GM Inside - Ford Inside - Ford Ranger - Jeep - American Muscle

Support FSC and see no ads! - Click Here
Page 1 of 2 12 LastLast
Results 1 to 20 of 23

'99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

This is a discussion on '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown within the Technical / Maintenance forums, part of the General Discussion category; (Please note: I initially began inquiring about this problem in the thread "Knowledge Desperately Needed", but felt that some background/pertinent ...

  1. #1
    Registered User
    Join Date
    Jun 2011
    Location
    East Tennessee
    Posts
    11

    '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown


    Support FSC and see no ads! - Click Here
    (Please note: I initially began inquiring about this problem in the thread "Knowledge Desperately Needed", but felt that some background/pertinent info may help you to understand my problem a little clearer.)

    We obtained this Suburban from a local dealer in an even/lateral trade for an older pickup truck. He'd taken it in on trade, and only traded with us in order to help our family out. He didn't know anything about this vehicle, didn't make any promises, and I accepted it fully with the knowledge that it was "as-is, history unknown". (Not that it matters, but it's 4x4 automatic)

    What we knew about it at the time of acquisition: Had/has a preexisting noise in the engine that sounds to me like a "valve tap", but the dealer was concerned that it was a rod instead of a valve. Desperately needing a vehicle capable enough of hauling around our tribe of 9, we accepted the risk that it might have a rod knocking, and went with it. We bought the 'tank' at 99,XXX miles, and it presently has 135XXX miles, "tap" still existing, but not of major concern to us at the present time. (Have used 50% oil, 50% pure synthetic since acquisition in case it was a rod, but have had no problems at all with the engine itself, outside of fuel issue addressed below.)

    I am, at best, a "shade-tree mechanic" with extremely limited knowledge of newer vehicles. I can work on the old early 70's vehicles with no problem, and can delve into the inner workings of an engine with no qualms at all - but you get me past the old carburetors an into anything that has even the remotest of rumor regarding fuel injection, and I am lost and thrown to the wolves.

    Last summer, while in central Ga, the tank left my wife sitting in the middle of the road. (I was back at home in the mtns of East Tn) Symptoms: No fuel getting to the carburetor - she had to have it towed. The Ga mechanic said that there were "issues" with the wiring harness, allegedly "rewired" the harness to make the fuel system operable once again, charged her $400+/- and sent her on her merry way. (Upon her return home, I saw zero evidence that any "rewiring" had taken place, but happy to have wife, "tribe", and our family tank back home, I complained not once.)

    Present Day: Around 2-3 months ago, I pulled into my yard in order to load up some chains (oldest son had his truck stuck and needed recovery). I turned off the tank, obtained what I needed (plus a "quick" visit to raid the kitchen) and re-entered the vehicle.

    Attempted to start, cranked enough times where I was afraid I was gonna burn up the starter, but nothing happened. In spite of the fact that my ears told me that the fuel pump was in fine working order, I decided "it must not be getting enough fuel pressure", so it was decided that the pump would be replaced. Out of necessity (never having enough money) more than anything else, I had to make the repairs myself, which you will discover is no easy task, especially for me. (I am also handicapped/disabled.)

    Almost 3 months and 2 new fuel pumps later, it's doing more than it has since I switched it off that fateful night, but it still isn't cranking. You can turn it over, and it "almost" starts, but cycles through all over again like it isn't getting enough fuel.

    What I've done (most recently): Removed the fuel tank (3rd time) to drain and clean; disconnected fuel lines from tank, filter, and intake - blew out with compressed air to rule out trash/water in the lines; new filter installed, reattached lines, reinstalled tank, attempted to start - nothing... Bled the fuel line in order to remove any air that may have been in fuel line - still nothing... Fires, tries to start, but just can't quite seem to make it. I have not yet checked the fuel pressure, but with a new pump, clear lines, and new filter, I tend to shy away from thinking that the issue is pressure related.

    With this being the second time this vehicle has given us problems with fuel abandonment, I am now pondering (openly) if the problem might lie with the fuel injection system.. I've read (numerous places throughout the 'net) about Vortec engines (from the factory) giving owners problems with the fuel injectors.. Since I don't know the history of this vehicle, it is unknown if this problem had been addressed prior to the previous owner's trade-in (he was allegedly the original owner).

    If the general consensus that it's fuel injection-related, what (if anything) can I do shy of replacing the whole fuel injection system that may get me back up and running again? Quite frankly, I don't have the $300+ to fork over to the parts supplier in order to obtain the replacement system...

    Help?? (I'm pretty desperate over here)

  2. #2
    Registered User
    Join Date
    Jun 2011
    Location
    East Tennessee
    Posts
    11

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    P.S.
    I should also note, when I say "It tries to start", I mean that when the starter turns over, the engine actually "runs" enough to where it "helps" the starter, but just isn't quite getting there. Fires great - seems to "want" to start, but then acts like it's not getting any fuel at all and starts over at square one. So, I may not know fuel injection systems at all, but what I'm hearing is telling me that some (very limited) fuel is making its' way into the cylinders, because of what I (allegedly) "know"....

    Again, "Help?? (I'm pretty desperate over here)"

  3. #3
    Registered User
    Join Date
    Dec 2004
    Location
    Earth
    Posts
    467

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    You really need a fuel pressure test gauge.

    Not very expensive and definitely required to diagnose a fuel problem correctly on a 99 5.7.

    Last edited by mattillac; 06-10-2011 at 02:42 AM.

  4. #4
    Registered User tricky01's Avatar
    Join Date
    Jun 2010
    Location
    CHI-TOWN
    Age
    43
    Posts
    195

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Sounds like trouble I was having, I changed fuel injectors and still gotten no start, fuel pump was less than two years old and had that changed with warranty at dealer again and still would be sluggish and hard starts to no start at times, also I changed coil, crank sensor, ing mod, fuel filter and still no start. Next I changed plugs, wires cap and rotor with all AC Delco parts and she fired right up. Some say it was the wires and some say cap and rotor but I changed them all. Wires list for $157 locally here but found them on ebay for $57 and Advance Auto for plugs cap and rotor. Advance Auto has discount codes online where you can get 40% off with free shipping, need help finding good parts at cheap prices just hit me up and I will try to locate them for you just have to wait for shipping but save $$$. But like mattillac also stated check fuel presure first.
    Last edited by tricky01; 06-10-2011 at 04:18 AM.
    "Pretty women make us buy beer. Ugly women make us drink beer." Al Bundy




    2000 Chevy "MYHOE" 5.7

  5. #5
    Home of the Snooki punch! CKTA's Avatar
    Join Date
    Aug 2001
    Location
    New Jersey
    Age
    39
    Posts
    54,498

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Sounds to me like the Fuel Pressure regulator is bad. Does it tend to not start after it's warm?
    2014 Carlisle All Truck Nats info..
    http://www.fullsizechevy.com/forum/o...g-1st-3rd.html


  6. #6
    loose nut behind da wheel JeremyB's Avatar
    Join Date
    Jun 2002
    Location
    Wisconsin
    Posts
    1,496

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Quote Originally Posted by Tes2fy View Post
    P.S.
    I should also note, when I say "It tries to start", I mean that when the starter turns over, the engine actually "runs" enough to where it "helps" the starter, but just isn't quite getting there. Fires great - seems to "want" to start, but then acts like it's not getting any fuel at all and starts over at square one. So, I may not know fuel injection systems at all, but what I'm hearing is telling me that some (very limited) fuel is making its' way into the cylinders, because of what I (allegedly) "know"....

    Again, "Help?? (I'm pretty desperate over here)"
    Pour a little fuel into the intake to see if it will start, if it doesn't help, then it probably needs cap and rotor

  7. #7
    Registered User Monstar_est87's Avatar
    Join Date
    May 2011
    Location
    City of Angels
    Posts
    67

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Yea Id say once you rule out the fuel pressure, check the injection system, o2 sensors, any possible leaks,.. O and fuses... As dumb as it sounds I believe that there is a fuse for the fuel pump...

  8. #8
    Registered User
    Join Date
    Jun 2011
    Location
    East Tennessee
    Posts
    11

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Has new cap/rotor; Wires/plugs; New fuel pump relay -- All were done in order to rule out potential problems preventing startup. I'm about ready to cut my losses, push it out to the road and stick a for sale sign on it. I sure am wishing I had never gotten rid of that trusty old pickup truck that I traded - at least it ran.

  9. #9
    Registered User
    Join Date
    Sep 2009
    Location
    Maine
    Posts
    1,737

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Very likely culprit here is the Crank Position Sensor (CKP). It will cause a no start like you describe, no fuel and no start. If you have a VOM and Haynes/Chilton manual the test procedure is simple and well explained in the manual.

  10. #10
    Registered User
    Join Date
    Jun 2009
    Location
    Sun Prairie, WI
    Posts
    67

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    If you don't have a VOM, you can get one that will get the job done for less than $10.00 at Harbor Freight. (Which can be ordered on-line if they're not local to you.) Good luck!

  11. #11
    Registered User
    Join Date
    Jun 2011
    Location
    Marana, AZ
    Posts
    8

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    I have the same issue recently with my 97 GMC 5.7L K1500. I have a full tank of gas and the truck will run when gas is poured into the throttle body. I replaced the fuel pump and filter approximately 7 months ago and replaced the filter again 1 month ago About 5 months ago I also changed dist./rotor caps, spark plugs and wires. When I turn the ignition key on the pump comes on for about 100-15 seconds then shuts off. While cranking the pump runs and shuts off a few seconds after the key is released. I did check and am getting fuel up to the pressure gauge fitting behind the intake. With key on and the schrader type valve core depressed the pump doesnt re-start and pressure is lost but only air comes out. with the valve dpressed and cranking the gas does squirt out the valve. Is it possible the pump could have gone bad? I am in the process of tryng to get a hold of a pressure gauge to check the fuel pressure but am not quite sure as to the procedure or what the pressure should be. Hope to have been specific enough. I appreciate any help you all could give me. Thank you.

  12. #12
    Registered User
    Join Date
    Jun 2011
    Location
    East Tennessee
    Posts
    11

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Update: I just now poured gas directly into the carburetor and it will NOT start. So, at this point, I'm as clueless as I was when it first refused to crank 3 months ago. It is firing, because it's "almost starting" as described in my original post above - but still refuses to crank. Geez, this is so dumbfounding.

    Ideas???
    Last edited by Tes2fy; 06-11-2011 at 10:18 AM.

  13. #13
    Registered User
    Join Date
    Jun 2011
    Location
    East Tennessee
    Posts
    11

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    06/11/2011 - Replaced the crankshaft position sensor ($68.99 + tax) - did not remedy the problem.

  14. #14
    Registered User tricky01's Avatar
    Join Date
    Jun 2010
    Location
    CHI-TOWN
    Age
    43
    Posts
    195

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Quote Originally Posted by Tes2fy View Post
    06/11/2011 - Replaced the crankshaft position sensor ($68.99 + tax) - did not remedy the problem.
    Take Coil and Ing mod in for a test. Some auto stores can test them. I was told if the Ing Mod has color on the dot on it that it is bad. But before you spend more $$ on parts not needed now buy fuel presure gauge or borrow one, they may even rent them, not sure but won't hurt to ask. Or buy test it and return it.
    "Pretty women make us buy beer. Ugly women make us drink beer." Al Bundy




    2000 Chevy "MYHOE" 5.7

  15. #15
    Registered User
    Join Date
    Oct 2010
    Location
    Savannah
    Posts
    53

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Quote Originally Posted by Tes2fy View Post
    Update: I just now poured gas directly into the carburetor and it will NOT start. So, at this point, I'm as clueless as I was when it first refused to crank 3 months ago. It is firing, because it's "almost starting" as described in my original post above - but still refuses to crank. Geez, this is so dumbfounding.

    Ideas???
    Have you looked at the cap and rotor?

  16. #16
    Registered User
    Join Date
    Jun 2011
    Location
    East Tennessee
    Posts
    11

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Apologies for the extended lapse since I last posted anything.

    We got it running, but the motor shakes/misses as though it has a combination of epilepsy and parkinson's. It wasn't running good, but good enough for me to drive it over the mountain into the largest town nearest me. I took it to Advanced so I could find out what codes were being thrown hither and yon: Ended up replacing both O2 sensors at considerable cost. It remedied the problem of the vehicle not "surging" forward as quickly as you'd expect when whomping down on the accelerator. In fact, it acted more as if it had a Geo 3 cylinder under the hood instead of a V-8. It now responds as expected, but still has a terrible-awful shake/miss to the engine. If you're moving down the road, it's not fine, but is usable. However, if you have to come to a complete stop, it has to be moved to neutral, or the engine is gonna die. You put it in neutral, it'll idle - but you put it into any moving gear, and it's gonna die. A stopped up cat has been ruled out, but at this point, I am as equally flabbergasted as I was when it wasn't running a'tall. It sounds exactly like it has something in the exhaust system that's stopping it up and preventing the engine from being able to "breathe"... That probably sounded weird, but it does sound like something is choking it and restricting the engine from doing what it wants to do... It sounds like it wants to surge and break free, but something is in there holding it back. Advance hooked up the code reader again after I installed the sensors and drove it a few blocks. The sensor problem was remedied, but it popped up 2 problems with "No DTCs" - meaning no codes, but indicative of a problem. One of their employees who's allegedly 'the most knowledgeable" (that was a very scary thought - he looked totally incapable of flipping a burger, much less diagnosing an unidentified problem) said it was almost assuredly a vacuum issue - loose hose or a hose with hole. I hold no stock in what he said, but still am grasping at straws trying to figure out what to do..

    Ideas?

  17. #17
    I drive buses. 97vortec383's Avatar
    Join Date
    Dec 2008
    Location
    College Station, Texas
    Age
    22
    Posts
    210

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Vacuum leaks can cause terrible misses in the engine. Could certainly be the problem but not necessarily the only thing that could cause it to miss.
    At my shop we use a smoke machine, find a hose (easiest one runs comes right out of the drivers side valve cover) and shove the end of the smoke machine in it. You also have to cap off the throttle body to keep smoke from making an easy escape but if there are any leaks they will be shown by the smoke coming out.
    You probably don't have a smoke machine but just an idea. Hopefully it can help in some way.
    1997 383 4x4 - Toy
    1998 Tahoe 2wd - DD

  18. #18
    Registered User
    Join Date
    Jun 2011
    Location
    Marana, AZ
    Posts
    8

    Post Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    Quote Originally Posted by Tes2fy View Post
    Apologies for the extended lapse since I last posted anything.

    We got it running, but the motor shakes/misses as though it has a combination of epilepsy and parkinson's. It wasn't running good, but good enough for me to drive it over the mountain into the largest town nearest me. I took it to Advanced so I could find out what codes were being thrown hither and yon: Ended up replacing both O2 sensors at considerable cost. It remedied the problem of the vehicle not "surging" forward as quickly as you'd expect when whomping down on the accelerator. In fact, it acted more as if it had a Geo 3 cylinder under the hood instead of a V-8. It now responds as expected, but still has a terrible-awful shake/miss to the engine. If you're moving down the road, it's not fine, but is usable. However, if you have to come to a complete stop, it has to be moved to neutral, or the engine is gonna die. You put it in neutral, it'll idle - but you put it into any moving gear, and it's gonna die. A stopped up cat has been ruled out, but at this point, I am as equally flabbergasted as I was when it wasn't running a'tall. It sounds exactly like it has something in the exhaust system that's stopping it up and preventing the engine from being able to "breathe"... That probably sounded weird, but it does sound like something is choking it and restricting the engine from doing what it wants to do... It sounds like it wants to surge and break free, but something is in there holding it back. Advance hooked up the code reader again after I installed the sensors and drove it a few blocks. The sensor problem was remedied, but it popped up 2 problems with "No DTCs" - meaning no codes, but indicative of a problem. One of their employees who's allegedly 'the most knowledgeable" (that was a very scary thought - he looked totally incapable of flipping a burger, much less diagnosing an unidentified problem) said it was almost assuredly a vacuum issue - loose hose or a hose with hole. I hold no stock in what he said, but still am grasping at straws trying to figure out what to do..

    Ideas?
    -I had similar rough idling conditions in both a 96 blazer and a 97 Tahoe that turned out to be the brake booster. You can experiment by pinching off or removing and pluggin the vacuum line that runs to the booster then start your ride and put it in gear while holding the brake and see if it makes a difference in how it runs. If so, you should replace the booster. Both my vehicles ran fine afterwards. Good Luck.
    Anthony G.

  19. #19
    Registered User
    Join Date
    Jul 2010
    Location
    Cleveland
    Posts
    44

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    I have zero vortec experience here, so this is out on a limb. I assume the Vortec motors have an EGR valve. If it's stuck open it would cause a serious vacuum leak, although you'd think the pintle position being off would throw a code.

    Good luck, real stumper there.

  20. #20
    Hayseed, Redneck yep BURBAN GUY's Avatar
    Join Date
    Nov 2010
    Location
    Nebraska
    Posts
    29

    Re: '99 GMC Suburban 5.7 Vortec - Fuel Problems - Remedy unknown

    There is also the fuel spider under the upper plastic intake, these can cause all kinds of funky probs.
    1999 Chevy Sub 3/4 ton 4wd
    True duals, Big O A/T 285's

 

 
Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •