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Chevy Blazer Fuel Pump and Pressure Regulator Problems



  • 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: 2,240
    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?
  • nmonk83nmonk83 Posts: 1
    a shot of ether and runs for a few seconds then quits,i have had 7 pumps in it. the last one was put in 2 months ago. any thoughts?
  • I have a 96 s-10 blazer that had what sounds like the exact same problem. they changed the fuel pump, the filter they checked the regulator also it turns out it was something called the spider injector im guessing its the fuel injectors they changed that and it started right up i don't know if the 2000 is much diffrent from the 96 so check it out might work for you too.
  • I have an 02 Blazer with 150,000miles on it. It had been doing the same thing, Real tough to start then it would only start with ether then to the point where I was killin the battery and having to recharge it before she would start.. I knew it was something in the fuel system but nobody could figure it out. I had changed the fuel pump and fuel filter and it was fine for a couple weeks then the same thing again. So a family friend was over and has a 96or97 blazer I was telling him about the problem. He said that he had gone through a few fuel pumps before he figured out what caused his to do the same thing. Turned out that he had to replace the spider injector set-up because it is plastic and had cracked therefore it was leaking fuel into the manifold. To do this repair you need to take off the upper manifold, while you having the upper manifold off you need to also changed your fuel pressure regulator which is also under the manifold on this vehicle. I have mine in the shop as I am writing this so I should have it back early next week... I will follow up on this post for anybody else having a similar problem.
  • bonedog16bonedog16 Posts: 1
    i have a 96 blazer it pudders and hesitates to go after i stop then go like after a stop light or stop sign but it eventually kicks in then its fine like if im the highway its ok my truck doesnt have a catylac converter it has a flex pipe wich is hoocked up to a pipe that connects to my muffler wich the pipe going from my muffler to the flex pipe isnt quite connected all the way its clamped but not all the way and my exsaust is loud my cousin says it might be because i dont have any back pressure im not sure really also my gas and temprature gauge doesnt work i checked all fuses and they seem fine i dont know how much gas i have in it or wut the temp of the motor is also there is a really bad squeek noise coming from my passenger side maybe a ball joint or idler arm not sure wut do i do
  • redddogg1redddogg1 Posts: 2
    I have a 1995 blazer ..For some reason I'm not getting power to the fuel pump .. Cant seem to understand why ..I know it works fine because I used some wires test it .But plug it to the harness it don't work ..Doing the work myself don't have the money for a Mechanic!!!!!
  • jondevilsjondevils Posts: 1
    Replaced fuel pump on my Blazer bc thought it was bad (which it was not). Have new pump in but still won't come on. Checked all relay switches and fuses they are all good. Checked connections to pump all are connected and each wire is getting fire to them. Blazer will turn over but will not start and fuel pump won't come on at all. Can put fuel in throttle and it will start but shut off as soon as it burns fuel off. Have no clue on what else could be causing the fuel pump to not come on. Please help lol. Please post on here and please e-mail me as well at
  • stealthnystealthny Posts: 25
    I have a 1997 Blazer that I have been trying to fix for 6 mos. It just wont start on its own. I have repalced the pump ( which they said was bad but never pressure tested at the filter. when i pour gas down the carb it starts right up but will only run as long as the gas I pour in lats then stalls. someone told me that means the injectors are out of sinc. I am trying to replace the fuel filter now. nobody has tested the pump pressure other then holding down the FPV and saying there is alot of pressure there. anyone ever of the injectors being out of sinc
  • 2002 Blazer V-6, 4WD, auto. The gas gauge floats back and forth. Been doing that since a few months after I bought it 2 years ago. Started getting a double code about 8 months ago, (evap code, and I don't have the code here, but I think it was P0049 that suggested evap system). Could it be a vacuum (line) problem.

    I have a friend with a 1998 (or 96) that has the same problem. They've replaced the fuel pump 3 times but it (the CEL) still happens.
    I've replaced the gas cap and the purge valve but the codes keep coming back.

    If it's happened to 2 vehicles, it's probably happened to more. Does anyone have experience with this problem?

    Thanks, Rick
  • jlflemmonsjlflemmons Posts: 2,240
    See the answer I posted to your question in Maintenance and Repair.
  • Do you know what page or have a link to the page?
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