I have a 2000 Blazer that sat for 2 years (until about a month ago). Reason is sat was that I had to do the lower intake gasket due to a slow coolant leak. I got that done, and also put in the new spider while I was at it, along with new AC Delco plugs.

It had a full tank of gas when I parked it.

Anyway, my issue is that when I first start it, pushing the gas pedal won't let me get past 1000 rpm. It idles smooth, just won't build rpms. If I start driving, it will slowly increase in rpm, and after about 30 seconds or so, everything is fine. I went for a 30 minute test drive and no issue at all. Park if for any length of time (well, 5+ minutes lets say), and I get the same thing again.

I should note that when I first jump started the Blazer before doing any work to it, it behaved exactly the same. I was impressed that it started right up within a few seconds of cranking, after sitting for 26 months.

 

How did it run before you parked it 26 months ago? And what fuel injection system does it have? I'm not sure if they all have the same F.I. system in that year...

Meanwhile, I'd go ahead and change that fuel out just in case (I'm sure that you changed the engine oil when you did the lower int. man). Ethanol blended fuels do not do well over time.

Besides that, I'd make sure that the coolant temp sensor towards the front of the int. man (if equipped) is in proper working order (clean connections, good wiring and connector, etc). Also make sure that all the under hood electrical grounds and wires are good, clean, and tight (there should be one main ground at the back of the passenger side cylinder head along with one of more on the int. man. Another thing to check would be the Throttle Position Sensor (this might be the first thing to look at).

 

So the Blazer belongs to my mother in law who moved in with is about 3 years ago. I replaced the water pump 27 months ago, and then that didn't fix the coolant leak, I parked it and have been meaning to get to doing the intake gasket, but other stuff kept getting in the way. She moved in with us about the same time, and was able to use other family vehicles when she needed to go somewhere, so I kept putting it off.

At any rate, I never really drove it myself, other than from the house down to the shop to work on the water pump and then to the place it sat for 26 months. I honestly don't recall if it was doing it before.

Here's the injection system that was on it originally:



And this is what I replaced it with:



While I had the intake out, I did spent some time cleaning up everything, including the wiring and connectors, but I'll double check everything, especially the throttle position sensor. I did get a Service Engine Soon light on my 30 minute drive. This one:



So I pulled the MAF and gave it a thorough cleaning with some MAF cleaner spray. No codes since, but then I haven't taken any long trips since.

One thing I am noticing is that all the gauges in the cluster are "jumpy", both with the engine running and not. So maybe there is some electrical gremlin somewhere I need to find. I'll be sure to double check the ground on the passenger side cylinder head and intake manifold. I remember doing the cylinder head one, but not the intake manifold one.

 

Glad you mentioned the SES code (I forgot to ask that very important question). The MAF or Volume Air Flow sensor could, of course, still cause the drive-ability problem. But I'd go after the above mentioned grounds first.

As for the front int. man temp sensor, I'd carefully remove it, clean the threads (both male and female) apply the proper thread sealant, and tighten it to specs (but first check the connector and wires).

Did you notice the 'jumpy' gauges before you worked on it? Either-way, the first thing to check with this would, again, be the grounds. IIRC, some Blazers and/or full sized truck/suvs have an instrument cluster ground located on the driver's side frame rail just under the D.S. seat area that is known for 'going' bad (not sure about this in regard to your Blazer, but you might want look around under there just to be sure).

Note: Be sure to closely check the P.S. rear cylinder head ground wires for broken, or partially broken, wires. These, and other under hood wires (both ground and non-ground types, are known for failing due to heat and age (this includes the 'main' eng. harness that runs along and/or across the int. man).

 

Thanks for the suggestions, I'll check those after I get home from work today.

I don't recall the gauges acting up before the 26 month hiatus.

 

You need to drain that old gas...I bet it stinks to high heaven. Plus leaving it set for so long everything fuel related has a varnish build up on them...after you change the fuel run some carb/injector (prefer SEA FOAM) to clean everything out. The MAF sensor might have to be replaced...Sounds like you have a lot of work ahead of you...Good Luck.

 

So I went to drain the old fuel today, but I guess there is some sort of anti-siphon where the filler neck enters the tank, because I was not able to get my tubing any further than that. I tried removing the filler neck from the tank end, but it did not want to give, so I ended up removing the breather tube next to it:



And drained the ~15 gallons into some 5 gallon containers I had sitting around:



With the old fuel out, I poured about 3 gallons of fresh gas in the tank, and boy what a difference it made! Starts right up now and no hesitation rewing.

Drove it around for a little bit around the house and it seemed to keep getting better. Guess I'll run to the auto parts store and grab some SEA FOAM, need to stop by the ABC store anyway for the weekend.

Good call on draining that old gas!

 

after the seafoam or even fuel system cleaner i would change the fuel filter down the road. Good luck, sounds like your on the right track

 

Man, I took the Blazer down to the lower part of my property (I got a little over 20 acres to play on), and man, I'm really digging this Blazer! Never really drove one before (recall this one belonged to my mother in law and she gave it to me). I was going to sell it, but now I'm not sure. Hmm.

Other vehicles I currently own:

2002 4Runner Limited - This has gotten me out of some crazy tough spots, especially in snow. Technically belongs to the wife
2002 Silverado Duramax Crew Cab Long Bed LT - This is the big boy. Got a Warn M15000 up front and running 285 Mud Terrains. I have yet to get this stuck to the point I could not pull myself out.
2002 BMW X5 4.6is - This is a pretty rare specimen. Currently in the process of doing a complete rebuilt, you can see it in the above pic. Engine and trans are currently out.
1998 Subaru Legacy GT - This guy is amazing all round. Only has 120k on it. I don't think it will ever quit on me

Sorry, did go to the ABC store and I think I am already starting to ramble...

 

I need a garage like that!!