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Chevy Blazer Fuel Pump and Pressure Regulator Problems

135

Comments

  • vbspeedovbspeedo Member Posts: 1
    I'm having the same problem, and a friend of mines said it may be the pickup coil. the pickup coil sends a signal to the injectors to spray the fuel into the engine. So I'm going to change mines in the morning and I'll let you know if that works. pickup coil cost between $12 and $15.

    vbspeedo
  • jlflemmonsjlflemmons Member Posts: 2,242
    I hate to disagree with your mechanic, but every tank mounted AC Delco fuel pump makes a buzzing noise during prime. You cannot put a motor/pump (fuel pump) in a great big hollow drum (fuel tank) without getting some noise. I have been working on GM since before they started using electric fuel pumps, and the pump ALWAYS makes noise during the prime cycle. They still make noise when the car is running, but you cannot hear it over the engine. I'm not talking about a loud buzzing, but with half-way decent hearing you can tell when the pump primes.
  • jlflemmonsjlflemmons Member Posts: 2,242
    Not sure what "pickup coil" he means, unless the crankshaft position sensor. This is mounted down near the harmonic balancer and detects that the crank is turning. If it fails, it will tell the ECM that the engine is not turning, and the ECM will in turn shut down the fuel pump and injectors.
  • pops1956pops1956 Member Posts: 1
    my wifes 2000 blazer had check engine light on. they did some kind of giagnostic on it and said it was a fuel system problem.it was running ok at the time and since they didnt seem to know what the issue was she just ran it. well today it wont start. just turns over .fuel pressure comes up normally at prime but wont hold,drops straight to zero. how do i distinguish between the pump, regulator or something else? thanks.
  • goodie2goodie2 Member Posts: 3
    check the pickup coil, at bottom of distrubtor
  • jlflemmonsjlflemmons Member Posts: 2,242
    Also, make sure the connector hasn't come off the crankshaft position sensor. looking from the front, it is at 7 o'clock on the crankshaft. If the sensor is not telling the ECM that the engine is turning, the engine will not start. I am not sure which it shuts down, the ignition, the fuel injection, or both.
  • blazzr2blazzr2 Member Posts: 1
    Ok, had a check engine light a couple weeks ago...came back saying cam and/or crank sensor faulty, engine misfire, blah blah blah...(probably my own fault for driving w/ a flat spot on a tire--too much bouncing).
    It would be on for a couple days, then go away for a few more (this has been going on for a few weeks now).
    Now, today, pulled into the driveway (kinda gunned it to pull up the drive way--just screwin around with my truck), and it would not start again. No distinct whine from the fuel pump, no nothing.
    The only reason I'm posting something here instead of replacing the sensor is to see if there's a common problem with blazers....
    Mine is a 2000 Zr2, and has had a bit of an issue with a quick goose of the accelerator right before shutting the vehicle down. This is the third time it has happened (and yes, I've learned my lesson about hittin the gas right before I turn it off), but this is the first time I have not heard the fuel pump engage. The fuel pump is just over a year old (and I will NOT do that job again), and previously with persistence it would be up and running again. Any ideas/feedback?
  • jlflemmonsjlflemmons Member Posts: 2,242
    No laughing allowed, but kick the bottom of the fuel tank in the area where the fuel pump resides. Don't go for a 50 yard field goal here, just a good solid thump.

    Then see if the fuel pump primes up.

    I really cannot think of a reason why gunning it before shut down would keep it from starting. It might make it turn over a few extra turns to clear the excess fuel, if any, but the ignition should be generating more than enough spark to overcome the small amount of extra fuel left.
  • blazerownerblazerowner Member Posts: 1
    I have a 94 blazer, The fuel pump went out! Fried the wires in the tank! Replaced entire assy. pump works! Got fuel to the test port, havent checked psi as of yet! Replaced the cpi (SPIDER) still no fuel at injectors!!As long as i feed it fuel by hand it runs! The cpi is not working. What controls it! The Crankshaft sensor!! Located bottom leftside of Timing Gear cover!! Aah hah!!! MINE dont have one at least not there! The haynes book clearly shows one but not on my Blazer s-10 4.3 V-6 vortec 4x4 vin 8th w 4 door been in family since day 1 ANY IDEAS outthere
    i even bought the sensor just to see what it looks like
  • jlflemmonsjlflemmons Member Posts: 2,242
    If yours is a late 93, it may not have the crank position sensor. What Haynes is showing is correct, the CPS is bolted up at the 7 o'clock position relative to the crankshaft pulley.

    If your oil pressure sending unit is not registering, the fuel pump will prime, but not run. Safety feature to protect the engine in event of oil pressure loss.
  • bluejay5bluejay5 Member Posts: 3
    Have a 97 blazer with fuel pressure problems. Pressure at the fuel rail about 7lb and falls to 0 as soon as pump stops, took the line off at the output of the filter and can NOT hold the pressure back with my finger so i figure the regulator is bad. I also have a 95 that I replaced the regulator assy. about 7 months before the tranny took a powder at 180K. Since both are engine code W shouldn't I be able to use the one use the one from the 95 and put it in the 97? Just trying to save some cash in these times.
    TIA
  • jlflemmonsjlflemmons Member Posts: 2,242
    Easy way to check, go to an online parts store (Autozone, Advance, O'Reilly) and look up the regulator for both year models. Chances are it will be the same part number for both.
  • whitemfoxwhitemfox Member Posts: 6
    I have a 96 Blazer w/v6 vortez, I have been having trouble with it starting, I need to prime it to get to start then it seem to run ok although it reves a littel high when drving. but because of that I have changed the fuel filter several times because when I take it off the gasoline looks blackish and tarry looking and I cannot figure out why any suggestions :confuse: The fuel pump pressure is a little of 50 psi
  • marblazemarblaze Member Posts: 16
    CHECK YOUR FUEL PUMP RELAY IN THE FUSE BOX UNDER THE HOOD IT WILL BE LABELED
  • marblazemarblaze Member Posts: 16
    IT DOES NOT SOUND LIKE PRESURRE REGULATOR IT SOUNDS MORE LIKE CHECK VALVE IN YOUR FUEL PUMP OR THE CARBON FIBER LINE THAT IS IN THE TANK THEY ROT I HAVE SEEN THIS HAPPEN ALSO YOU COULD HAVE A SPIDER JET LEAKAGE I HAVE ALSO SEEN THIS AND IT IS HARD TO PIN POINT IT , ITS REALLY JUST A GUESSING GAME AS WHERE TO START.
  • stealthnystealthny Member Posts: 25
    I have a 1007 blazer 2dr.
    Every morning I have to wait and turn it over 4 to 7 times to build enough pressure to start it. A mech looked at it and said there is a check valve in the fuel pump that is not holding the pressure in the line over night and I should replace the fuel pump. My question is when I look in the floor of the rear compartment there are 4 lg screws in the floor for tie downs. I am not sure if I remove the cover if there id an access panel to get at the top of the tank. Does anyone know this? or does the tank have to be removed to replace this pump.
  • jlflemmonsjlflemmons Member Posts: 2,242
    Okay, first off, no, the four tie downs will not give you access. Second, the pump should go through a "prime" cycle when you turn the key to the on position before cranking the engine. You should be able to hear this if you have someone turn the key from "off" to "on". The pump will make a hum/buzz sound for a few seconds. That is when it preassurizes/primes the system. If you are not hearing that sound, but the engine runs fine once started, you do not necessarily have a bad fuel pump. The power for "priming" the pump comes through a different circuit than the "run" power.

    Did the mechanic check the pressure in the fuel line to confirm that the line does indeed pressure up when the engine is running? One other issue that causes the symptoms you describe is a leaking fuel regulator or spider assembly in the manifold. In this case, you actually have excess fuel that has leaked into the intake and "flooded" the engine. Cranking will clear this fuel and allow the engine to start. It will usually only do this when the car has been sitting over night. If you start the car and drive it several times during the day, the leakdown will not be enough to notice when you start the engine. It will just run rich for a few seconds until the excess fuel is burned off.

    I mention the other issues because changing the fuel pump is expensive, both in parts and labor.

    And I will assume in your title that you have a 1997 Blazer? :P
  • stealthnystealthny Member Posts: 25
    RE 1997 blazer.

    OK he thought like you it may be fuel leaking thru the night into the cyl. I believe this is the first thing he checked. He did change the plugs rotor and cap stating that they were very old but never mentioned the cyl being fouled by excess gas.He said that when he pressure tested the gas line it did have enough pressure but when the truck was off it lost that pressure. His explanation was the fuel pump. If I turn it over I can hear the pump. I have to turn it over quickley about 4 to 7 times then she fires up and runs fine. It seems to be getting worse as now I amy have to use this proceedure even after a half hour of the truck being off. Please advise

    Thank You

    Steve
  • jlflemmonsjlflemmons Member Posts: 2,242
    Did the mechanic mention how much pressure the pump was putting out? I am thinking it should be more than 65psi.
  • stealthnystealthny Member Posts: 25
    No he didnt tell me that. however after the truck sits for 4 or 5 days it still has the same problem. If the GPV was leaking thru overnight wouldnt that dry up overtime. Again he looked at the plugs and there was no exsessive Gas on them. Also I am still not clear on this pump deal. Is there a way that the gas line should pressure that could fail and let the gas in the line leak back into the tank causing low pressure in the line?
  • whitemfoxwhitemfox Member Posts: 6
    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.
  • stealthnystealthny Member Posts: 25
    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 Member 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.
  • stealthnystealthny Member Posts: 25
    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

    Thanks
    Steve
  • ixxixxiixxixxi Member Posts: 9
    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?
  • stealthnystealthny Member Posts: 25
    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?

    Thanks
    Steve
  • whitemfoxwhitemfox Member Posts: 6
    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 :(
  • stealthnystealthny Member Posts: 25
    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 Member 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. :)
  • stealthnystealthny Member Posts: 25
    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

    Steve
  • stealthnystealthny Member Posts: 25
    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.

    Thanks

    Steve
  • jlflemmonsjlflemmons Member 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.
  • stealthnystealthny Member Posts: 25
    ok Thank You
  • whitemfoxwhitemfox Member Posts: 6
    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 Member 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.
  • stealthnystealthny Member Posts: 25
    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 ...no 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.
  • whitemfoxwhitemfox Member Posts: 6
    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.
  • stealthnystealthny Member Posts: 25
    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
  • ixxixxiixxixxi Member Posts: 9
    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?
  • stealthnystealthny Member Posts: 25
    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?
  • dalanhamdalanham Member Posts: 1
    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 Member 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.
  • bryonmaxbryonmax Member Posts: 1
    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 months.now 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 Member 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 StarTech.com 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. ..
  • danlucentedanlucente Member Posts: 2
  • mouthsmom63mouthsmom63 Member Posts: 1
  • wominal38wominal38 Member Posts: 1
    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 Member Posts: 2
    Hi,

    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.

    Thanks
  • mntnresqmntnresq Member 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 Member 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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