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Chevy Blazer Fuel Pump and Pressure Regulator Problems



  • It is your fuel pump. they need to pump at least 60 psi to start your Blazer. if you pour a little gas into the Throttle body it will run just fine, but you will need to do this every time, I have the same problem with my 96 Blazer and have been doing this for 6 8 months now.
  • ok thanks whitemfox,
    So now do I have to drop the tank to replace it. and if I do should I replace the sending unit as well. My gas gauge doesnt work but that could be almost anything. I will tell you why. I can find a replacement pump for approx $75.00 but both costs approx $135.00 to $400.00.
    Also I did pour gas into it one time and that did work although it raced like crazy for a moment. but the next time I tried that it still wouldnt start
  • jlflemmonsjlflemmons Posts: 2,242
    Yup, that's why I was asking about the fuel pressure. Once running, you can sometimes run with low fuel pressure, but not always as good as it should. Takes a lot of pressure to make those little injectors squirt right!

    Fuel pumps from the 96-98 era in the Blazers seem to be troublesome. See a lot of posts on these. Had one fail in a '96 Sierra as well as a '04 Yukon, though both of these were a hard no-pump failure.

    The sending unit for the fuel gauge is part of the pump assembly. It can be purchased separately, or together as one unit. Be sure you get the correct pump assembly. The 2door and 4door have different tanks and use different pump assemblies.
  • Good morning

    My 1997 Blazer when tested at the fuel pressure regulator valve shows pressure of only 31 psi. Once I get it started it seems to run fine. but when I let it sit overnight I have to try to get it started about 8 -15 times. My mech says its the fuel pump. couldnt it be the fuel pressure regulator? Is this where the pump pressure shoiuld be tested

  • Sounds like your fuel pump is going out. I had same problem last year around this time, I would get off work in the morning to find myself sitting in the parking lot for an extra 10-15 minutes trying to get my dang blazer started up. A few weeks later it was in my garage and wouldnt even fire up. I had it towed down to the mechanic and he said it was the fuel pump. I couldnt believe it because the one I had in there at the time was only like a year and half old. But this time I replaced it with an actual pump from GM I got at the auto dealer. Have you changed out fuel filter at all since you have owned the vehicle?
  • Hello

    No I have not changed the fuel filter . I would of thought that the mech would of checked that first. Could it be the fuel filter?

  • With just 31 psi your lucky it runs at all. I would get the fuel pump replaced quickly before you get stranded. and believe me fuel pumps go out anytime even while sitting at a stop light :(
  • OK thanks I will do that. Should I replace the sending unit also?
    I can buy a after market pump only however I havent heard alot of good about them.

    The truck runs oddly enough great. no loss of power and once I get it started in the am its starts all day. Thats why I was confused
  • jlflemmonsjlflemmons Posts: 2,242
    Go with the GM pump. For whatever reason, there have been a lot of posts about aftermarket pumps failing prematurely. If your mechanic is only getting 31psi at idle, it isn't likely the fuel filter as the flow rate is very low for these engines at idle, and fuel filters are more likely to drop pressure at higher flow rates. When changing the fuel pump, ALWAYS change the fuel filter. With regard to the sending unit, strictly up to you as it has no impact on the pump function. Other than telling you there is nothing left to pump, that is. :)
  • Thank You

    I am sure you will be hearing more from me as this has really become a problem truck. Now it seems the computer will not read It will only say "not ready" I hope it just needs more miles on it to reset. If I cant get it inspected I am sure not going to put a fuel pump in it. I have already replaced the battery,starter,rear u-joints and had 3 electric shorts fixed.

    Thanks for all your help and time

  • Good morning

    Well I knew I would have more questions. This is a 1997 2 dr blazer.
    Instaed of droping the tank to replace the fuel pump can my mech cut an acess hole in the back deck to get at it? He says he has done this on other trucks? I believe the sending unit and pump cover are in the middle of the tank.


  • jlflemmonsjlflemmons Posts: 2,242
    That's gonna be one big hole! The pump/sending unit is a rather large assembly. Dropping the tank on a two door is not that difficult, and you might have a sealing issue cutting out that much of the rear deck.

    Not to mention how easy it would be to damage the top of the tank while cutting the hole.
  • What is the black box underneath the in left back corner of my blazer it looks like gas lines run into it and what would happen if I disconnected the lines and ran them directly to fuel filter
  • jlflemmonsjlflemmons Posts: 2,242
    no no no no no!

    That is a evaporative vapor canister. Needs to stay connected, and no pressure or fluid is going through there. It is for "scrubbing" fuel vapors, emissions item.
  • OK guys I will try this one more time. I have a 1997 Blazer. It takes me 8-10 times in the morning to get this to start. If its warmer it takes less time but still doesnt start right away. I do hear the fuel prime. can a fuel pump prime and be no good? I do have spark. I can do this for a few weeks and then cant get it to start at all.
    I did pour gas into it but it wont even start to burn the gas off. Can A fuel pump be bad if you hear it prime? I looked at the gas reg valve and my problem is there is no rubber hose on mine. There are 2 chrome lines coming into the top of my manifold rubber lines to remove and check for gas in them. Does the fuel pump have a check valve to stop gas from returning into the tank? where can I get a gas reg valve tester to check the pressure there. One last thing. When I turn the key on I hear the pump but it will continue to run for a few seconds after I turn the key off.
  • It is your fuel pump they should be pumping at 65psi to start them but once started they run good at around 50. I have a 96 Blazer which did exactly the same thing as yours, warm/cold not starting, pouring gas in. Now one year later., I stll have to pour gas in to it but it still running. cannot afford a new fuel pump at this time.
  • I know what you mean but once mine wont start, It wont start or even try and burn the gas I poured in. It wont start at all. I might even settle if mine would start with pouring in although that would be tough here in upsate NY I would get the pump fixed If I was usre thats what it was
  • Take it down to a mechanic and tell them to gauge your fuel pressure. if its lower than what it should be, replace the pump. Also, how often do you change your fuel filter?
  • I just bought it in DEC with this problem so I have never changed the fuel filter you think it could be something as simple as that?
  • I have a 2000 Blazer (4.3l) with a little over a 100,000 miles on it, just recently when I tried to start it up, the fuel pump did not "whine" like it normally does. A friend told me to bump the fuel pump with my hand and try it again. Bingo, worked like a charm for about 2 weeks. Now I'm back in the same boat, I tried bumping the fuel pump again, but it would not work. I dropped the fuel tank, pulled out the pump assembly and straight wired it and it worked fine in my hand, I then hooked the fuel harness' back up to the pump and it works like it should.

    Could it be the brushes in the pump, and by me messing with it, jarred it enough to make it work, or could it be a wiring issue somewhere?
  • jlflemmonsjlflemmons Posts: 2,242
    Most likely the pump motor is going out. The "tell" is the whacking of the bottom of the tank and the pump running again. Classic in tank failure mode, one that has been around for many years.

    Hate to tell you this, but there is a new fuel pump in your (very) near future.
  • i have a 1998 chevy blazer. my fuel pump went out. so i changed it and changed the pugs and wires. now it wont start so i use some starting fulid and it runs fine after that. been doing that for 3 after a bad ice storm it dont wanna run it back fires thu the intake and when i give it gas while driving it wants to die and has no power i took it down and had auto zone run the check eng codes and i got back too rich and maf so i changed the maf and still nothing.
  • duntovduntov Posts: 133
    Replace the ignition control module in the distributor. Always use new screws to hold it in place because they serve a the ground. The old screws can rust and lose the ground for the ICM. Always use silver thermal transfer compound paste on the ICM heat sink where the ICM rests on the heat sink in the distributor. It is sold on AMAZON or at any computer electronics store.

    NEVER use dieletric silicone grease....dielectric silicone grease is a insulator. "Dielectric" means insulation. Dielectic grease will reduce the conductivity of heat sink connection and electronic connectors of all types. Silicone dielectric grease should only to be used as a sealer in the Weather tite electrical connectors and not on the metal parts of the connectors. ..
  • on my blazer the gas hand will say it has about a quarter if a tank, but when it reaches a quarter of a tank it is actually almost empty...its like its a quarter of a tank off...what is causing this and how do i fix it?
  • mntnresqmntnresq Posts: 2

    I have a '98 Blazer with about 140k on it. While I suspect a fuel prob, not sure it's a pressure issue. The pump runs the prime cycle fine, and it starts and idles with no problems, hot or cold. It has however, gotten increasingly bad with loss of power at more than about 1/2 throttle. It ran and accelerated fine as long as you stayed about 1/2 throttle or less, any more, and it would just fall on it's face. No, sputtering, no misses, just make more noise, and power would drop off dramatically. SES light was silent, though I know the fuel pump will not normally throw a code.

    So, last night, I started it and let it run for a while to warm up while getting ready to go somewhere. Got in and took off, and now if you do much more than barely crack the throttle, it spits and sputters, and has no power at all. I limped it home at about 15 mph. SES did come on, though I have not been able to pull a code, since I am afraid to try to drive it anywhere which can scan it. If I had to guess, it's going to come up as a rich condition. Also have not been able to check the fuel pressure.

    My thoughts are leaking CPI, MAF, TPS, or CPS/module. Throwing parts at it is not practical, nor viable with my current cash flow. Anyone have any other thoughts?

    Also, I did replace intake gaskets about 2-3 months ago, during which I cleaned the throttle body, MAF, MAP, etc. The CPI did not show signs of leaking at that time.

  • mntnresqmntnresq Posts: 2
    Well, seems I was wrong. Just got in it to try to move it to get the other truck out. No prime, no start. Guess I shoulda seen it coming.. did the unthinkable, and filled it up when it was really low..
  • 97blazerowner97blazerowner Posts: 1
    edited March 2010
    I understand from other discussions and online research that to get to the fuel pressure regulator on my 97 Chevy Blazer I must first remove the upper intake manifold. Does anyone know why I have to drain the engine coolant when removing the upper intake manifold?
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