I just got a 2000 blazer the other day. with that same motor. it ran fine the day I got it. but when I let it sit for 2 or 3 days the motor will just crank over. so at first I thought it was the the distributor cap cleaned it, motor fired right up.. 3 days later same thing just cranks over. so I thought maybe the fuel pump, nope its running, maby the filter??? then I thought well it cant be the filter cause when it runs, its a champ.. shut it off starts right back up. well I looked from front to back. they (previous owners )replaced the fuel pump, filter, cut off the cat(dumb choice there) new egr valve,map,maf, dist cap,plugs which all will give the same systoms of what im going thru. but they forgot to check one thing. today the blazer has been sitting for 3 days. I went out took off the throttle body
air thing and stuck my nose down there and it smelled like a gas can. (RAW FUEL) so I tried to start the blazer and as what I was expecting the motor just cranked over.. so I turned the key on over and over listening to the pump. did this for like 5 min. the truck fired right up. so now im down to two suspects. THE SPIDER IN SOME WAY. OR THE FUEL PRESSURE REGULATOR is not doing its job... when the motor has uncycled gas. (raw) the motor/comp does not know its there so its tryin to compensate(spuddering/hesitate) until that extra gas is burned off then it will run fine, until you notice that your not getttin good fuel mileage..10$ every other day...... so this weekend im going to take off the pleneum and see whats going on. with the spider/ fuel pressure regulator...hopefully that's it only the fpr. I will post back with my findings this weekend....

 

Sounds like it's time to diagnose the problem rather than replace parts 1998 through 2005 S&T vehicles have a vacant terminal in the underhood fuse panel, right next to the fuel pump relay. It is referred to as the "pump prime" terminal. The circuit goes directly to the fuel pump. Connect a fuel pressure tester to the service port near the distributor. Connect one end of a fused jumper wire to the pump prime terminal. Connect the other end to battery positive. When the fuel pressure stabilizes on the tester, write down the pressure. Disconnect the jumper wire. Wait 10 minutes and write down the fuel pressure. Post both of the readings.

 

the thing is I did not replace any of these parts its was already done before I got it. I just went down the line and stopped where they didn't look next.. I just found a spider/fpr for $50 so im picking them up this weekend. I don't have a 10 min leakdown its more like a 2 or 3 day leak down..it keeps pressure for 2 days then nothing....

 

went out today and took off the plenum and the very last bolts I took out were the fuel in and return line. it was finger tight. took the plenum out turned the key on and bam it was leaking from the fuel line in. took it out and looked at it. someone b4 me that worked on the blazer only put 1 out of 6 O-rings on the fuel lines. so I put new o rings in sealed it up turned the key and no leaks. put it all back together and the blazer runs like its new. NO SPUDDERING/SPITING.. BUT I FULLY WONT know about the total leakdown for another day or two. will repost sunday...

 

There is a certain order that the O rings & steel washers must be installed: The black O rings go in first, then the steel washers, then the yellow O rings, then the black seal retainers. Oil the two lines with clean motor oil and gently push them in.

EDIT: There are only 4 O rings: two black, two yellow, not 6. The image you posted shows how they are to be installed.

 

when I took off the fuel line there was no o rings just 1 yellow and a metal piece. so I got some new o rings put them in and there Is no leaks now from what I can tell. It shifts when its suppose to does not run at 2k at 60mph 1 1/2k now don't smell any richness to it. so im hoping I got it fixed........ plenum was easy to remove and replace. THANKS TO BLAZER.FOURM.COM and a lil bit of youtube... from Bellville are ya. I was raised there in ypislanti. lived there for a while.. now im stuck in ohio.....

 

The O rings are not just ordinary O rings. If you don't use the right stuff, they will leak again. This kit has the correct O rings, steel washers and seal retainers. Most auto parts stores will have it, or can order it for you.
Dorman Products - Search Results

 

I don't know what to think. this blazer is unhappily named Christine it now has a security light coming on when I jump in and turn then key it will not start just cranks. starts after about 10 min with the key on, and the light stays on. but when I put the key in let it do its 6 beeps wait a sec it will start(light goes off, stays off) but when you put in drive it wants to spit and spudder for about 15 miles wont stay under 2k at 55 mps until I turn the key off a few times(store,bank,gas station.. then it will run fine all day until it sits again.. im still thinking its the injector cause inside the plenum was clean. does a fowled injector do the same thing. or does the dripping gas fill the cylenders and thats where im getting the spuddering from? until the unregulated gas is burned off? have not had any problems with the o rings..

 

Security light coming on is a Passlock problem, and may be causing some of the other issues. You'll need to have it checked with a scan tool capable of accessing the Passlock system.

 

will the fuel injectors leak any when the key is off.. I took the plenum off and seen gas droplets on the end of the injectors. its not a lot of drips but it seems like its not sealed.. will the fuel pump run if the passlock is not working cause I can hear the pump kick on and off