and the code read as failed O2 sensor. I know these are not in a loop until the engine is warmed up but I replaced it and have not had a problem since.

If it is the "Tamper" mode problem then the engine will start very briefly and then immediately die. It will do it this way every single time. About eight minutes later, it will re-set and it may (or may not) start properly.

[teamroperhdr]

Originally Posted by Chevy-SS

If it is the "Tamper" mode problem then the engine will start very briefly and then immediately die. It will do it this way every single time. About eight minutes later, it will re-set and it may (or may not) start properly.

Good to know, thanks for the info SS

[cousincletus]

Yep. Worked on a Tahoe with a bad passlock and the truck would start and immediately die. I would do the tuneup first, get the code read and see what happens.

[91imca]

I do not have remote start but sometimes truck cranks and runs fine but security light comes on, then other times it cranks and goes dead then wait 10 minutes it may crank and stay running or it may crank and go dead , when it cranks and goes dead it will do it every time i have tryed some of the methods mentioned here and none work, i may be doing it wrong or are their other problems with truck, it is a 1998 chevy .

[Chevy-SS]

Originally Posted by 91imca

I do not have remote start but sometimes truck cranks and runs fine but security light comes on, then other times it cranks and goes dead then wait 10 minutes it may crank and stay running or it may crank and go dead , when it cranks and goes dead it will do it every time i have tryed some of the methods mentioned here and none work, i may be doing it wrong or are their other problems with truck, it is a 1998 chevy .

What exactly do you mean when you say "have tried some of the methods mentioned here"? Have you done the permanent security resistor wire bypass? That's where you cut the yellow wire, measure cranking resistance with ohm meter, and then install resistor of similar resistance. Did you do that yet? There is a link to web site explaining in my previous post in this thread, plus there is a small diagram in yoshisushi's post.

In my opinion, you should try the resistor wire bypass. It costs almost nothing to do it and it could solve your problem.

I had similar starting problems with my '98 truck and was getting told to replace fuel pump, computer and all kinds of stuff. I could easily have spent over a thousand dollars chasing this stupid problem, but I got lucky and found a guy at a local service station who had the same issue with his '98 truck. He correctly diagnosed the problem, but he chose to replace the wiring harness, which was a couple hundred bucks, plus a lot of work. I did a little more research based on his diagnosis and found the bypass trick listed on internet.

As I say, this is a very easy thing to do. It's very inexpensive also. I would make this your first task and see if it fixes you.