I am in need of some serious help. I have a '98 Blazer 2WD 4.3L V6 Automatic. The problem I keep having is that it seems to like to stall out everytime I want to go somewhere semi-far. If it is driven for an extended period of time (about 30-35 mins) the Blazer will stall. It only stalls out while sitting at a stop light or just taking off from a stop light (light throttle applications). After it stalls I need to wait at least 15-20 seconds before it will start again (it will crank but will not start before then). When it happens, it's typically when I take off from the light. Then, it will drive fine for a few minutes and it will happen again (again while sitting at a light or just taking off from a stop). I have no idea where to begin at guessing. It does not throw any error codes. The check engine light is always on for something else. The light is for a P0440. No idea about that one either. The radio and everything is still on it just shuts the motor off. Also, I don't know if this means anything, but my oil pressure gauge twitches. When driving it sits at about 60-80 but at idle it drops down to about 30-50 and twitches back and forth. Don't know if that helps. I really need to figure out what this is and get it fixed. Any suggestions?

 

Do some reserch on fuel delivery and ignition switch. Good stuff in the DIY.

 

It could be an air sensor. How long has it been since you checked the transmission fluid? Take it to auto zone and get a free diagnostic ran on it. That should pin point any sensors and just so you know, Blazers are notorious for burning through transmission fluid which can lead to big problems. Hope that helps ya.

 

All my fluids are good. I will take it to Advance and AutoZone and see what they say. Hopefully something worthwhile.

 

Tell us about the truck's idle when it's warm. should be at a steady 650 or thereabouts.
And how does the tach act when you pull up to the stop?

Also your oil pressure should never go more than a little over 60 lbs. If it goes near 80, you have a problem in your oil pump internal bypass valve. Or the sender is bad. The twitching raises questions, a little is normal, movement related to engine rpm is normal.
It would not cause the truck to stall, by itslef but the same thing causing it to twitch downward in reading could. Bad wiring grounds at rear of engine.

Note: While it COULD be a bad air sensor, those usually have other symptoms as well, not just falling on their faces.. or stalling when accelerating from stop. Best case pointing to that would be runs fine and smooth when cold, hesitate on accel at any speed when warm. That points to a dirty MAF.
If you have THOSE symptoms as well..meaning hesitate on accel from any speed, check by warming up, the n disconnect the MAF connector with engine off then a drive test. if it drives better clean your MAF. Good idea to clean it anyway.. whether or not.

The above is not conclusive. It really sounds more like a primary ignition problem if all else is good.

 

I dont know about the idle. It idles just fine and runs smoothly cold or warm. It just stalls out when taking off after it has been ran for a while. I do not have a tachometer so I couldn't tell you what it shows. I will try to disconnect the MAF in probably tommorow before work. Would that make it stall? Like I said there is no hesitation, the Blazer gets up and boogies everytime.

 

Defintely clean your maf with maf sensor spray. Then due a tune up with delco plugs,cap and rotor. Clear your code and you should be good to go. Use only delco or you will get codes, these trucks run best with oem.

 

A few months ago, I did clean the MAF with MAF cleaner. I was getting a code for it and I cleaned it out. Also, the plugs and wires are brand new. I just put the motor in about 7000 miles ago (new plugs, wires, cap, rotor, gaskets, etc.).

 

I have to point out that a dirty MAF affects performance before it ever sets a code.. it has to be grossly off to set it. Meantime fuel trim will be to lean side.
And just spraying cleaner on it one or two passes rarely gets it all the way clean, esp if it was bad enough to set code.
Now on this next occasion that the truck stalls and wont start get out and disconnect the MAF harness and try it.

MAF problems manifest in several related ways
Read this
https://blazerforum.com/forum/2nd-ge...takeoff-69188/

 

I have since fixed this problem on my Blazer. It is the fuel pump. I guess it was running too long and "overheated". I replaced the pump and voila, it was fixed. In case anybody else has been having this issue, this is the answer!