1999 vortec engine trouble

[imiceman44]

So I just picked up this 1999 gmc van with the 5.7 vortec engine.
It starts and dies in 2 seconds.
I can hear the pump priming and then I start it and it dies.
My first thought is probably a plugged fuel filter as soon as it starts pressure drops because of the plugged filter so whether it's the problem or not, it has been sitting for 3 years it deserves a filter.
I thought maybe the oil pressure switch but the oil pressure does go up.
What do you guys think?
I will do the filter in the morning and let you know if it's solved.
Let's hear them.

 

[Justin V]

Look into MAP sensor and MAF sensor.

If the computer doesn't see the vacuum (MAP) and/or airflow (MAF), then it won't keep supplying fuel after the starter circuit is released.

Much more likely to be MAP, it should still run without a MAF, albeit like shizz....

 

[imiceman44]

Look into MAP sensor and MAF sensor.

If the computer doesn't see the vacuum (MAP) and/or airflow (MAF), then it won't keep supplying fuel after the starter circuit is released.

Much more likely to be MAP, it should still run without a MAF, albeit like shizz....

Ok I will look at that .
Could possibly be a rat that ate the wire

 

[TreeFarm]

Does the truck have VATS? Is there a chip in the key? Those keys/ignitions are known to be crap and cause it to shut down injectors after a few seconds. There is an easy bypass, Figure out the resistance of your key. Buy a resistor that size, and install it in the wire under the dash.

 

[ZooMad75]

Does the truck have VATS? Is there a chip in the key? Those keys/ignitions are known to be crap and cause it to shut down injectors after a few seconds. There is an easy bypass, Figure out the resistance of your key. Buy a resistor that size, and install it in the wire under the dash.

A 1999 will have a Passlock security system instead of VATS. Big difference is the chip isn't in the key but in the lock cylinder. The chip is rotated past a hall effect switch to "see" the value when the lock is rotated. But if there is an issue with the passlock system the engine will initially start and then stall within 2 seconds because the PCM shut off the fuel and spark.

 

[imiceman44]

No

 

[imiceman44]

A 1999 will have a Passlock security system instead of VATS. Big difference is the chip isn't in the key but in the lock cylinder. The chip is rotated past a hall effect switch to "see" the value when the lock is rotated. But if there is an issue with the passlock system the engine will initially start and then stall within 2 seconds because the PCM shut off the fuel and spark.

So if that is the case what is the solution?
Someone already suggested that, the seller's brother

 

[sweetk30]

vortecs are sensitive to fuel pressure . they need 55-59psi if i recall . if below the min spec lots of times they wont run worth a crap or stall out .

 

[imiceman44]

I didn't get to it yet but I will be doing the fuel filter.
But so far it feels exactly like zoo says

 

[diesel4me]

I wonder if the electric fuel pump has a rubber hose connecting it to the sending unit ?...seems a lot of K5's that do had that hose split open and cause issues like this...filling the tank right to the top may mask the symptom and let it run longer till the fuel level drops below the hose connection..

I have seen the fuel feed pipes on sending units rust thru on the inside of the tank and the engine stalls once the fuel level is lower than the hole in the feed pipe on a few vehicles my friend replaced fuel pumps on at his shop..

 

[Blue85]

2 seconds makes me think the fuel pump is only priming. This is obvious if you have a fuel pressure gauge on it or a voltmeter on the pump. There were some GMs with dual-speed fuel pumps and a dead resistor gives you the couple seconds of run-time symptom. You would get the same effect if the fuel pump relay switches between 2 sources. Would only take a minute to put a jumper wire to replace the relay. Keep in mind there is often more than one oil pressure sensor/switch, so a good dash (or scantool) pressure reading doesn't mean the fuel pump will stay powered.

 

[ZooMad75]

So if that is the case what is the solution?
Someone already suggested that, the seller's brother

If this was a passlock situation it would be setting codes in the vcm. You would have a p1626 set for theft deterrent fuel enable signal not received.

If you don't have theft deterrent codes it's time to look elsewhere. The passlock system will set codes when there was a a fault.

 

[6.2Blazer]

I can see the parts cannon getting loaded and ready to fire! For those of you that don't know what that means, it is the process of "fixing" a vehicle by randomly throwing parts at it based on what somebody's second cousin's uncle says is the issue. Instead of recommending what part is bad, what about start recommending diagnostic procedures. Start with the basics of fuel and spark.

- hook up a fuel pressure gauge and see what pressures you are getting......when you first cycle the key does the pressure go up to the right level, what happens when you start it and then dies...does pressure drop right before it dies
- check power to the fuel pump.....if you have power with the key on and then the voltage goes away that means either the ECM is cutting power to the pump or a bad wire (but that would be more intermittent)
- check power to ignition.....I'm sure there is a control wire or something you can tap into and see if power is being cut to the ignition
- unplug each sensor one at a time and see if it makes a difference......often the ECM's have default strategies that will allow the engines to still run if they completely lose a signal from a sensor....there is a difference between a sensor giving a bad signal versus no signal at all, the ECM can often compensate for no signal at all, but if a sensor is telling it something completely wrong it can cause issues...also, many sensors are not used during initial start up when the engine is cold (i.e. O2 sensors don't come into play into the engine is warmed up).

If you don't have a scanner capable of reading live data, go get one. Even a cheap Harbor Freight version can give you basic information. Also start reading up on diagnostic procedures and maybe invest in a factory service manual. In the end, just don't start throwing parts and band-aids at it. I've actually been in situations where it took longer to figure out the real problem because somebody had started changing stuff around and you had to get everything back to stock or at least properly functioning before being able to isolate the original problem. I've seen people thrown in different heat range spark plugs, change O2 sensor locations, "delete" emissions sensors, re-run wires, etc... that often cause there own issues.

 

[imiceman44]

If this was a passlock situation it would be setting codes in the vcm. You would have a p1626 set for theft deterrent fuel enable signal not received.

If you don't have theft deterrent codes it's time to look elsewhere. The passlock system will set codes when there was a a fault.

Got it going.
Did 10 minutes on 5 seconds off, learning method, it took 5 cycles and finally cleared.
Now it's running decent for 3 year old gas but has a miss, code shows cylinder 4.
Wires seem fine.
When it's cooler I will check the spark plug and the cap.

 

[imiceman44]

I can see the parts cannon getting loaded and ready to fire! For those of you that don't know what that means, it is the process of "fixing" a vehicle by randomly throwing parts at it based on what somebody's second cousin's uncle says is the issue. Instead of recommending what part is bad, what about start recommending diagnostic procedures. Start with the basics of fuel and spark.

- hook up a fuel pressure gauge and see what pressures you are getting......when you first cycle the key does the pressure go up to the right level, what happens when you start it and then dies...does pressure drop right before it dies
- check power to the fuel pump.....if you have power with the key on and then the voltage goes away that means either the ECM is cutting power to the pump or a bad wire (but that would be more intermittent)
- check power to ignition.....I'm sure there is a control wire or something you can tap into and see if power is being cut to the ignition
- unplug each sensor one at a time and see if it makes a difference......often the ECM's have default strategies that will allow the engines to still run if they completely lose a signal from a sensor....there is a difference between a sensor giving a bad signal versus no signal at all, the ECM can often compensate for no signal at all, but if a sensor is telling it something completely wrong it can cause issues...also, many sensors are not used during initial start up when the engine is cold (i.e. O2 sensors don't come into play into the engine is warmed up).

If you don't have a scanner capable of reading live data, go get one. Even a cheap Harbor Freight version can give you basic information. Also start reading up on diagnostic procedures and maybe invest in a factory service manual. In the end, just don't start throwing parts and band-aids at it. I've actually been in situations where it took longer to figure out the real problem because somebody had started changing stuff around and you had to get everything back to stock or at least properly functioning before being able to isolate the original problem. I've seen people thrown in different heat range spark plugs, change O2 sensor locations, "delete" emissions sensors, re-run wires, etc... that often cause there own issues.

I don't use that method.
I have been around the block a few times.
If don't find the right diagnosis and don't do anything.
Zoo described the exact symptoms so I went down the rabbit hole and read and watched videos, then started with the easiest thing first and it worked and now I know my options if it comes back and I don't want to deal with it, there's a permanent solution, which I will need when I put that engine in my 89 suburban

 

[sweetk30]

96-03 vortecs v8 and later v6 had dist cap moisture problems and lots of times the cap was heavy corrosion on the terminals .

also ACdelco plugs exactly for these vehicles of they can miss .

 

[Wes Harden]

What @sweetk30 said. keep a new cap and rotor in truck at all times, you will probably change it once or twice a year.

 

[sweetk30]

also t-10 and t-15 if i recall for the cap and rotor screws .

and BE CAREFULL with cap screws in the plastic dist housing . the LOVE to break the ears off . and do NOT use a reman dist with glued on ears they suck worse .

 

[imiceman44]

also t-10 and t-15 if i recall for the cap and rotor screws .

and BE CAREFULL with cap screws in the plastic dist housing . the LOVE to break the ears off . and do NOT use a reman dist with glued on ears they suck worse .

I know about that I just replaced one on the suburban, it had the broken ear and broken ignition plug.
I think we found our problem. Rusty no 4 plug.
A new set should be good for it.

 

[imiceman44]

Rusted plug and the other one next to it.
Pictures are blurry but it is obvious enough