I had a secondary air injection check valve failed while on a trip, it allowed the exhaust into the system, which burnt through the rubber elbow near the top of the motor. In turn it melted the portion of the wiring harness that crosses its path, causing a stall. Since then, I have replaced the fuel pump, filter, fuel line, secondary air injection system, MPFI (fuel injection) system & crank position sensor. We have repaired the wiring harness as well. It still won't start, if you pour gas in the throttle body it starts & runs, but will not start without. I have fuel to the injectors & it has 60psi of pressure. Is there something I may have missed? Any ideas? I am at my wits end here. Thanks, in advance.

 

For reference it is 2001 LT 4door 4WD 4.3L Automatic

 

Did you do a leak down test? Pressure needs to be 55 psi for 10 minutes after the pump shuts off.

 

if your talking about the little hose comes off around egr valve I had similar problem my wiring burnt up above it but I didn't know replaced fuel pump filtetthe hose that burnt out tps sensor various emission sensors &one wiring harness that was the wrong one parts to the sum of about $700.00 ended up replasing each individual wire cut splice & solder every wire & shrink wrap new wires .total of 80 wires 160 solders all together wiring done & repla30 replaced computer that all said turn over engine starts runs for 20 seconds then dies new distributor cap& rotor put starter fluid in runs 30 seconds and dies take off exaust to see if it runs it didn't kept getting bad mass air flow sensor it was replaced but kept getting the same code im at my wits end by now almost out of money laid off the place I work at let me borrow one of there trucks for a wile but iknew that would come to an end soon so I was to the point that I was going to load it on a trailor and drop it in my drive way didn't know what else to do when me & my boss were looking on the internet and found a check off list about the only thing I didn't replace was the ( map sensor )it runs about 54 for a year one I recommend getting the lifetime one for like around 65 dollars or less !!! with mapsensor pluged in fired right upruns better than it did beforewith all the parts I didn't need but its back on the road again with 200196 miles and counting I believe this is the fix your looking for please let me know if I was rite my blazer is 2001 3.4ltr2 door please let me know if it works e mail me @ gregorian681@gmail.com thanks hop I helped you & others fix their trucks

 

yes, pressure holds at 55-56lbs.

 

all wiring has been reworked, still won't start without dumping gas in the throttle body most of the time, it has started twice without & ran for about 30-60 seconds before stalling. Ran the scan tool cam up with P1336 Crankshaft position sensor, which i replaced, said it can't learn or won't learn the variations...to do that it must be running. I really don't know where to go from here honestly.

 

Thank you both for your input.