99 Suburban will not start!!!

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cree1988

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k so here's the deal...
99 Chevy Suburban
350 5.7 vortec
k1500 4x4
about 210,000km (I know....)
a few months back it started running a little rough, not accelerating as it should. It would only allow me to get to about 80km/h
that gradually started to decrease to about 40km/h up until it would not start at all. When I started noticing these symptoms it also started to get harder and harder to start until I had to prime it everytime I needed to start it...
now it wont start at all. when I prime it it will fire up for just a couple seconds then die out. I already changed fuel pump and fuel filter, tested fuel pressure got a 55-58psi when turning the key. changed timing chain (as per requested by my local shop) and changed crank sensor.
this is where I'm stuck. not too sure what my next move is.
when I turn the key the motor cranks but thats it. It seems as though gas is not getting into the combustion.
not sure how to troubleshoot. if anybody has any ideas, tips or hints please help me out... its been sitting in my driveway for about 2 months as my budget limits me to there....
 
also the oil pressure was pretty low, can't remember exactly what it was at because its been so long since I've last started it, but it was pretty low.
 
ruled out the security system...
I ordered the original factory key fob that dissables it when you hit lock then unlock...
 
did you have a check engine light when it was running? do you have a security light on when trying to start? have you tried changing the ignition switch? do you have access to a tech scannner
 
no check engine light...
security light comes on for a couple seconds then goes out...
have not tried ignition switch... (should I if it starts when primed???)
no tech scanner....
 
its as though the fuel is not making it to the cumbustion chamber, but there is good pressure in the fuel test valve...
 
check the injectors then, maybe they are clogged
 
Not sure what I did but after constant priming through intake I got it to hold a rough idle. Although once the gas is pressed it will stall. Prime it again and it will stay at idle. I get the rpm to rev up by very slowly pressing on gas. Rpm will not go more than 3000.
 
Does that thing have a throttle body? If so, perhaps you should remove it and give it a thorough cleaning. Maybe the AIS is sticking on it? I could also be something as simple as a clogged catalytic converter too. Check that.
 
I will check that later today.
P.S thanks a lot guys for even taking the time to read my post.
Very much appreciative!
 
Did a thorough throttle body clean today. Was dirty but not as dirty as I would have thought it to be. Removed the AIC motor and cleaned that. Put Seafoam Motor Treatment in the gas tank and in the PCV port on the valve cover. No change at all. I can rev it up but I have to press very slow on the pedal or it stalls.
 
Does that model have a mass air flow sensor? If so, just tap on the pipe it's mounted into and see if that makes a change in the idle. I'm just grasping at straws here, but I've heard that a faulty MAF sensor can really screw with one. Also, have you checked that catalytic converter?
 
Sorry for the long response, I'm a first time daddy and I'm still getting the hang of things.
Did MAF tap thing, no change in idle. Not too sure how to check the catalytic converter.
Here's a link to the video i recorded. I can get the rpms up when I step on the gas slow and light but when I press with force it chokes out.

http://www.youtube.com/watch?v=sXzOwZosL8Y&feature=youtube_gdata_player
 
You check the convertor by disconnecting the exhaust pipe going into it and seeing if your issue is resolved.
 
took me and my buddy awhile but we got it.... disconnected the exhaust from the rear of motor and still no change rather than being quite loud...
I'm tearing my hair out here
 
Hmmmm, maybe the fuel pump is on the way out. Does your fuel line have a schrader valve in it? If so, you can get a fuel pump pressure tester from Autozones loan-a-tool program. It's a $150 deposit plus tax to "rent" it, but you get that money back when you return it. With the engine off, wrap the fuel line with a couple of rags and depress the valve to let the pressure off, then connect the tester. Turn your ignition switch on but DO NOT crank it. Check the gauge and see what pressure you have. Leave the key on for five minutes and check the gauge again. If you see more than a five to seven pound drop in the pressure, then your fuel pump is probably dying and needs replacing. If it holds pressure, then you've eliminated that as a problem. I don't know what pressure your particular pump should hold, but I'm sure someone her could tell you. One other suspect could be a fuel pressure regulator that's going bad too, if your vehicle has one.
 
If this truck has a Vortec in it then it has a web injection system in the intake which I believe has 8 injectors instead of the two like a throttle body, these injectors could be clogged and need to be changed. The throttle body looking ring in the center of the intake is a Plenum for the air intake, and has nothing to do with fuel delivery. I would suggest a full tune up, cap rotor, ignition module, wires, and plugs, as well as pulling the injectors to inspect their condition, they can become corroded over time and may need to be replaced. This can be a real pain but keep in mind that you are looking for a spider it has a header/common rail and eight legs these will more than likely be the problem. If your fuel pressure is what you said it's where it should be for this system. and don't worry about the miles on the truck i've seen them go upwards of 400,000 if well maintained, I have a 72 GMC with over 350,000 on the original engine, still fires up with a slight touch of the key and will lay rubber when it needs to.
 
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