Chevy Silverado and GMC Sierra Fuel Pump/Fuel System

chuckh2chuckh2 Member Posts: 1
edited April 2019 in Chevrolet
hello everyone, I have an 88 gmc 1500 2wd with a 305 v8 and an auto trans. I think the electronic fuel pump circuit is possesed by the devil. My truck has been running fine until recently. Now it runs when it wants to. The fuel pump is less than a year old (napa brand), and the relay was the first thing I changed when all this started and the fuse is okay. Sometimes I have power going to the fuel pump, and sometimes not. Does anyone here know if there is some sort of collision safety cut-off switch, like on a ford? Is the computer somehow involved? If you can get it to start, it runs perfectly. Any help is greatly appreciated.
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Comments

  • jnealjneal Member Posts: 247
    I would tend to suspect a faulty connection in the fuel pump circuit.
  • fixruprfixrupr Member Posts: 2
    The sierra will die at stoplights, and it will die going around a corner sometimes, and may go a week without doing it. What is the problem?? Guess ??
  • mtlehnertmtlehnert Member Posts: 1
    Truck turns over but then dies. Has been running fine until now. Checked the fuel pump / replaced the fuel filter / distributor cap and rotor still won't start.
    Any ideas?
  • truitt83truitt83 Member Posts: 3
    I was planning on changing my fuel filter in my 01 silverado and I was wondering if there is anything special you have to do to change it. I have tried to loosen the bolts on either side of my filter but nothing. Is there a release or something that I am missisng. If anyone can help let me know.
  • truitt83truitt83 Member Posts: 3
  • ogsilveradoogsilverado Member Posts: 1
    my truck has run great up until now,ive changed all the important ignition parts,and the fuel injectors,it dogs when you barely crack the throttle and then catches and kind of takes off.i have no check engine lights on ,checked the smog lines.where to turn next?it feels like it running on 7 cylinders,but it feels like it could be starving for fuel,but it doesnt completely die,its driving me crazy!.can someone help!! :cry:
  • dptaylordptaylor Member Posts: 1
    Hi, this is my first time on a site like this, I'm a woman in Jamaica with a fabulous truck that myself and anybody else that rides in it or just sees it loves immediately.
    I do have a Large Problem with going through Fuel Pumps, as this is my 4th one for the year. One mechanic suggested using
    an external correct psi fuel pump like in the days of the
    Carberators. ??? What do you think.
    This is what has happened 4 times now.
    Please remember Jamaica does NOT have wonderful fuel. So
    maybe an additive could help, any suggestions would be
    appreciated.
    TRUCK WILL BEGIN TO HESITATE WHEN TAKING OFF, THEN THE
    CHECK ENGINE SOON LIGHT COMES ON, THEN ON THE SIDE OF THE
    MOUNTAIN OR ON A VERY SKINNY ROAD I FEEL MY TRUCK LOOSE POWER AND THE ENGINE STOPS AND ALL THE DASH LIGHTS COME ON,
    (THIS ALL HAPPENS IN A MATTER OF 10 MILES OF DRIVING)
    THEN I BEGIN TO PRAY AND TRY TO FIND A PLACE TO PULL OVER SO THE WILD DRIVERS DO NOT RUN INTO ME. MY PRAYERS HAVE BEEN ANSWERED AND I ROLL TO A SAFE PLACE. THEN THE EMBARASSMENT OF MY LOVELY TRUCK BEING TOWED TO THE LOCAL
    RACING SHOP. (I FIGURE THOSE GUYS ARE THE MOST UP TO DATE
    ON HOW TO FIX THINGS.)
    WHEN THEY GET THE FUEL PUMP OUT AND TAKE IT APART THE BRUSHES ARE ALWAYS DOWN TO NOTHING.
    WHEN FIXING WE
    1) REMOVE TANK AND CLEAN
    2) REPLACE THE PUMP
    3) REPLACE FUEL REGULATOR, UP ON THE ENGINE
    4) REPLACE ALL THE FILTERS.
    THIS MECHANIC FEELS I BURN THE PUMPS BECAUSE I RUN MY
    TRUCK ABOUT 18-20 HOURS A DAY WITH THE A/C ON FULL BLAST.
    I AM SOMETIMES AT A STAND STILL FOR OVER 30 MINS.
    ANY IDEAS OUT THERE?
    MANY THANKS
    DPTAYLOR :sick:
  • bcrawfordbcrawford Member Posts: 3
    i had a 92 that started with the same conditions... not long after it would idle fine but choke and die with any kind of acceleration. I fin ally took it in to the shop. after three days and lots of new parts(at their expense) it was a worn distributor bearing. i replaced the distributer assembly with a rebuilt, the truck never ran so good! 400000 km and still going strong!
  • ibnot4uibnot4u Member Posts: 3
    I have a 2000 chev silverado z71 with the 4.8 in it. about 6 mo ago, it starting becoming hard to start, like its out of fuel. After you crank it for about5-7 sec, it start and sputters then picks up. It then smells like it was flooded. (gave it no gas when turning the key) Starts perfect 1st thing in the morning but after the initial start, it acts up. My fuel mileage has gone down to 12 mpg. TERRIBLE! It even sounds like it misses every now & then while driving down the hiway. Fuel filter has been changed but no diff. I was told it could be the fuel pump having not enough pressure, the throttle sensor, or the fuel pressure regulator. HELP!! PLEASE!! :sick:
  • albird1albird1 Member Posts: 2
    My truck runs fine but every once in awhile I hear a buzzing sound like an electric motor noise from the back of the truck. I just had the dealer replace the fuel pump at 60K miles but it is still there. I only use the truck now for long road trips usurally towing so I really need it to be reliable. The fuel filter has been changed twice in the past 6 months as well. It does it when driving not idling between 25 and 45 mph as far as I can tell. I tape recorded it so I am even willing to send someone a cassette tape of the noise. Any suggestions would be appreciated.
  • milkermilker Member Posts: 3
    My '99 Sierra won't start with the first attempt. It starts just fine when you try again for the second time and runs just fine afterwards. Any guesses? Fuel filter? Fuel pump relay? Thanks!!
  • rortiz1242rortiz1242 Member Posts: 4
    When my truck began to not start on first crank my problem was a bad distributor. If you take it to a mechanic have them check that before they try to sell you a new timing chain. Talking from experience...

    Robert
  • rortiz1242rortiz1242 Member Posts: 4
    what would cause my fuel gauge needle to flutter like its vibrating. I had my truck worked on back in february and ever since it has been doing that. I am not happy with the mechanics who worked on my truck and do not want to take it back to their shop in Austin Tx
  • cole1976cole1976 Member Posts: 1
    Did you ever get this fixed? My 5.3 started acting like this too. Exactly the same thing. Starts great int he mornings, etc, but after sitting around it has a prolonged start.
  • ibnot4uibnot4u Member Posts: 3
    I am starting with the fuel pressure regulator which will be replaced this weekend. If that doesn't work, i will go onto replace the throttle position sensor, and last but not least, the fuel pump.
  • rortiz1242rortiz1242 Member Posts: 4
    in my instance it was the distributor. the mechanics shop sole me a timing chain then told me it was the distributor
    idiots. dont' go to klingemanns in austin tx
  • seewoodyseewoody Member Posts: 7
    Sounds familier. My "96" with 5L man. 4X4 ext.cab The throttle plate would stick at idle position-carbon in intake-around 90,000miles. Then service engine soon light around 100,000miles. Would come and go. then it wouldn't stay cleared 110,000miles.Started hard when hot, shook the clutch plate at idle to rattle, smelled like sulfur. Borrowed a friend's code reader, DTC-Rich right bank DTC-Rich left bank DTC-engine miss. dealer said fuel press.reg. was leaking into the intake plenum area. The injector/regulator assembly would need to be replaced with an updated version including a different mounting bracket plus the usual seals and o-rings. I said make it so. Well I bit the big one for $1,000.00. It was worth it. Ayers Chevy- Dover,NJ. Not the Jerk dealer who sold me the truck new. warnock.
  • mastercraftmastercraft Member Posts: 1
    I have a 2000 Silverado with the 4.8 and I have the EXACT same problem. Start's fine first time in the morning, then cranks for a few seconds before it barely turns over and then smells like gasoline. Mine also started about 6 months ago and since then have been getting terrible gas mileage. I have replaced the fuel filter and checked the fuel pressure regulator. Things I haven't done but have been suggested to me are; check the plugs, distributor, connections, fuel pump, diagnostics test at Chevy dealer... I am not sure where to start because many of them are expensive fixes. If anyone has had this problem and knows how to fix it let me know. :mad:
  • seannooseannoo Member Posts: 15
    My truck generally will not start on the first try. There used to be a buzzing sound that would last for about 3 seconds when I would turn the ignition on, but it no longer does that sound and I am sure the problems are linked. I think it is some type of fuel pump primer, or some type of solenoid valve, but I am convinced whatever that noise was, is the reason my truck is having problems. Does anyone know the source o my problems? Any help will be very much appreciated.
  • seannooseannoo Member Posts: 15
    Did you ever figure this out? It sounds like the same problem I am having; it runs fine once it gets started, but it usually won't start on the first try unless it has been run within the last hour or so. I think it is some type of cold start injector that is not functioning, but I don't know where to look.
  • jnealjneal Member Posts: 247
    The buzzing sound you used to hear was your fuel pump running. If you no longer hear it when turning the ignition key to "ON" position your pump is on the way out.
  • seannooseannoo Member Posts: 15
    I considered that, but it runs fine after it is started. the thing is that, previously, the pump would prime the system for a few seconds every time I turned the ignition, but now it never does. I think there has to be something to "tell" it to prime the system, that is no longer functioning. Does that sound likely? Do you know if that is possible?
  • jnealjneal Member Posts: 247
    The only thing else I can suggest is to have your fuel pressure and fuel pressure regulator checked.
  • scullerjayscullerjay Member Posts: 1
    I have the same problem lately. I noticed it about a week ago the needle flutters like it is vibrating. Sure would like to know what is going on.

    Jay
  • tbullingtontbullington Member Posts: 5
    I also have a 2000 Z71. My truck is doing the same thing. I had the fuel pump checked out. Local mechanic said that it was fine. Someone told me that it is the fuel pressure regulator. You can get it for about $45 at Autozone, but I havn't tried it yet. Have you found a solution to the problem yet? Please let me know what happens for you. This is a pain when it comes to fuel economy.
  • seannooseannoo Member Posts: 15
    I haven't fixed my truck yet, but plan on getting around to it this weekend. A friend of mine told me last week that he had the same problem on his truck and it was the fuel pump. Apparently there are 2 fuel pumps on our trucks and the one that is under the hood and pressurizes the system is not working. The main one in the back is still working, so the truck will run fine after the motor has started and fuel has started to flow. When I finally get around to fixing the problem, I will post what was wrong for sure.
  • tbullingtontbullington Member Posts: 5
    Thanks, Keep me posted on what you find out.
  • ibnot4uibnot4u Member Posts: 3
    OK,fixed my problem! It was my fuel pressure regulator. I also found out an easy way to check and see if it is bad. Pull the little hose off the top. If fuel comes out of the regulator, it's bad. Fuel should NOT come out this little spout. That is what is causing the "flooding". Good Luck!
  • tbullingtontbullington Member Posts: 5
    Great,
    I will go by one today and see if it fixes mine.
    Thanks for getting back to me.
  • bowtie6bowtie6 Member Posts: 2
    We have a 2005 Silverado, the check engine light keeps coming on. We took it to the dealer and after 2hrs. they said we needed the gas cap replaced. With in a month the light came on again, and they told us the same thing. Within a month of replacing that it happened a third time. They(the dealership) tells us we arent tightening the cap enough, that isnt true. Does anybody have any suggestions?
  • tbullingtontbullington Member Posts: 5
    fixed mine this weekend. I changed out the pressure regulator and it seems to be working right. $45 at autozone would have fixed my 6 month problem. It seems fine now.
  • 99transportonr99transportonr Member Posts: 5
    FUEL FILTERS.... FUEL FILTERS... FUEL FILTERS

    Changing your fuel filters regularly will save your fuel pump.
  • ksr3ksr3 Member Posts: 2
    I am hoping to get some feedback from those of you who have driven one of the new 2007 models with the new Active Fuel Management. This is where 4 of the 8 cylinders are deactivated when not needed, and per the articles is supposed to be "seamless".

    The Active Fuel Management is supposed to give you better gas mileage. Is there a tradeoff in performance? Is it really "seamless"? Any comments would be appreciated.

    Thanks.
  • edboggsedboggs Member Posts: 3
    They are using a faster CPU with more RAM and a ECMw/TCM instead of just a PCM. They use special lifters which are a lifter within a lifter and special cam lobes on the 4 cylinders that get deactivated when AFM is enabled. The special lifters keep the valves on those 4 cylinders closed when AFM is enabled by having the center portion of the lifter(part that pushes against the pushrod) bleed down when AFM is active. It is used on engines which have the drive by wire throttle body so the ECM is able to push the "gas pedal" down for you without your even knowing it to make AFM "appear" seamless. Of course there is no such thing as a "gas pedal" anymore, but for anyone unfamiliar with electronically controlled fuel injection and drive by wire it can still be called a "gas pedal" since those people don't know the difference anyway.
  • bobberinobobberino Member Posts: 4
    I am also wondering about this 5.3ltr motor with A.F.M. If it was just electronically con-trolled, I might not be so worried. But apparently, there are mechanics involved as well.
    For some reason, I am just worried this motor may develope more problems because of more moving parts/new tech. etc. I am not a gearhead, just looking to buy a new truck.
    ( Currently drive 1994 Silverado Ext. Cab 4.3 V6) I am thinking more about the 4.8ltr
    for the new one???? Any thoughts. Anyone? Anybody driving a 5.3ltr with A.F.M.??

    Bobberrino
  • edboggsedboggs Member Posts: 3
    The 4.8 doesn't have AFM. The 5.3 does and it is electrically controlled and mechanically activated. It is controlled by solenoids and pneumatically enables and disables the special lifters. That stuff can fail and if it does it will require a top end tear down which is costly and time consuming. The 6.0L V8 also has VVT which phases the camshaft timing. This is also done by the ECM so you're not supposed to know it is even happening. Another thing to break. I'm starting to like the Coates spherical rotary valves more and more.
  • 1offroader1offroader Member Posts: 208
    Wikipedia has a pretty good explanantion of AFM. Because AFM shuts off valve lifters to deactivate 4 cylinders it is extremely important to use the factory-recommended oil viscosity. If I recall correctly, the recommended viscosity for the 6.0L engine in the new Silverado is 5W-30 (you should verify this for yourself). I usually run 10W-40 in all my vehicles, but it looks like I'm going to have to make an exception to that rule.
  • bobberinobobberino Member Posts: 4
    I have also read this Wikipedia explanation of A.F.M. It does seem to me that it is possible for more problems down the road, hence my preference for the 4.8ltr engine.
    Also, I will be using my truck for light towing(boat) and loading gear. Thus, I think the
    time the 4 cyl. A.F.M. useage would be minimal. I doubt the truck would be using only 4 cyl. when towing anything.?? So I dont see what the real advantage would be in gas mileage when towing. If you drove it like a car unloaded,.....OK, maybe. Any thoughts??

    Bobberino
  • 1offroader1offroader Member Posts: 208
    I think the 4.8L is a bit light for towing. AFM doesn't sound that complex to me, and of course things of any sort can go wrong "in the future". If that is the only consideration we'd never try anything new. But, overall, for me the potential benefits outweigh the potential risks.

    When towing, my guess is that AFM would only kick in when coasting downhill. Unloaded, it probably would work a little more often - when coasting downhill certainly and possibly when cruising on a flat hwy.

    Re: the previous comment about VVT, I disagree. It is a proven technology and is being used on most engines nowadays. It's nothing to be afraid of. In fact, VVT is responsible for the great power and mileage numbers we are now beginning to take for granted.
  • jmackeyjmackey Member Posts: 4
  • jmackeyjmackey Member Posts: 4
    My 93 gmc had been sitting for 6 mo.the tank was drained by gas theives.added fuel,now gauge shows way past full & truck will only idle.can make it move by feathering throttle.adding carb clnr will make it run right.replaced fuel fiter,looking at pump.?gauge sit bothers me.any suggs?
  • liftedsierra00liftedsierra00 Member Posts: 1
    Is that what that is when My truck wont start? the engine cranks for a few seconds I wait and moment and the it fires up.? Also when I fill up my fuel needle goes wack. I know my tanks full but the needle shoots to empty and goes up slowly and back to empty. *SHRUGS* any ideas?
  • seannooseannoo Member Posts: 15
    I have been lagging on getting my truck fixed of this problem. Although I am not having the same issues as the other guys (using excessive fuel, etc.) since the fuel pressure regulator fixed their problem, I am going to change mine out too to see if that corrects it. I was at Pep Boys and they wanted a little over $90 for the regulator, so I am going to get it from Auto Zone where one of the guys said it was only $45. I will put it on my to do list for this weekend (for sure this time) and let you know if that fixes things.
    It sounds like you and I have the same issue, in that it won't start the first time unless you crank it for a long time, but once it is running, it is fine.
  • litalow79litalow79 Member Posts: 10
    My fuel pump stays ON after the truck has been shut off... often runs the battery down if I dont disconnect it at night. has new fuel pump in the tank and a new switch thing,(like a timer switch)... we have checked out many electrical scenarios, just cant figure this one out! Please help! thank you
  • seannooseannoo Member Posts: 15
    It sounds like you have an electrical short somewhere. The fuel pump should only run when the ignition is on and the fact that yours is running when the ignition is off is very strange. Does anything else stay on that should not be when the ignition is turned off? Did the problem start around the same time that you had something added to the electrical system? It could also be a bad fuel pump relay in your electrical panel under the hood. The contacts on it could be internally shorting out and causing it to stay on.
  • litalow79litalow79 Member Posts: 10
    Hello Sean,
    do you think that a truck like mine would have a timer on the fuel pump that stays on for 20 seconds after the truck is shut off? thats what my mechanic changed out last time he worked on it... I really have never heard of such a thing, but also, do you think that this timer and the relay might be the same thing? I hate my truck... but we just put a new motor in it, it didnt have this problem before, just the gas guage didnt work, this fuel pump thing started after we got the gas guage fixed.
  • seannooseannoo Member Posts: 15
    litalow; I don't know what would be the purpose of a timer that would keep the fuel pump on after you turn off the ignition; it just doesn't make sense to me. when they fixed the gas guage, did they replace the sending unit or have to drop the tank for the repair? If so, your problem probably lies in the back of the truck in the area of the tank; at least that would be my guess.
  • litalow79litalow79 Member Posts: 10
    Hi Sean,
    It sure was nice of you to help me with my truck dilemma... The truck went back into the shop again last week, and I hope that we will finally get all the bugs worked out eventually. believe it or not your comments really helped me to persuade my mechanic to look at that relay one more time... they told me that the relay was the first thing they changed out, but after I had them check it again they said that when they pulled it out, that it had rattling parts inside it and they were able to get another replacement one at no charge to me. I havent gotten it back yet because the other thing they needed to change out was a bad pilot bearing, (clutch)..... it was ready today but they didn't have time to test drive it yet so I should have it in the afternoon sometime tomarrow. thank you so much for your help, and good luck to you with your projects always! R.R.
  • dagolferdagolfer Member Posts: 8
    I have 2,000 miles on a new 07 Silverado 5.3 with Active fuel management. It is incredibly seamless. If I did not have the on board computer showing the instant fuel economy, I would not know when it was activated. The fuel economy, however, is not good. Driving many highway miles in cruise control, no rush hour traffic and not pulling anything, my average fuel economy is 14.5 MPG.
  • 81ringer81ringer Member Posts: 2
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