Engine cranks and fires then dies, PLEASE HELP

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Burban117

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Here's the situation.

1998 Chevy Suburban K1500 350 Vortec
I have no idea what happened, it drove it home and parked it, tried to drive to work the next morning and it would crank and fire and run for all of 1 second or too before dying.

What I Know
Security light is on but not flashing when it dies. I've tried the Passlock reprogram thing but it doesn't seem to be the issue although this is the first time I've heard of it.Fuel pressure is 60ish when I turn the key to the on position, drops when I turn the key but pops back up to 60ish when its fires. I have spark on all cylinders. All my fuses are good.

What I've replaced in an attempt to fix the issue
New Cap, Rotor, Plugs and Wires, ignition control module, ignition coil. New Map sensor and Mass airflow. New idle air valve.

It still just seems to fire then die and I'm tired of throwing parts at it to fix it and I need my vehicle back
 

HotWheelsBurban

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Here's the situation.

1998 Chevy Suburban K1500 350 Vortec
I have no idea what happened, it drove it home and parked it, tried to drive to work the next morning and it would crank and fire and run for all of 1 second or too before dying.

What I Know
Security light is on but not flashing when it dies. I've tried the Passlock reprogram thing but it doesn't seem to be the issue although this is the first time I've heard of it.Fuel pressure is 60ish when I turn the key to the on position, drops when I turn the key but pops back up to 60ish when its fires. I have spark on all cylinders. All my fuses are good.

What I've replaced in an attempt to fix the issue
New Cap, Rotor, Plugs and Wires, ignition control module, ignition coil. New Map sensor and Mass airflow. New idle air valve.

It still just seems to fire then die and I'm tired of throwing parts at it to fix it and I need my vehicle back
How new are the crankshaft position sensor, throttle position sensor and fuel pump relay? Try switching the relay with another one that has the same pins.
I had this same problem with my 99 Burb last year. Loaded the parts cannon and replaced TPS,CPS, rotor with a Blue Streak one, and fuel pump and starter relays, over about 6 months. It would be absolutely perfect for 2 or 3 days, or a week, then wouldn't start and stay running at all. Then it would fire right up and run as it should, like nothing was wrong. This issue is what got me to this forum!
I tried all the "relearn " procedures and some worked great and some didn't. I think that what it was, was that the Passlock module under the dashboard was going out. These are circuit boards and after 20+ years of bouncing around they start coming apart. I've read that they can be resoldered or rebuilt, but that wasn't in my options. What I finally did was find a local speed shop that mainly works on and tunes LS's. Camaros,Vettes,CTS-V's, that sort of thing. They looked askance at my old Burb, but I explained what it was doing and what I wanted done. Basically, I had them tune the Passlock out of the main computer. There's other posts and threads that cover this on here that explain it better. It cost me $250, but it was done in October of last year and the truck starts up great every time now.
One other thing I would suggest: look at all your connections and terminals. Bad grounds and corroded or loose wires have been at the root of many mysterious and troublesome and frustrating electrical problems. My Burb did the "no start when hot" BS in January; turned out to be a loose ignition terminal on the starter solenoid (the small one) and a badly corroded positive cable. If you have to replace the cables, if there's a shop in your area that makes cables (welding or battery shop), that's what I would recommend. The factory style cables are very expensive and hard to find! I had the 8 foot cable that goes from the battery across the fan shroud and down the driver's side inner fender panel to the main computer, for under $12! Would have been over $125 at the parts store and waiting a week for it to come from the east coast.
Not doing that! This is the daily driver and only vehicle for my family, gotta have it back up asap. So I definitely feel your pain on that. There are tricks with resistors and things to bypass the Passlock system, but you have to get into the steering column or under the dashboard.
Thanks for reading my long winded explanation and post, hope this helps with your truck! Post updates on this forum when you get it sorted out!
 

Dropped88

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is there anyway you can scan to see if you have a stored code possibly security related.

im not 100% but depending on fault, the light can be on solid. because your description sounds passlock issue
 

Burban117

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How new are the crankshaft position sensor, throttle position sensor and fuel pump relay? Try switching the relay with another one that has the same pins.
I had this same problem with my 99 Burb last year. Loaded the parts cannon and replaced TPS,CPS, rotor with a Blue Streak one, and fuel pump and starter relays, over about 6 months. It would be absolutely perfect for 2 or 3 days, or a week, then wouldn't start and stay running at all. Then it would fire right up and run as it should, like nothing was wrong. This issue is what got me to this forum!
I tried all the "relearn " procedures and some worked great and some didn't. I think that what it was, was that the Passlock module under the dashboard was going out. These are circuit boards and after 20+ years of bouncing around they start coming apart. I've read that they can be resoldered or rebuilt, but that wasn't in my options. What I finally did was find a local speed shop that mainly works on and tunes LS's. Camaros,Vettes,CTS-V's, that sort of thing. They looked askance at my old Burb, but I explained what it was doing and what I wanted done. Basically, I had them tune the Passlock out of the main computer. There's other posts and threads that cover this on here that explain it better. It cost me $250, but it was done in October of last year and the truck starts up great every time now.
One other thing I would suggest: look at all your connections and terminals. Bad grounds and corroded or loose wires have been at the root of many mysterious and troublesome and frustrating electrical problems. My Burb did the "no start when hot" BS in January; turned out to be a loose ignition terminal on the starter solenoid (the small one) and a badly corroded positive cable. If you have to replace the cables, if there's a shop in your area that makes cables (welding or battery shop), that's what I would recommend. The factory style cables are very expensive and hard to find! I had the 8 foot cable that goes from the battery across the fan shroud and down the driver's side inner fender panel to the main computer, for under $12! Would have been over $125 at the parts store and waiting a week for it to come from the east coast.
Not doing that! This is the daily driver and only vehicle for my family, gotta have it back up asap. So I definitely feel your pain on that. There are tricks with resistors and things to bypass the Passlock system, but you have to get into the steering column or under the dashboard.
Thanks for reading my long winded explanation and post, hope this helps with your truck! Post updates on this forum when you get it sorted out!

No I appreciate long posts. The more brains I can pick and ideas I can look into the better.

Dropped88 seems to think it might be the passlock system too.

At first it seemed like a ignition issue and now it seems like a fuel issue despite getting good pressure so maybe it is a relay or something I'll half to check tomorrow.

I'm not sure if there'd be any stored codes, I can't seem to keep it running long enough fo it to throw a code. I'll try that too though just for geewhiz.

I did a once over on cables and terminals, even changed the battery terminal clamps and stripped back the wires to fresh copper but I will double check. I'm not good with car electrical so any pointers on things to look for let me know.

There's two people saying it could be the passlock and I've done the relearn procedure to no success but I'll do some research maybe I'm missing something

Thanks again for the help
 

HotWheelsBurban

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Does your Burb have any type of aftermarket alarm or security system on it? One of my mechanic friends has a good scan tool, one of the professional tablet models from Snap On, and he scanned my truck a couple years ago.
It always had an intermittent starting problem; my guess now is that the Passlock was already having issues. He told me to take the aftermarket alarm stuff off, that it was interacting badly with the factory stuff. "Arguing with it" was actually the term he used, and now that I know more about how it works, that's an apt description.
One of the times I was successful at getting it started, we took the Burb to an alarm shop close to where we were living then, and their installer took the aftermarket alarm bits out for $20. Worth it to me to have someone who has more experience than me to do this! He and other people have looked at it then and said it looked like kind of a hack job under the dashboard. We bought the truck used in 2013 off a small independent car lot, and they knew nothing of the truck's history. It's actually the second 99 Burb we've had, the prior one was totalled in late 2012 by a drunk driver who ran a red light. Was a decent truck until that point....
 

Ron88

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I would check that I had computer power after the vehicle starts in case its some kind of ignition switch problem. If it is going away due to a faulty ignition switch or even the passcode I would put power to it from another source to see if it keeps running. That's a tough one sorry to be so vague.
 

Burban117

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No aftermarket security system

Quick question since I'm new to this security Passlock system. So my security is on constantly, I've heard that its supposed to flash when the security system has been tripped but mine just stays on all the time

Any thoughts
 

HotWheelsBurban

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Here's a couple of pages from my 99 Burb owners manual. After the tune out, the security light may come on from time to time. As long as the truck starts and doesn't do anything stupid, it doesn't bother me if the light is on. The dashboard lights that concern me are the check engine and the ABS (which is the one I'm dealing with right now. Just have to be cautious about stopping on wet pavement.....got a good bit of rain from Hanna even 250 miles from where it made landfall.

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Burban117

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Ok so my truck barely starts I mean it will run for a second at most then die like it's not getting fuel. But when it dies the security doesn't flash. Its always on from the time I turn the key to the on position to the time I turn it off, whether I try to start it or not. By that description I dont even think the truck is running long enough to even trip the theft protection.
 

Burban117

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Ok so my truck barely starts I mean it will run for a second at most then die like it's not getting fuel. But when it dies the security doesn't flash. Its always on from the time I turn the key to the on position to the time I turn it off, whether I try to start it or not. By that description I dont even think the truck is running long enough to even trip the theft protection.

To clarify it didn't use to do this I would start the truck and within a few seconds the security light would go off like described in the manual but idk I'm familiar with the theft system so its tell but by that description it makes me feel like the theft system isn't the issue.

I'm in the middle of the relearn procedure right now actually after installing a resistor between the orange and yellow wires like in the videos and even now the security light is just solid.
 
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