Just got the Maggie done and can not keep it running. Pulled the 4.8 and the 4L60e. Put in a 5.3 and 4L80e. New sensors Headers a Nelson tune. Sound good what little it has run. Will run for just a minuet then shut off. Has the booster pump but dose have the stock pump in the tank. What have I done wrong?

 

What's the fuel pressure? Sure you don't have one helluva vacuum leak somewhere?

 

Do not hear any leak. Will check the fuel pressure tomorrow. That is what I am thinking. The vacuum may be a little harder to find.

 

if it'll run for just a minute, be sure the maf is working, the engine could be going lean.
be sure the iat is connected, could be running really fat and dying.
if the engine revs up and then comes down slowly upon start up, check for vac leaks. Use a smoke machine to detect vac leaks.
if the o2 isn't reading correctly, the pcm may be trying to add fuel and can't add anymore, so it's starving for fuel.
check fuel pressure since you did a pump.

if you have access to a scan tool, send some data over, even a predator will work just to get an idea on what's going on.

if you keep it running, hopefully a cel will come on, that'll help determine.

good luck and let me know,
allen

 

No black smoke so I do not think it is fat. Hard to start but will after cracking on it a little. When it dies not a it dies slowly not just a fast shut down. No popping just slowly dies. A friend has a scanner and is going to bring it tomorrow and help me a little.

 

try this, turn the key to the ON position several times before attempting to start, if it starts right up, check the fuel pressure. Sounds like it might be low on fp.

 

Thanks I was thinking about that. I never did hear the booster pump come on that may be the trouble. Get some help tomorrow and will be able to do more.

 

What computer did you use? How long did it run?

 

Got it going. Forgot to cut the Tan and Black wires on the MAF and put them on the new sensor. But it is Idling way to high. At 3000rpm's. Did not get to put the scanner on it but will tomorrow.

 

Might check for a vacuum leak.