2002 Suburban - Motor Swap - Won't Start

[mrharris32]

I've just recently replaced the motor in an 02 burb. The old motor had 270k miles and had some fairly severe bearing damage. I picked up a new motor (complete) with 71k miles, I am 100% positive the motor ran fine before I purchased it from LKQ (huge salvage centers nationwide).

After about 35 hours of labor I've got the old motor out, the new in and everything connected...every sensor, every wire, fuel, etc. I've been wrenching for over 12 years so this isn't my first rodeo. After installing the last of the parts (fan shroud, heater core hoses, connecting the battery) I hopped in and turned the key. Turns over fine, oil pressure jumped right up, motor studdered a few times. I hopped out and purged the air from the fuel system (using the purge valve on the incoming fuel line top of the intake), standard protocol on any late model 5.3 swap. Turn the key again assuming she'll fire right up, turns over and hits just a bit but will not start.

After several hours of troubleshooting I'm still stuck. I plugged in the scanner and received NO codes whatsoever. The only variable in the electrical system was the camshaft position sensor, the pigtail was destroyed when the old motor was removed...I wired in a new pigtail using the wiring diagram found in a Chilton's for 2000-2006 Chevy 1500/Suburban/Tahoe. I pulled the connector from the back of the intake (not easy when everything is installed!!) and cranked the motor, immediately got a code the the CPS was not functional. Basically I was trying to rule out whether or not the wiring could be off....it appears to be fine however.

With that said the only other issue with the motor is one bolt missing on the driver side exhaust manifold, you can hear it squeaking out a bit but nothing serious and certainly nothing that should cause it to not start? From my experience I am leaning strongly towards the engine being seriously out of time...it's shooting fuel/firing spark at the wrong time. There is no way to my knowledge to adjust this...

I'm at a loss, 12 years and tons of swaps, never had this problem. Could there still be air in the injector rails? Did I miss a crucial step required before turning over a new motor in a 02 Burb? I'm looking for any input and will give as much info as needed, I need to get this vehicle going ASAP.

Thank you in advance for any assistance!

[MT-2500]

Originally Posted by mrharris32

I've just recently replaced the motor in an 02 burb. The old motor had 270k miles and had some fairly severe bearing damage. I picked up a new motor (complete) with 71k miles, I am 100% positive the motor ran fine before I purchased it from LKQ (huge salvage centers nationwide).

After about 35 hours of labor I've got the old motor out, the new in and everything connected...every sensor, every wire, fuel, etc. I've been wrenching for over 12 years so this isn't my first rodeo. After installing the last of the parts (fan shroud, heater core hoses, connecting the battery) I hopped in and turned the key. Turns over fine, oil pressure jumped right up, motor studdered a few times. I hopped out and purged the air from the fuel system (using the purge valve on the incoming fuel line top of the intake), standard protocol on any late model 5.3 swap. Turn the key again assuming she'll fire right up, turns over and hits just a bit but will not start.

After several hours of troubleshooting I'm still stuck. I plugged in the scanner and received NO codes whatsoever. The only variable in the electrical system was the camshaft position sensor, the pigtail was destroyed when the old motor was removed...I wired in a new pigtail using the wiring diagram found in a Chilton's for 2000-2006 Chevy 1500/Suburban/Tahoe. I pulled the connector from the back of the intake (not easy when everything is installed!!) and cranked the motor, immediately got a code the the CPS was not functional. Basically I was trying to rule out whether or not the wiring could be off....it appears to be fine however.

With that said the only other issue with the motor is one bolt missing on the driver side exhaust manifold, you can hear it squeaking out a bit but nothing serious and certainly nothing that should cause it to not start? From my experience I am leaning strongly towards the engine being seriously out of time...it's shooting fuel/firing spark at the wrong time. There is no way to my knowledge to adjust this...

I'm at a loss, 12 years and tons of swaps, never had this problem. Could there still be air in the injector rails? Did I miss a crucial step required before turning over a new motor in a 02 Burb? I'm looking for any input and will give as much info as needed, I need to get this vehicle going ASAP.

Thank you in advance for any assistance!

What engine?
What is the fuel pressure?

[mrharris32]

It's the 5.3L Vortec. I have not tested the fuel pressure....the old motor (with bad rod bearings) was getting fuel fine, so the pump is working fine. Is there a way to bleed pressure (air) directly from the rail or is the only option to do it at the nipple on the incoming fuel line on top of the intake?

[MT-2500]

Originally Posted by mrharris32

It's the 5.3L Vortec. I have not tested the fuel pressure....the old motor (with bad rod bearings) was getting fuel fine, so the pump is working fine. Is there a way to bleed pressure (air) directly from the rail or is the only option to do it at the nipple on the incoming fuel line on top of the intake?

They bleed there self.
But you need to put a fuel pressure tester on it and pot back pressure reading.
Specs are 55-62 lbs.
You will need 60 lbs for a cold start.
Can you hear the fuel pump on 2 second prime key on or engine cranking?
If not check fuse and relay.

[777stickman]

If the fuel pressures check out ok per MT, you may want to do some research on setting the dizzy @ #1 TDC compression stroke. This is very critical and then can be adjusted for cam retard/cam offset (base timing) once the motor is running.

[j cAT]

this engine the 5.3L has a cam position sensor and the crank position sensor.

the crank sensor is under the starter . using a fuel pressure guage make sure you have the correct fuel pressure.

the other item would be the ECT . if this is out of range it will cause poor starts.

disconnect the maf see if it starts.

then theres the secuity system messed up where the engine will almost run then die quickly.