1999 5.7 starts then dies

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Stepside_fever95

Stepside_fever95

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For the past month or so, i have had an issue cranking in the mornings. Its not every morning, but its enough to tick me off.

What it is doing is that it will fire up, sputter, and all electronics cut out, then the electronics come on and i can crank again. After that sometimes it just dies and nothing comes on. I have cleaned my battery terminals and wires, and the voltage reads 14 like it should. There is no cel either.

This morning i popped my hood while it was running, after it cut out the first time. I noticed that my ac compressor cut off so i went to look at the switch because i thought it was on and it was, so i turned up the fan speed and the truck cut off.

Truck is a 1999 Suburban K1500 5.7
 
99'Subourbon

99'Subourbon

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Sounds like an alternator.

Your battery is used to turn over the engine, but running and current draw is all regulated by the alternator.
 
GL1500

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If the battery were strong enough to crank the engine, shouldn't the engine continue to run until the system voltage drops below below ~10 v? If he has enough amps to restart after it shuts down it seems to me the battery is healthy enough to keep it going for quite a while. I've never heard of a vehicle that wouldn't run without a functional alternator, as long as battery is supplying enough voltage for ignition. Not saying that's not the case here, I've just never heard of it.

I'd be redoing grounds, looking for wiring issues, bad pcm connector. Looking forward to hearing what the cause is.
 
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Like GL 1500 says, but also check fuel pump and filter. Is there fuel pressure at the engine? If that checks out ok, start looking at the entire ignition system, including the key switch on column, all fuses and relays, then the connectors at the intake and the PCM.
 
Stepside_fever95

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I took it by autozone to see if the warranty on the battery was still good and to check the battery. The battery checked fine and the alternator was charging it like it should when it is running. Im thinking it may be the grounds possibly. All of the fuses looked fine and it is running fine now that its been ran and warmed up. Issue only happens some mornings.
 
Stepside_fever95

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[quote uid=14809 name="OutlawDrifter" post=900666]when does it read 14v?[/QUOTE]<br />When it is running. It decided to crank after jumping it and is doing fine now. Went by autozone to have the battery checked and it was good, and the alternator was charging it like it should. Where are the main grounds at? I know theres one on the frame but arent there several?
 
SAATR

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Also check the power wire running to the power distribution center on the driver's side of the engine compartment. You may have a bad connection there causing you to lose power when all the loads come on after the key switch is back in the run position. It's also possible that the ignition electrical switch could be faulty and losing contact after you release it from the start position. All ignition hot power sources are dependent on that switch working properly. One way to test would be to turn the headlights on and start the truck. If the headlights stay on after everything else goes dead, then it is in your switched power circuit and could be caused by the ignition switch. If the headlights go out, I would look at the power supply to the power distribution center.

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Stepside_fever95

Stepside_fever95

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SAATR said:
Also check the power wire running to the power distribution center on the driver's side of the engine compartment. You may have a bad connection there causing you to lose power when all the loads come on after the key switch is back in the run position. It's also possible that the ignition electrical switch could be faulty and losing contact after you release it from the start position. All ignition hot power sources are dependent on that switch working properly. One way to test would be to turn the headlights on and start the truck. If the headlights stay on after everything else goes dead, then it is in your switched power circuit and could be caused by the ignition switch. If the headlights go out, I would look at the power supply to the power distribution center.

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Click to expand...
The headlights do go out when it cuts out. That wire has been replaced within the past 3 years, need to check to make sure its getting good connection.
 
Stepside_fever95

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It did the same thing to me last night again after several weeks, and jumping it off was the trick. Ive been lazy and havent checked the grounds or the wire from the pcm to the battery yet. Ill probably get to that monday.
On another note, one thing ive noticed is that my 4-hi doesnt work now. Bad relay maybe? Fuse is fine.
 
superdave

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SAATR said:
Also check the power wire running to the power distribution center on the driver's side of the engine compartment.
Click to expand...

I was having an electrical gremlin, and that connection had the slightest amount of corrosion at the connection on the power block. Cleaned it, and no more problem. Computer controlled vehicles are much more sensitive to voltage than older cars. You used to just need a connection. Now, you need a good connection.

My truck would just cut off going down the road (losing all electrical power) and then would cut right back on. Fun on the interstate running 70MPH.
 
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