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Chevy Blazer Starting and Stalling Problems



  • jlflemmonsjlflemmons Posts: 2,242
    Blodie, If you have a '97 with the 4.3L V6, it doesn't have a carburetor, it is fuel injected. If you are pouring fuel into the throttle body, you are bypassing the fuel injection and all of it's sensors. Not a good plan. So, your description of the problem is a bit confusing.

    With regard to the problem, it could be a bad crankshaft position sensor. If the sensor doesn't "see" the engine turning, it shuts off the fuel flow. This sensor is mounted down by the crankshaft at the 7 o'clock position facing the engine.


    How many miles on the engine?
    Did the problem come on suddenly, or worsen over time?
    Is the "Service Engine Soon" light coming on when the engine is running?

    The fuel pump circuit is designed to pressurize when you first turn the key on, but will only continue to run if the CPS tells the computer the engine is turning. Give us some more detail and we will try to help.

  • Blondie16 I have a 98 my problem would be hard to start everytime crank for awhile. After some research I found alot of people have problems with the spider assembly and fuel pressure regulator or just one of the two. My problem was the fuel pressure regulator. There is a guy on here that tells you the whole step by step of the whole process and pictures. If you cant find it you basicly have to remove the braket for the fuel line back of plentum driver side you will see two silver lines. remove the throttle and cruise cable and brakets. the air cleaner, the throttle body the bolts around the plentum I beleive its 13 for the plentum. It sounds harder then it really is. I replaced mine in about an hour. If you have the money replace the spider assembly it houses all the injecters or clean , replace the fuel pressure regulater put al back together and it should do yiou some good it helped my sh runs great now. Let me know if you need more detail Ill keep looking.
  • Thank you, it has 150,000 miles on it and the engine light is on when it's running. It wasn't when this first started but now it is. This starting happening slowly, I would go out in the morning to start it and it would take me a couple of times to get it to crank, but then after a week it turned into about five minutes of trying before it would start. Then it just wouldn't turn over at all. And would this also cause it to cut off when I slow down to stop or slow down to make a turn?
  • Thank you, we are going to check all of this out and hopefully with all of the suggestions I'm getting something will work.
  • jlflemmonsjlflemmons Posts: 2,242
    okay, now we are getting somewhere. Typically, when the crankshaft position sensor fails the engine shuts down. Turning the key off, then back on can clear the "fault" and let the car start.

    But the description you detailed above with the problem getting worse and worse does sound more like the fuel regulator or fuel spider assembly. GM did have a problem with regulators "leaking down" where the engine would get flooded when not running, making it very hard to start, and causing it to run rough at low speed. At higher engine speeds the engine would run rich, but still run.

    If you have an Autozone in your area, they can read the code that has been set in the computer and tell you where the problem is occuring. Any time a service engine soon lamp is lit, a code is set in the ECM indicating what is wrong. Let me say here that you have to put some thought behind what it tells you. I have seen folks replace oxygen sensors because thats what the code said was bad, when the problem was a damaged wiring harness. I had a car that twice indicated the throttle position sensor was bad. Shop replaced it twice under warranty before the mechie noticed that one of the contacts wasn't snapped into the connector and was only making intermittent connection. Once fully seated, the problem never occured again.

    So, get the code checked, and see if you get a heavy fuel smell from the throttle body after the vehicle sits overnight. That will give you an indication that the fuel regulator is leaking.
  • Ok, I didn't check my email until after I went and bought the crank shaft sensor and put it on. Well that's not the problem so I took it back and bought one of those Haynes books and we still can't locate the fuel regulator or the fuel spider assembly. And I can't get it to an Auto Zone safely because the closes one to where it's being worked on at isn't in a good area. By the time they got done checking the code I may not have any wheels. Could you tell me where we can locate these two things or is there something I could look up and it show me?
  • rddivarddiva Posts: 1
    hi im a new member "of the club" i was reading this message and your reply.
    can you tell me if i would have a canister on my 1993 s-10 blazer 4.3 vortex? if so would this canister prevent normal performance of the vehicle, such as cranking / running? the vehicle will crank{not consistently} but when it will you can maybe go a mile && it shuts down. if i had to describe , it feels like trash in the fuel line/obstruction. however, let it sit for an hour && it cranks up. i have replaced 4fuel pumps{3 nock-offs & 1 ac delco} list of items replaced is excessive: fuel pump assembly, fueltank, relay,fuel filter, cpi spydar assembly, oil sending unit{my oil pressure showed low @times when full}, o2 sensor & ignition module,. the fuel pressure is excellent & consistent. we have got a trouble code # 43 electronic spark control but haynes manual is vague on the subject. i know you re thinking all that for a 1993? yes with a rebuilt motor with no more than 30,000miles. we cant give up, however, we are getting frustrated!! please ANYONE can you help.
  • jlflemmonsjlflemmons Posts: 2,242
    The regulator and spider assembly are in the intake assembly. Let me see if I can locate a picture and I will post a link.
  • ok the regulator for the fuel is between the intake were your air cleaner goes into the engine and the bottom intake. all you have to do is take the air cleaner assembly off then the throttle body and the plugs around it also the cable for throttle and cruise after this you will see the black dome like plastic piece the plentum, the haynes book does not get into detail so what i am saying is start to tear down the top of the engine. if you need more help e-mail me at [email protected] I will try to find the post with pictures that helped me.
  • isoiaisoia Posts: 6
    Always seem to have problems after going through the carwash. Just replaced the fuel pump, broke down on the freeway, ignition wasn't making an electrical connection so my key was stuck, and I had absolutely no power. The problem was I needed to clean the two-way fuse underneath the battery. It ran beautifully since then. NOW . . . I have a problem with the fuel filter! Again, the problem arises after a trip to the carwash. I've replaced the fuel filter, but the hose connecting to the top of the filter is partly busted, and doesn't snap into place with the new filter. It is the RIGHT part with the right accessories. The previous owner used two O-Rings for the filter, but I've decided to use just one, and it's left me with a major fuel leak. Has anyone encountered this problem? Any suggestions, before having to replace the entire fuel line?

    Thanks, iSOiA
  • isoiaisoia Posts: 6
    Thanks for your response. My Dad ended up securing it with zip-ties. So far, so good, it's still holding together. But I'm still having the same problem with the engine cutting out on hot days. Runs good with no problems during the night while it's cooler. My Dad's conclusion is a vapor lock. Can I solve this problem without having to take into the shop? I also heard from another mechanic using wooden clothes pins to help lessen the heat in the fuel lines.

    Mike | [email protected]
  • duntovduntov Posts: 133
    Clothes pins? Please.....

    The fuel line to the filter is a hard connection on the driver's side of the frame.A hard connection is necessary because of the high fuel line pressure used with modern fuel injection. The "vapor lock" problem does not occur anymore. That was in the early days of carburated engines and has not occured since the mid-1960s and then it was caused by underhood temperatures. If it were a problem today, you would hear about vapor lock more often. You must solve the fuel line to filter issue and zip locks are only a temporary spit and bailing wire solution. Replacing the fuel filter can be troublesome due to the location and the hard connections but those type connections must be made. If the fuel line is damaged, the damaged area must be cut out and replaced with section of new fuel line and brass connections.

    The problem is most likely electrical. Start by replacing the fuel tank relay. They are cheap. The relay is located under the dash and is a plug-in connection. The fuel pump relay is AC Delco 15-50688 and it costs $9.00.

    A restricted catalytic converter will cause the exhaust O2 sensor to tell the ECM (Engine Control Module) to make the engine do strange things. There is no way to check for a restricted catalytic converter except to replace it. If someone wants to test a catalytic converter for a restricted condition before they replace it, the only thing that can be done is to replace it with a temporary "test pipe" to see if the vehicle's performance improves. An emmissions test will not indicate if the catalytic converter is restricted. Factory catalytic converters are expensive. Since they are required on vehicles by the federal government, the new car manufacturers must guarantee them for 80,000 miles. The cheaper aftermarket catalytic converters that are installed on pre-owned vehicles must be guaranteed for only 26,000 miles. Your O2 sensor in the exhaust pipe ahead of the catalytic converter could be bad but are easy to replace. An O2 sensor is AC Delco AFS 105.....$65.00.

    You appear to have good fuel pressure. However, the fuel pump module assembly cost from $360 to $400 for a 2000 Jimmy, depending on the brand plus the labor cost for installation. I doubt if that is your problem.
  • I'm having starting issues with my 1999 Blazer. I believe the problem could be a regulator or another fuel system component. Did you find any pictures of the regulator and/or the spider assembly? Did replacing either of these components solve your starting problems.

    My Blazer starts but it usually cranks quite a few times before it starts. It never used to do this and it is getting worse. It always starts and once it is running it runs great. It just takes a few tries to get it started.
  • jlflemmonsjlflemmons Posts: 2,242
    I couldn't find postable photos, but the assembly is inside the two piece intake manifold. I believe the regulator is in there with it.

    "Spider" is a good name for this assembly. There is a large injector 'pump' with six tubes, each one running out to a cylinder.
  • He still can't find the fuel regulator on my blazer but he did find the map sensor is it around that? Can you find and send me a picture of it?Or tell me ( in detail ) where it is? I really need this fixed I haven't been able to drive it since June and I don't have alot of money to put into it so I can't take it to a dealer.
  • duntovduntov Posts: 133
    The fuel pressure regulator on 1987-1992 VIN-Z engines with TBI (Throttle Body Injection) is part of the throttle body assembly and can be replaced separately from the TBI assembly. AC Delco #217382 ( GM -17112399 ) The cost of the fuel pressure regulator is from $84.35 to $182.21 depending on where you purchase it and if you get a discount.

    On 1992-1995 Vin-W engines , the fuel pressure regulator is part of the CPI (Central Port Injection) assembly which is located inside the upper intake manifold plenum. You must remove the upper intake manifold plenum to access the CPI assembly. The fuel pressure regulator on those models cannot be replaced spearately from the CPI assembly. The cost of the CPI assembly is more than $500. There is an alternative to replacing the entire CPI assembly when the fuel pressure regulator fails. You can now purchase a new fuel pressure regulator separately from the CPI, It is offered by Dorman as part #55162 and it cost $47.95.

    I knew it was just a matter of time before some company would offer a fuel pressure regulator separately form the CPI assembly.
  • I have a 97 blazer 4.3 liter v6 vortex where would it be on that? I have tried to look up pictures of one but the pictures seem to stop at 95.
  • isoiaisoia Posts: 6
    I had the same problem, especially during the HOTTEST days of August. Though I do suggest checking your fuel lines underneath the driver seat. My problem was the plastic connectors were damaged. I had them replaced at Chevrolet, $700 for one (1) fuel line. It runs fine now, but I believe the problem still not fixed. When I'm at a complete stop, and when pressing on the accelerator I can feel the engine slip.
  • I have a 1995 Chevy Blazer LS, 4.3, automatic. It had a bad miss in it so I done the typical tune up (plugs, plug wire, air filter, fuel filter, oil change, oil filter). It took some of the miss out for about 3 weeks, now it's back to missing even worse now, :mad: so I dropped the gas tank and cleaned it out, put another fuel filter on it (cause when I replaced the first one it was really bad). I know the fuel pump is good and I know its getting fuel. I have replaced the relays so I know they are not the problem. Sometimes it starts very easy, sometimes it don't...sometimes it runs great, sometimes it don't. It has never completely died on me (yet) but it misses but not all the time. You can drive for a few miles and it runs great then it will start jumping and missing. If anyone has any suggestions.. :confuse: ..that would be great...thank you!!
  • Is this a backfiring (ignition) or stalling (fuel system) type of "miss"? And when does it do this? Does it happen mostly at idle, at highway speed, when the engine is just started, when fully warmed up, just when it's raining? Can you give more info? And have you had the fuel pressure actually measured?
  • It is not backfiring, it has only completely stalled on me once, but fired right back up. It misses at various times, sometimes when your at idle sometimes when you running 40 to 50mph. I have noticed it does it more when it is warm but it also sometimes misses when you just start it. It does not miss all the time. I have not had the fuel pressure measured. Sometimes you can drive for 4 or 5 miles before it starts missing then you give it a little more gas and it quits missing for a bit. I took it to a garage today and explained to them what was happening and told them everything I have already done and they were also stumped. The guy at the garage (which didn't seem to know what he was talking about) said the catalytic converter may be plugged up, but from my experience, when a converter plugs up and you give it gas, the miss gets worse, so I really don't think thats the problem.
  • Check fuel pressure and if it looses pressure change the fuel pressure regulator. I would also clean the spider assembly while all of the components are taken apart.
  • jlflemmonsjlflemmons Posts: 2,242
    Are you getting a Check Engine light? There are any number of sensors that can cause the ignition to go intermittent and misfire.

    In my history, there have been two occasions of an intermittent crankshaft position sensor, but at $60, you don't want to swap this one unless you know it is bad. Stores a code, but I can't remember off the top of my head what it was. And if the lamp doesn't come on, the code won't be there anyway.
  • What are the signs of a catalytic converter plugging and backfire sound from the cat...? Fuel filter changed, new fuel pump, 02 sensors before cat has been changed. po131 and po151 came-up before the changes. No rotting egg smell.
  • gg1328gg1328 Posts: 16

    I have a 1994 Bravada 4.3 CPI Engine - Vin W, 135,000 miles on it. I own the car about 4 and a half years and is used mainly as a 2nd car and in winters. (4 wheel drive vehicle)



  • sounds like a leaking central port injection unit is it tbi or carb if it is tbi could be leaking on top of plenum which would cause fuel smell in the oil. I think this is the year that has the fuel regulator problems on the cpi or the fuel lines running through the plenum, but i wouldn't start it with plenum off but i would turn the key on so the fuel pump runs so you can look for a leak. They sell fuel a regulator repair kit and gm sells fuel line repair kit. One way to test it might be to put a fuel pressure guage on it turn the key its supposed to hold around 50-60 psi for 2 min if it bleeds off you know you have a leak. Also if you do have a leak it should be very noticable when you take off upper plenum should be black if there is clean brown tint spots sign of where your fuel is leaking. I have a 98 blazer thats how i know this stuff its having starting probs need to replace ignition control module, or distributer cap
  • gg1328gg1328 Posts: 16
    Thanks for your quick reply. I'm trying to locate the CRANKSHAFT POSITION SENSOR. If you could please be specific about its location. Thanks.
  • use to start beautifully. got in and it started and died and started and died tehn clicked like battery dead. Replaced battery and banged on starter, still clicked. Took it to mechanic and he said probably starter but instead of me buying it and it not being it he tried to turn the engine manually and did so but said that it turns counterclockwise but when he turns it clockwise it goes for a little while than gets to where he can't move it any longer. Why? Should I replace the starter? What about all the ppl on here that say the cylanoid or relay or flywheel not lining up? They say to grease up spark plugs and replace them. I am a single parent with no $ for a new car. please help.
  • jlflemmonsjlflemmons Posts: 2,242
    Look at the crankshaft, bottom pulley, front of engine. There should be a small wire harness coming from above and plugging into a small device at the 7 o'clock position as you face the engine.

    That device is the CPS. If it isn't there, you now know why the car won't start!

  • gg1328gg1328 Posts: 16
    Thank you very much!!! I will look for it on the weekend.

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