'95 s-10 Blazer 4.3 "W"
Just changed CPI due to running extremely rich, black smoke, and hard starting. I had obvious washing as they call it inside the manifold and changed the nut kit while I was there. For two days it ran great but now I have the last annoying problem that was there previously to changing the CPI. I descibe it as a hard hesitation in the motor when driving. It's like the Eng. just stops almost most, I would consider the hesitation mildly violent, it never stalls however. I do notice also during the times when it acts up when I come to a stop the idle is very high. Since changing the CPI unit last week I have no more smell(richness), no more smoke, and starts easy again.

Read the thread with the Eng. codes and will try Autozone in the morning but one question. How do I know which computer I have the OBDI or II. My test port sits just below the steering column and has what appears to be a six pin connector(there are blank pin positions). I read to jump A and B together to do your own testing but I have 6 pin outs and do not know which is A or B. Can I do this test myself.

Any help would be greatly appreciated. Thanks in advance.

 

A Haynes or Chilton Manual on your Blazer will tell you which pins are where. You can retrieve the trouble codes yourself and it is really easy. Walmart sells a code reader specifically for GM. It sells for around $35.00. It is the best money you'll ever spend on a tool. It makes life so much easier. If you buy a code reader that is made specifically for the make of the vehicle is just plugs in no jumping pins or any of that.

 

a 95 would be obdI. obdII started in 96, although in california it may have started before that. if the plug is reatangular, it is obdI, if it is a trapazoidal shape, it is obdII.

 

Have you tried disconnecting your O2 sensor?
If she runs without the hesitation, then your O2 sensor needs to be replaced.

When was the last time you gave it a tune up?
Plugs, wires, cap, rotor, air filter, fuel filter, PCV vavle, and clean the EGR.

 

Autozone was great and took the time to run my codes had the Idle Air Control hit along with the Throttle Position sensor. Changed the Idle Air and that seems to have cleared me up. Run the vehicle all weekend running good. I did a meter check on the Throttle position and it seems to be working. The service Eng. light went of after putting the Idle Air in but then Sunday morning came back on. I may just change out the Throttle Position anyhow, even though she is running good now. Not sure how much a OBD I scanner cost but that would be great to have. Then again AutoZone was great because they did it for free.

 

Okay now I am confused. Since the light went back on Sunday I went back last night Weds. And asked him to pull this code. It pulled the temp sensor that is in the intake boot, the rubber boot that connects the air filter this time, no throttle position sensor hit. Why or how could it pull a throttle sensor code one time but not the next time, and this time pulls a temp sensor but not the last time. ?????

One more question, the Autozone tech says mine is a OBD II, Just trying to figure out who is right and wrong. The connector is rectangler, not much more I can tell you. Is there a sure fire way to know. Right now my SES light is on but from the last hit most likely(last Sunday), now that the temp sensor is in I would like to know if there is anything else new but do not want to wear out my welcome at Autozone either. One poster said you can buy a code tester from Wal-mart has any else purchased one? Thanks

 

Did you disconnect your battery and reconnect it since replacing the IAC valve?
Give that a shot. When is the last time you replaced your air filter?

I bought a tester from a local autoparts store for like $30 or so. I used it on my old '93 Astro van. It don't fit on my '87 S10-Blazer. Haven't tried it on my '93 or '00 S10-Blazers yet. Maybe tonight if I think of it after work.

 

I have a 95 blazer 2WD 6 cyl vortec with CPI (VIN code designation S). I found that although I have the connector pin for the odbII scanner/computer under my dash in actuality I have an ODBI computer on board. I used the jumper method (paper clip) to pull my codes. It's the two pins on the top row that are right next to each other. What I'm saying is, without looking at it right now to be sure, I think there is one more pin in the top right most slot, but there isn't one in the slot just to the right of that. So, move over to the last two pins that are actually right next to each other on the top row and insert a paper clip or jumper into these two slots. You will turn the iginition on without cranking-look at the service engine light. It will blink out your codes. The first will be a blink-pause-blink blink. Thats a 12. It means it's reading the computer ok. That will repeat three times, as will any other codes that come up after that, then it will all repeat the sequence again, starting with the 12. So after you get the 12, if you get something else write down the number of blinks. Then just look in the manuel for a cross ref. I was getting a blink pause blink pause blink pause blink blink. That was a 32. EGR valve. And then I also got a blink pause blink pause blink pause blink pause blink blink blink blink blink. That was a 45. O2 sensor. I'm chasing the first problem before I replace the sensors, because I believe the sensors are picking up the rich/lean mix because of the EGR. (long winded but insightful when I was given a similar scenario a while back, by I think loloblazer87)

Hope that helps...let me know if you need more explaination and I'll try and clarify

Now I'm chasing a fuel delivery problem...I've read a lot about it on here, and plan to start with the simple stuff like fuel filter replacement. I hear the fuel pump engaging as well as the relay switch clicking. So I'm curious why I'm getting turn over without cranking. By the way, it's my son's car and he let it run low on oil. I read in the Haynes manual where low oil pressure causes the oil pressure switch to act as a emergency fuel cut-off device. I am assuming that was the culprit. But I don't know and can't find a reference to where these switches are to reset them. I did by the way change the oil and make sure it's at capacity. Hoping as any DIY would that it would simply pick up that fact and reset itself. Ha/ha

 

Fuel problem.

The fuel pump will engage when the key is turned to the on position, the start position will turn the engine over, and when you let go of the key it will return to the on position.

Does the truck start and die within several seconds? If so, that is more then likely your oil pressure switch doing it's job. Although it could be IAC or TPS or a few other things. The oil pressure switch will allow the engine to start becuase there is no oil pressure (engine not running no pressure), however if the pressure doesn't build it will kill power to the fuel pump. Its a safety thing so you don't waste your engine.

The oil pressure sending unit and guage are two different things, both should be located near each other and usually near the oil filter or oil filter remote thingy (forgot technical term at the moment) on the engine block. Look for 2 wire harnesses. One for each. Buy a new oil pressure switch so you know what it looks like. Wrap some oil/gas pipe thread tape around the threads before you install it.

You positive the engine is getting the proper amount of fuel during start up? Don't have a plugged fuel filter? I just replaced my fuel pump/sender unit. I could hear it run and it had gas. However it wasn't pumping any gas. I disconnected my fuel filter on the gas tank side to verify it wasn't pushing any gas. Don't watch it, just look for the puddle on the ground.

It would help if you specified which "car" were talking about. What I posteed is general for the s-series blazers.

 

No it does not start and die. Well, when I had sprayed a little carb clean into the intake it acted like it was going to start, but died just as quick. Just turns over.

No, I'm not sure that fuel is being delivered at all. I took a stab at taking one of the inbound lines off the CPI module. Didn't see any gas being pushed, but not sure that was a real test.

Tonight, I am going to replace the fuel filter. Probably needs it anyway. I'll also run that test to see if gas is being pumped to the filter. If it is being delivered to the filter and after the filter is replaced I will try to start it again.

If it does not start, I bought a pressure gauge to hook to the injector module to test for proper pressure. But I won't open it until I've exhausted the other test of course.

I will update tomorrow any findings I get out of tonight.

Are you saying that the oil pressure sending unit might need to be replaced? To me it seems it did it's job and shut the vehicle down. Now, with proper oil pressure, I would think it would allow the vehicle to start. That is why I'm going in the fuel filter, fuel pressure, fuel pump direction. There are no reset buttons on these units are there? Like on my toyota, there is a switch/cable thing you have to pull in the cargo area glove box if you were to be in a slight accident and couldn't start the car because the fuel shutoff device had gotten tripped. Of course it's been a while since I've looked at it, and it may have been my 92 thunderbird that had it. (That is a whole different story I know, but I'm just wondering if there is a switch somewhere on this blazer that I have to physically reset and I just can't/don't know how to find it, there isn't an actual reference to it in the owner's manual or the haynes I'm just guessing)

By the way. I realize I sort of highjacked arbowman's thread. Would/Should I have started a new one??? My own?? I figured since it was a similar interest I would just jump in the middle... No offense I hope!!