Help with 99 Suburban running issue
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Help with 99 Suburban running issue Have a friend with a 99 Suburban with the 5.7L Vortec with about 120k miles on the thing. He is having a problem with the truck running for about 10 minutes to the point it warms up and it will die off. After it dies and we try to start it back up it just cranks over and over. We sprayed some starting fluid into it and could get it to fire up for a quick second but it would die again.
Hooked up my scanner to it and watched it and seems like when it was dieing the Narrowband O2's had a long delay before any information really changed, up to 4 seconds sitting at 80. Went through this cycle about three times and than it died looking back at the scan. MAF was getting a signal and the truck isn't throwing any codes. Fuel pump is new and can turn it on with HPT and can hear it pump up and the schraeder valve spews out gas, doesn't drizzle out so pretty sure it isn't a problem with the fuel getting to the engine. There is also spark so that eliminates any speculation on any sort of crank sensor or anything ignition related being bad. Only thing I can think of is that something for the injectors is overheating. I was wondering if the O2 sensors could be bad but I would think if they were bad the truck would just run like crap and not just die.
Anyone have any suggestions of other places to look. I am pretty sure it is something Injector related but not sure what it could be. Like I said, fuel is getting to the manifold but for whatever reason it isn't getting to the cylinders. Pretty sure they are not plugged, if they were I would expect it not to fire back up after it sits for a couple hours. Anyone else experienced something like this?
Hooked up my scanner to it and watched it and seems like when it was dieing the Narrowband O2's had a long delay before any information really changed, up to 4 seconds sitting at 80. Went through this cycle about three times and than it died looking back at the scan. MAF was getting a signal and the truck isn't throwing any codes. Fuel pump is new and can turn it on with HPT and can hear it pump up and the schraeder valve spews out gas, doesn't drizzle out so pretty sure it isn't a problem with the fuel getting to the engine. There is also spark so that eliminates any speculation on any sort of crank sensor or anything ignition related being bad. Only thing I can think of is that something for the injectors is overheating. I was wondering if the O2 sensors could be bad but I would think if they were bad the truck would just run like crap and not just die.
Anyone have any suggestions of other places to look. I am pretty sure it is something Injector related but not sure what it could be. Like I said, fuel is getting to the manifold but for whatever reason it isn't getting to the cylinders. Pretty sure they are not plugged, if they were I would expect it not to fire back up after it sits for a couple hours. Anyone else experienced something like this?
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I was trying to remember if the car has a safe running mode if they fail but I couldn't remember for sure. I know that the MAF can run the car still half assed if it is unplugged or dies... just a dramatic drop in performance.
Think both of them being bad could cause it? Was thinking it was Bank 1 because it was the one that seemed to have the longer delays in the scans.
Think both of them being bad could cause it? Was thinking it was Bank 1 because it was the one that seemed to have the longer delays in the scans.
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FormerVendor
Joined: May 2004
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From: Portland Oregon
If you got spark and fuel then it has to be something with the injectors. But you MUST verify that the fuel pressure is OK. The main reason is because you have a 5.7 Vortec which uses a poppet style injector inside the intake plenum. This style injector needs at least 55 PSI of rail pressure and no less than 50 at idle to run properly. If it doesn't have 55 to 60 PSI it won't start properly. If you verify that you have the correct pressure and that spark is getting to every spark plug then its the injector pod.
Also the other main igition problem with the Vortec engines of that vintage is the distributor cap, they will burn through inside from the center electrode and short between the different cylinder contacts. This is a very common problem with these, also inspect the coil wire. When you replace the cap, don't go CHEAP here get the best cap you can such as a OE AC Delco piece, Blue Streak, NAPA Gold Series, most parts house carry a el-cheapo line of ignition parts, don't go there.
Also the other main igition problem with the Vortec engines of that vintage is the distributor cap, they will burn through inside from the center electrode and short between the different cylinder contacts. This is a very common problem with these, also inspect the coil wire. When you replace the cap, don't go CHEAP here get the best cap you can such as a OE AC Delco piece, Blue Streak, NAPA Gold Series, most parts house carry a el-cheapo line of ignition parts, don't go there.
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Hey, Had a suburban roll through here years ago with the EXACT symptoms you described. Ran fine for a little while then would kinda stumble and die. Then it would not restart till cooled down.....
Wire from coil to distributor was bad! It would get so hot that it started melting.
Wire from coil to distributor was bad! It would get so hot that it started melting.
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