I'll apologize in advance for the length of this post and will try to be brief, but ……….

2000, 4DR, 4WD, 4.3 L, Automatic has me stumped. Back in October 2017 it left me stranded on the side of the road with a no start condition. Repairs prior to this episode include various interior trim fixes, Crank Position Sensor replaced and relearn accomplished, replaced all plugs / wires / cap / rotor, replaced trans valve body and all solenoids / harness / filter, replaced TPS and MAF. Vehicle had been running well with no issue prior to this event. Dragged it home and started the diagnostics. Fuel pressure was good at 60 with key on and slowly leaked down to 30 with key off. Can't remember the exact code but SES gave a code for ICM which I replaced with a Standard Parts #LX381T and the distributor pick-up which I replaced with Standard Parts #LX756T, I cleared the codes but those parts didn't fix the no start. At that point I got disgusted and walked away.

I now have a need to get it fixed and got back on it. Started from scratch with fuel pressure and found none. turns out the pump was bad. Replaced the pump with a Delphi and installed a new filter as well. With high hopes I tried to start it but got butt hurt. No love. Rechecked fuel pressure and got a solid 62 with the relay bypassed or with the relay in and key on. With the relay bypassed forcing the pump to run I can hear a hissing sound from the top of the engine near the distro. I assume its coming from the fuel pressure regulator. Does that make sense?

Here is exactly what it does: With the key in the start position for several seconds the engine turns but doesn't fire. As soon as I return the key to the run position the engine fires and runs but sounds like only one cylinder is firing and then dies after a 30 secs or so. it will do this repeatedly.

I'm stumped ……………… Help …………...

 

sounds like you have a leak under the plenum - ing line - regulator - ect - I would pull it off and there should be a clean uncarboned cleanish spot where the leak is.

 

remembered that I had originally posted about this back in October 2017, here's the link.
https://blazerforum.com/forum/2nd-ge...el-pump-95406/

 

I was just going off the hiss sound and the fact it's not holding fuel pressure. the running kinnda on one cyl could be because of fuel flood due to a leak ....

 

Ya, you need to deal with the fuel pressure leak down.

Do you have 1" of strong blue spark at the plugs?

George

 

I could understand a hiss from a leaky plenum if the truck was running and sucking air. Not the case here. Yes, I have strong spark ( at least at cyl #3) lol.
Tried to track down the hiss and seems to be coming from the fuel pressure regulator. Removed the power plug from the Spider assy and no change. Beginning to believe I have a faulty regulator or spider assembly. Either way, unless someone tells me otherwise and leads me to another solution, it seems the plenum / manifold has to come off to eliminate any doubt. Of course if I'm breaking it open anyway wouldn't it be a good idea to replace the spider while I'm in there. Opinion and best parts options welcomed. THX

 

Ya I was implying a fuel leak under the plenum and not the plenum it's self. Depending on what you find for a leak and condition and looks of spider on if I would replace it. Plenum really isn't that hard too pull and spiders are a little pricey to replace on a while I'm in there - However I usually don't but have been known to do such things ....

 

Soooo ……. here is the latest.
I had a friend come over (new eyes and fresh mind you know) and we started from scratch. Good spark - Yep. Good Plugs - Yep. Good fuel - Yep. Good compression - Yep.
Bypassed fuel pump relay to identify hissing around injector control unit and reasoned that we were hearing excess fuel being routed back to the tank.
Discussion ensues --- If you have air, fuel, spark and compression then it should run if timing is correct -- check timing.
Well, well, well …. at TDC the rotor is pointing at #2 on the cap. WTH? How is that possible?
Yes, I replaced the distributor last week but marked it before removal and it went back exactly as removed.
Repositioned distro and it fired right up and runs pretty well with slight miss at idle which is probably a slightly fouled plug . Drives just fine with good acceleration.
Yeah ………….. back to a useful vehicle. Hopefully there won't be any further issues for a while.

Thx for the suggestions and help.

 

Thanks for the report back. These follow ups are super helpful.

And congrats on getting it running.

 

Glad she's up and running - The hiss and regulator returning fuel is A possibility but depending on how long it takes with key off to bleed pressure to 30 and below - the regulator may be getting weak - KO = 50psi+ for at least 5 min. even better if it holds for 10 min ....