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Chevy Blazer Fuel Pump and Pressure Regulator Problems



  • Install a manual switch to disconnect/reconnect the fuel pump without having to drop the fuel tank to get to the wiring?
    Modern Detroit engineering is a validation of the old adage that cousins should not be allowed to marry ... their mothers.
  • lady wants me to fix her Blazer. Told her sorry, it was trashed at the factory during design and manufacture. Who builds this (cant find an angry word that is bad enough).
    Everything you need to get to is under a bunch of other stuff, you need fingers like needlenose plier and elbows like swivel socket adapters.
    The fuel pump is list at Napa for 324 $ and change, plus taxes of course.
    Fuel pump runs for two seconds and quits - pressure is built but NO GAS ARRIVES AT THE ENGINE!
    Have disconnected gas line from filter and from fuel input at engine - compressed air passes freely.
    Am about to install an inline impulse pump to see if the vehicle will run on that. Advise lady to sell this so someone that she really hates and has the punishment coming - and buy a Dodge 74 van. Fixable and reliable even in the desert.
    Modern cars are trash - and their design lends validation to the adage that cousins should not be allowed to marry - their mothers.... :mad:
  • repairdogrepairdog Posts: 948
    GM pump is designed to run for 2 sec as the prime as pressure on 96 up should be tested at the fuel rsil port and be min 60psi, then drop 2-3 lbs as the pump shuts off. Fast drops indicate a bad regulator or pump. So, after the 2 sec prime (note: then key off for 10 sec it will run again for 2 sec) no gas at where? What year? 96 up are injected diff than 95 earlier with CPI and earlier with the throttle body injection, back to a carb. Let me know what you need.
  • wuddarushwuddarush Posts: 3
    My 98 chevy blazer was running fine. I drove it to work and when i tried to start it to leave it would not start. It sounded like it was the fuel pump was not pumping. I turned the key on to listen for the HUMM noise of the fuel pump and i couldnt hear it. A friend from work told me to try banging on the bottom of the gas tank so I went out and banged all along the fuel tank with my hand/fist and then i got back in and turned the key , then i heard the HUMM kick in and long behold it started right up. Not sure if this might help anyone but it sure helped me to get it back home. Still probably need to replace the fuel pump but at least its not stuck at work.
  • repairdogrepairdog Posts: 948
    Correct, pump going or bad connector on top of tank.
  • My 2000 Blazer was running fine when I went to work a couple of days ago. When I got in it after work it wouldn't start. I couldn't hear the fuel pump running so I assumed it was the pump. I took the tank apart and got that same pump running for a day and then it happened again. It rolls over but will not start. I put some primer in the air intake and and it ran like that. I replaced it with a new pump and a new fuel filter and now have alot of fuel pressure but it still won't start. I am getting fuel pressure up to the engine at the pressure check valve area. I have tried everything I can think and now I am lost as to what to try next. Does anyone have any suggestions?
  • My Blazer started but I'm not sure for how long it will run. Last time I got it running for only about 24 hrs by replacing the connector that accepts the clips from the outside and the inside of the tank. This time I installed new wires (black and gray) inside the tank, from pump to the connector that sits beside the fuel lines and I am using the same pump that the Blazer first broke down with. I still don't quite trust it for long distance driving because I'm afraid of getting stuck out in the middle of nowhere.(I live in the sticks in the far Canadian North). Hard to find parts up here so I always have to trouble-shoot every problem before buying expensive parts. I hope it stays running from now on. By the way, is anyone reading this?
  • I have noticed lately, my blazer seems like its starving for fuel. one case, when I get below half a tank, i try to accelerate, but the RPM goes down and it doesnt even want to move. Or when I go up a hill, I cant even keep up with the speed limit! I changed fuel pump in tank 2 months ago. I changed fuel filter a month ago. When I fill up the tank completely, then it seems to do ok, sometimes. I had to fill up today at 3/4 of a tank and it still decided to not give any power, and yesterday it dipped below 1/2 tank and had to pull over on the side of the road and get a 5 gal can of gas to fill it. Is there another fuel pump besides the one in the tank that may be going bad? when i search fuel pumps on google, it shows me a different one that goes in the tank. its getting frustrating not being able to move on the raod and fueling up all the time. Any help would be wonderful!
  • jlflemmonsjlflemmons Posts: 2,242
    Something that specific may be a dealer only item. Their books (or computer screen) should show the part.
  • jlflemmonsjlflemmons Posts: 2,242
    Ah, your friend has taught you the GM Tank Kicking Two Step. A new fuel pump is in your future. This is a very common method of getting an intermittent fuel pump off it's butt and get you back home. :shades:
  • i have a 2000 jimmy , replaced fuel pump, filter, i am not getting fuel to the engine im guessin. no pressure at port and will start with starting fluid sprayed at filter im guessin my spark is good. i do know i get fuel from the tank and to the filer becouse i have tested that.any ideas or suggestions for me id like to fix it if i could. and i do have to think about the costs here too so any id like to do all i can first
  • A night before i set on a journey from Switzerland to Germany my car show yellow warning light which warn about fuel, power etc the symbol look like a videocamera diagram.

    After about 3 hour drive the car stop to accellerate. I listern to the fuel pum sound it sound fine but road patrol said the fuel dont run to injector. What can i do before i buy a new pumb whch cost about $1150 equivalent in Swiss Franc (Sfr.1350-)

    Befoe then i notice my car jeck for fuellike when the fuel suppply is cutting mostly when i break in a traffic light and some time it run so low that it switch off.
  • You said the pump was replaced...I think you have a 4 door Blazer pump installed in your 2 door Blazer. Ain't the same... but it will fit and look the same..The 2 door has a module (the white thing on top where the hoses connect) with a sticker marked SGK which is correct for a 2 door(19 gallon tank) A 4 door has a module marked TCH (18 gallon tank). A 2 door tank is mounted between the back frame rails...A 4 door tank is mounted on the drivers side to make room for the spare tire.
    If someone sold you a pump that is supposed to fit got ripped off.
  • You such a great help. I have ordered a new fuel pumpfollowing your advice..God Bless you. Plsdo you know where i can buy a good repair manual? or where to download one for free
  • I have a 98 Blazer I bought a few months ago... I have been getting very frusterated trying to figure out this problem.

    The truck feels like I'm towing a trailer all the time, however the odd time it seems to lighten up. All the bumps on the road are very hard, very rough ride and when I go over bumps it bounces all over. Now when I put it in 4WD and hit the gas, I hear a cluck from the front left wheel. It almost sounds like a CV joint on a FWD car. But louder and harder.

    I feel like these problems are all related to the same thing, but I can't find it. I've checked if any of the brakes are draging there all good. It possibly needs an alignment. If anyone can help, please do before I sell this thing!

  • rdp2rdp2 Posts: 1
    I just came across this old message you left for a guy who had replaced his fuel pump. i've got a 97 2dr Blazer, just replaced the fuel pump, and she won't do any more than idle. very little pressure at the pressure valve on the rear of the engine. the pump was listed as a MU112 E3953M. do you know if this was this the wrong pump? i don't remember what sticker was on it. sure would appreciate any help. thanx
  • Ive been having problems with this for truck for months now. I would be driving down the street and the car would just stall. No warning it just cuts off. A mechanic replaced the modulator.(Think thats what its called) It ran fine for about a week and a half. Then it started again. Only now its stalling all the time. I couldnt make it down the street without it stalling 3 or 4 times. The fuel pump would come on and stay on. It hums the entire time the car is on. Ive smelled fumes also. Now the truck doesnt start at all. It will turn over but wont start. Like it cant get gas. Had mechanic replace pump about year ago. Could it be the fuel pump or something else????

    Thanks in advance!
  • Dont know if ur still trying to find out about that fuel pump but u can go on ebay motors. They have the two door listed as MU1063 E3954M. Hope that was helpful if you still need the info.
  • bitterbitter Posts: 22
    The fuel pressure regulator on the 4.3 eng. is located @ the back of the intake manifold, behind the throttle body. The manifold has to be taken up to be replaced.
  • Pump not working
    Replaced the pump, lasted two weeks.
    Tried starting it everyday for one week No humm). Seventh day it started, why I have no clue.
    two days later it was dead again.(no humm)
    Got under the truck, unplugged it, checked the plug for hot,(GOOD).
    Checked the ground (GOOD), which is on the frame in the middle, remove spare to find it.
    Put a paper clip in the plug, from behind while plugged in the pump, so it made a better connection. Push the clip from behind.
    Now no problems
  • I'm no mechanic, but I hope this helps if u run into anymore problems. Along with my fuel pump(which if u havent checked ebay pretty reasonable) I had the ignition switch(modulator) changed. Did a little research online, found it to be common problem with these cars. Hope this helps.
  • Is replacing the fuel regulator on a 1999 blazer the same as on a 1997 or 1994?
  • kangfishkangfish Posts: 1
    where can I find a detail pic of one of these
  • duntovduntov Posts: 133
    Go to and navigate until you get a photograph of your part. Most of the 1985 through 1994 parts are different from the 1995 - up Blazer parts.

    You will need to know the manufacturer of the part and their part number. I use AC Delco parts when they are available and the website will sometimes give you a cross-reference from the aftermarket part to the original or replacement GM part number. Other brands may be cheaper and just as good as AC Delco or GM but I try to keep my Blazer "all GM", especially if it is a part that is visable to a critical eye. You can find parts cheaper that those sold by Rock Auto Parts. I only use their website when I want a photo of the part or a part number. Sometimes the photo may be a generic photo so don't consider the photo as as absolute.

    For example, the original GM EGR valve and a AC Delco replacement EGR valve for a 1991 S10 Blazer 4x4 4-door is black whereas most aftermarket brands are plated.
  • scrubsjimscrubsjim Posts: 2
    :mad: stupid dodge neon :confuse: fuel pump?? it starts after a few attempts
    somestimes idles ok sometime VERY rough, give it some gas it stalls then dies
    HELP PLEASE :lemon:
  • zac_a_takzac_a_tak Posts: 1
    My 95 Blazer will start just fine and after running for sometime she won't accept fuel and lose power under strain(like up hill).
    If she dies I just restart and she runs fine for awhile longer. I also believe that my fuel pump is singing way to loud. Like straining. Could this be a vent problem? It seems like once everything is heated up is when I have the problem. On cool days it just take longer for the problem to occur. I replaced the pump/filter and no gauage lights on the dash comes on. Nor does the check engine light come on and nothing ever shows up on the comptuer. I am lost for ideas and so are the mechs can you help? Zack
  • I had the same problem with my 97 blazer. It only did that when it was hot as well, now it won't even work. I was told it was the fuel pump. We just changed it, fuel filter and relay as well and the new pump wont even turn on........I'm stumped.......
  • I was driving down the interstate when the blazer just seemed to loose its power. I would give it gas but then seemed to act like it was getting too much. It eventually came to a stop. When starting off again it was fine for a couple miles and then just shut off completely. It would start up, but if i gave it any gas would quit. I was able to drive it home after it cooled just thought maybe got to hot. But a few days later it would do it more frequently until now. It is just parked. We replaced the fuel pump, filter and relay but the new pump won't even work. Battery is completely dead so have to charge it up....the new pump won't work........could this be a defective pump or is there something else causing this? :confuse: :sick: :cry:
  • duntovduntov Posts: 133
    The companies that make and sell electric in-tank fuel pumps recommend that you also replace the fuel pump wiring harness as well as the filter. Some companies even recommend cleaning the fuel tank or replacing it entirely with a new one. Something caused the fuel pump to fail! They do that in order to prevent customers from thinking the new fuel pumps are defective when they don't work.

    My late father built and raced jalopys from 1947 to 1952. He gave me some good advice on car repair jobs that are difficult to do. He said..."Replace the pilot bearing in the back of the crankshaft every time you can see it" That statment definately applies to a in-tank electric fuel pump, wiring harness and screen.l.
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