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Chevy Blazer Fuel Pump and Pressure Regulator Problems



  • dscattledscattle Posts: 1
    Ok i can only get it to start by jumping. i can get it to run by pouring gas down throttle body but dies when gas runs out. changed starter had coil and starter mod checked. replaced wires plugs, cap and button. also gas line filter. turns over great had battery checked also. volt meter in car shoes mid way between 9 and 14 when jumping car will start when volt meter reaches close to 14. rail pressure on prime pump is around 10 lbs, car running is around 40. also car will run after jumping for as long as you want (hours) as long as you dont shut off. it will restart if you do it within 1 or 2 minutes but no more. any thoughts would be great, thinking fuel pump but confused by rhe running after jumping
  • i have a 03 blazer, it starts showing 50 psi at fuel rail it runs great for about 30 minutes then starts spitting and sputtering and even acts like its running out of gas, i can press the acceleraator and no response some times, but it usually will pick up but it still sputters. at start up it shows 50 psi but when i let it sit and idle for about 20 minutes my fuel pressure drops to 14, i have changed the filter, is this a regulator problem or fuel pump?
    Thanks for any advise i get
  • freakistfreakist Posts: 4
    from my experience, it sounds like you have failing bearings in your fuel pump. to my knowledge, you would always get immediate response from your injectors, even if 1 or 2 were clogged or electrically intermittent, provided you can get pressurized fuel to them. Your fuel pump may be alright until it heats up enough to cause your bearings to run rough. this is almost certainly the case if you have driven the vehicle at a low fuel level for extended periods. the fuel pressure regulator is a relatively simple device compared to the pump, and if it were a heat issue in the regulator it would appear well before 20 minutes. the fuel in the tank acts as a coolant for the pump motor, thusly u get probs over time if u run with low fuel (below half tank). hope this serves!
  • ive got a 2000 chevy blazer, after car sits a few days, i have to prime injection with a cap full of fuel to get started, but it runs ok after i do this,what do i need to do to prevent this from happing again, getting tired of taking off air cleaner to prime with gas every few days

  • duntovduntov Posts: 133
    Replace the fuel pump relay and/or the fuel pressure regulator. Replace the relay first and if that does not fix the problem, replace the fuel pressure regulator.

    Fuel Pressure Relay: ACDelco D1786C (GM 19116657)
    $15.80 MSRP

    Fuel Pressure Regulator: ACDelco 21-72251 (GM 19106768)
    $126.00 MSRP
  • freakistfreakist Posts: 4
    edited September 2011
    Having a failing fuel pump is likely the cause of this, The pump is required to send fuel at around 58-62 psi (on mine) and when the engine isn't running, the battery must supply power to pump up this pressure, a worn set of bearings or anything else that causes the pump to be slightly harder than normal to turn will require more voltage than the battery can deliver at startup, especially since the battery must also send current to the voracious starter simultaneously, so the pressure from the pump doesnt get high enough to allow the system to effectively inject the fuel into the cylinders. u add gas, it fires it up, the alternator starts providing power at a higher voltage, the starter is turned off, shazzam, the pump is getting enough juice to work. A fresh battery may help for a little while,or even just jump starting), new pump is long term solution. A leaky fuel pressure regulator would likely not cause this issue, but will definitely ruin your mpg.
  • My 2000 Blazer has been not strating with out starting fluid for a few months (working long hours - no time to repair) and now it will not start. Will run if gas is soprayed into it. Fule pump runs - have nto check pressure but from all I see it seems to be the fuel pressure regultor.

    First am I right in my diagnosis and second - what is entalied in replacement. I find no clear instruction.

  • Did you ever figure this out???

    seem like the exactly problem i am having, once i get it started, it will restart with in a few minutes i let it set for over an hour.. no dice..

    was it the fuel pump?
  • Did you ever figure this out? sounds exactly like my issue
  • blazer wont start and fuel pump doesn't prime, is there anything that can stop this besides bad fuel pump or relay?
  • FIXED!! - I originally put a pressure gauge and it was reading 48lbs, i thought that was enough, however it was not.. I replaced the pump and the fuel filter and now i got 60 lbs (key on - not started) 54 lbs (running) Now it starts no issues.

    You should be near 61 lbs (key on - not started) for proper starting. 55 - 61 lbs for starting, the higher the better.

    A plugged fuel filter will cause the fuel pump to work harder and eventual damage it. Cheap and reasonable replaceable part.

    A fuel pressure tester is a easy way to figure out if your pump is working when key is turned on., I noticed the new pump has a new wiring design. They changed the way it connects because the connection were failing either shorting out or ground would break. So its a good idea to change it out if you have over 150,000 miles on it anyhow.
  • the wiring can be big issue, no grounding

    or shorting in the connection...
  • I had a circumstance once wherein I had a short inside the oil pressure sender, and this kept blowing the fuse on the ecm "b" bus, which killed the fuel pump relay. whatever you do, don't try putting in larger fuses to get it to run longer if you find the ecm fuses keep blowing. it may require pulling each sensor and bench testing it, but too many amps through the ecm sensor feed circuits will roast the ecm board, or set fire to wiring. newer vehicles with extra sensor stuff in the tank could be in severe danger if you attempt to put in a larger fuse when a circumstance like mine comes up. Luckily somebody got wise and stopped making the metal bodied senders, probably just because of the potential of underhood fires. careful work is in order when dealing with fuel tanks and lines, just sayin! Good skill to you!
  • after about 2 or 3 days it will start and run for about 5 minutes but then it cuts off and wont start again for 2 or 3 days, help?
  • i have a 94 blazer, ran great for a while, now it sputters and acts like its running out of gas, i know its none of the following: fuel pump, fuel filter, radiator, spark plugs.... all this has been chaged within the past week just as maint. but it still wont run... it throws out the right psi from the fuel pump but just acts like it isnt getting gas.. what could this be?!?! its driving me crazy!
    please help me !!!
  • darquedarque Posts: 1
    i replaced the fuel pump with aftermarket pump. it turned over, started and dies. sputters everytime. no fuel? im a amateur diy guy who just ordered a fuel pressure gauge, not here yet but i thought id write anyway my questions are kinda unique to the other 21 pages of detroit pump issues. prior to begin the fix, it used to run when primed dumping bit into inject, pep boys diagnosed bad fuel pump and it did not have any "obvious" other issues with fuel except for my car not starting ever unless fuel injector primed. fuel filter 1 year old as well. i also replaced the ignition module 9-12 months back.

    what i did.
    i got the tank out, and with a free junkyard aftermarket fuel pump (from a friend owns the junkyard w his promise he knew it worked [for how long is another story]) i busted the vapor valve on the tank and two of the three fuel line nipples on the old pump getting it out. so i have no idea what order these return to. + the pump had a different 4pin connector then the orig, so i had to splice the 4 wires into the new switch. grey,purple,2blacks*

    we replaced the pump with the junkyard one and went key on pump on makes sound turn over bamb starts up and dies everytime until the batt drained. if nothing else directly was problem prior to this the day before im concerned its only one of three things...

    1. junkyard part!!!!!. but the pump does work!!!
    2. fuel ~ possible reverse of the fuel lines. the new pump has 0 labels for the vent the out and the in. but the old one has vent in the middle f on the right (forward/fuel?) and r on the left (reverse/return) assuming i might have switched these i removed again and they seemed to only go on one way... the right one seems to be bigger so i assume its for getting the fuel to motor. that one fits perfectly on the new pump. the other two also seem to only fit back one way but idk? can they be on backwards?

    3. the electrical connection. spliced the 4 wires together with the new connector. 1)grey to grey 2)purple to purple and the 3&4) black wires. could i have made a mistake and reversed a ground to something else? i do get power when key on. is that enough indicator to my electrical being correct? could the pump in anyway run backwards? i really doubt it but idk? my assumption is the fuel lines backwards and or electrical backwards> ?

    so i do not know what else the pump needs to work if its humming? it does humm a lot longer than 5 -10 seconds once in a while... tank seemed clean inside as well. i assume the last thing i did is the first place to suspect but i am not eliminating other issues but i have huge gut feeling its something stupid...
    always is with me.

    i did notice the old pump had a oring on top of cap under connectors and nipples and i did not use that one on the new pump. is there a potential vacuum leak issue? i cant see honestly what the top oring could actually do if anything but prevent spillage. there is no openings and no vents it seems like an extra spare oring. any help would help but i dont have the right volt meter i only have amp meter and no pressure gauge yet. if someone could eliminate or confirm my gut feelings it would help narrow it down thanks.
  • I have 1999 Blazer 4.3L. We have replaced the fuel pump twice with different brands, 5 different pressure regulators, check the volume of the pump, checked wiring for voltage drop, replaced the spider, checked injectors for leak down, blown out and checked all fuel lines, checked the relay and wiring. All these checked out. We are unable to get the fuel pressure up to 60-66 psi required for the engine to run smooth on acceleration, engines idles fine. If we restrict the fuel return at the tank and raise the fuel rail psi up to 60-66 psi the engine runs great with no hesitation or back firing. Any more ideas of what it could be? :sick: :mad:
  • He said he replaced those... please read the OP before replying....
  • So, my 1998 Blazer (4WD, 2 dr) is having fuel pressure issues. Just turn the key, I get ~48-50 psi at the rail and it doesn't want to start with that. You do hear the fuel pump run for 2 sec.

    However, if I jump the car (attach a battery charger boost to the positive, negative grounded on the body) it jumps up to ~60 psi when the key is turned. Crank it and starts fine.

    Initially I believed the starting issues were either a low battery, old starter motor, or poor grounds. So, I just put in a nice strong CCA rated battery and starter motor. I also cleaned the grounds near the battery (found two there).

    So, my question is: do I need a new fuel pump, or is there a specific place in the electric system that I should check for poor grounds, etc.? Conversely, could I somehow can the circuit to runt the pump longer or at higher power?

    Thanks for any advice.
  • Clearly, these intense issue tell you that you just have another piece of junk.

    Mine runs fine right now, once it starts getting these issues, it is going to the junk yard. For the money you folks put in you can finance/lease or buy a better beater vehicle. So why bother? There are many more issues. To come!
  • did you ever figure out what was wrong with your fuel pump issue ? im having the same problem and put in a new fuel pump and its still not working... if you can help me out email me thank you.
  • I have a 2001 blazer that has similar issues. I had the fuel pump replaced about
    seven or eight months ago. Some mornings the car will crank over but will not start. Sometimes a cough or 2. I can wait 2 days and it cranks right up.Tried jumping it but extra juice had no effect.Driving it during the day when it only sits a few hours at a time no problems.Could my fuel pump have gone bad this quick.These were same symptoms before replacing fuel pump.

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