Ive been working on a friends 01 blazer for about a week now, it is a W engine code to start.

When I first started working on the vehicle it wouldnt start unless you put a little fuel down the throttle body and it would run until the fuel burned off.

I checked the fuel pressure and noticed it was only running roughly 35psi cranking and when the pump stopped running the pressure would drop down to <10psi within 5 minutes. After seeing that we replaced the fuel pump and filter. Now the pressure shoots right up over 60 while cranking but still bleeds back down just as fast so we replaced the pressure regulator under the intake as well as all the gaskets but that didnt fix the bleeding back issue though nothing is leaking visibly from anything under the intake or in the lines.

Unfortunately the vehicle still wouldnt start so i hooked up the scanner to it and it was throwing a camshaft sensor code, replaced the sensor and the code went away. Still would not start even with fuel being put in the throttle body anymore.

Replaced the spark plugs and it has spark at all plugs as well as power and ground at all of the injector pins in the connector.

Went through the diagnostic procedure in the sticky at the top of this forum as well as scoured for hours online trying to find someone who has posted a similar issue with all the same symptoms in other forums as well as this one.

I am starting to get a very bad feeling its the spider injector box but hoping that it is not that and something we are missing since alot of money has been put into the blazer in the last few months and its starting to seem like an endless money pit.

Any ideas would be greatly appreciated

 

Im have the same problem with my jimmy I was told it was the spider injectors by a shop but if anyone know please let me now also

 

I to had this same problem and it ended up being the wires that go to the spider the red and the blue ones . Its only about a foot long and connects behind the power steering pump and goes to the spider injector .

 

To the OP, did you move the distributor when you replaced the CMP sensor?

The next step I would take is to determine if the fuel pump holds pressure if you were to disconnect the fuel filter and test there. If it doesn't, then you know the leak is in the tank. If it does, then the FPR is at fault and the upper intake plenum needs to be pulled.

The SCFI setup that came on the 96+ trucks is much different than the CPI setup that came on the 95- trucks. There are 12 wires total to the injection spider on the SCFI/MFI engines.

 

Sorry it took so long for me to get back on here

When we did the cam sensor we didn't pull the distributor just used a short ratcheting screwdriver with the torx bit and pulled the sensor out through the little groove of the distributor that the rotor would screw down onto so its definitely not installed any different then when it was running with fuel down the TB, there's no correlation fault codes on the scanner coming up either.

Checked power at all injectors and getting power and ground at each one

used an adapter to check fuel pressure before the fuel filter and held pressure at the tank and the rear half of the fuel lines. don't think theres a leak coming from the filter either because in theory you would think it would be somewhat visible at the other side of the filter at the rate the pressure drops (60-0 in roughly 3 min give or take 30 seconds). no leak from the regulator visibly or with some simple green sprayed over the back of it to see if its air, same with the filter.

He Broke the bank and ordered from carquest a new injector unit yesterday which converts the injectors to MPFI out of need to get this thing to run since rental cars aren't cheap, hopefully some good news will come out of it or its a $300 waste, find out on monday

 

Swapped out the injector unit today and it fired right up, fuel pressure still bleeds back when the pump is not running but much less than before.

Strongly recommend the MPFI replacement over the original spyder, just seems to run a bit smoother IMO.

Thanks for everyone's input.