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1989 Suburban V1500 TBI 350 problems...

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  • 1989 Suburban V1500 TBI 350 problems...

    Hey guys!

    I have an 89 burban that is giving me fits! I gave it a full tune up (cap, rotor, plugs, wires) new coil, ignition module, fuel pump and filter, IAC, MAP and still have a miss at idle when warm, and it bogs and backfires out the exhaust at takeoff and while cruizing. I have also replaced the exhaust, including the cat (needed it badly anyways) and also the O2 and the ECU temp sensor. I replaced the fuel pump because it just wouldn't start. That fixed the starting issue instantly, and ran better, but still not quite right.

    Im about to drive the thing off a cliff. Could the pick-up coil cause these issues? I have cleaned out the EGR Valve, I haven't checked the timing yet, but before everything went to hell, it ran perfect. Sometimes it will run great with no problems, but most of the time, it runs like dog doo. It will idle fine until it is at operating temp, then it will start an occasional miss, then get worse until it about kills itself. Stop lights I have to put it in neutral to keep it running when its warm, and it backfires while giving it gas off the line. At WOT is is just fine, the miss and backfiring go away.....

    Any suggestions?? I have scoured the internet for help with no luck. Thanks!
    Ryan
    2000 Chevy Silverado K2500 6.0
    1999 Chevy Suburban K1500
    1979 Chevy Silverado K10 454 4x4

  • #2
    Re: 1989 Suburban V1500 TBI 350 problems...

    Well, I have an 87 with similar problems. This weekend I put a vacuum gauge on it and when it misses you can see it loose vacuum. i think I probably have a very worn, stretched timing chain. My motor has 270,000 + miles on it and is due for a new motor as soon as I can figure out how to pay for it.

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    • #3
      Re: 1989 Suburban V1500 TBI 350 problems...

      Well, my suburban only has 150K on it, and the timing chain was replaced at about 95K, ran great until one day it died at a stoplight, which turned out to be the fuel pump.....at least that was one of the problems. The SES light came on briefly about a week before that, and it ran rough for about 5 minutes, but then went away.

      I checked the timing last night, with that brown wire unplugged and it is just over 0, which is where it is supposed to be....maybe I will try bumping the base timing up to 4 to see if that helps....not sure what else to do. I did notice that an end on one vacuum hose was looking a little worse for wear, so I cut it down to good hose and put it back on...didn't do anything. Maybe i will replace that hose just to be sure that isn't it.

      I checked all the grounds to make sure they weren't corroded....checked all the wiring once again, and ran my hands along all the vacuum hoses...they all look good except that one end coming off the manifold. Guess Ill just keep looking!

      Would a bad/dirty fuel pressure regulator or injectors give me these symptoms?? That is the only thing on the fuel system that isn't new (besides lines) and could probably use a good cleaning anyways. What is a good way to clean the fuel injectors/regulator?? I did notice some soot inside of the tip of the new exhaust...buring rich would cause backfiring out the exhaust, right? (lean would backfire out the throttlebody) or do I have them mixed up?

      Thanks
      Ryan
      2000 Chevy Silverado K2500 6.0
      1999 Chevy Suburban K1500
      1979 Chevy Silverado K10 454 4x4

      Comment


      • #4
        Re: 1989 Suburban V1500 TBI 350 problems...

        Another thing, how hard is i to completely remove the EGR syetem?? Not sure if my truck ever came with an air pump, but if it did, it is long gone. I can see a bracket that looks like it could have been for an air pump, not there is no fittings on the manifolds etc...

        I know I will probably get the SES light if I do the EGR delete, but what does it take to get rid of the code once the system is removed? New ECU? New Chip? Thanks!
        Ryan
        2000 Chevy Silverado K2500 6.0
        1999 Chevy Suburban K1500
        1979 Chevy Silverado K10 454 4x4

        Comment


        • #5
          Re: 1989 Suburban V1500 TBI 350 problems...

          You don't want to change your time beyond 2 degrees, the computer just corrects it and it will actually run worse without a tune. to remove the egr, use an egr block off plate and burn a new chip with egr removed (most people like to leave egr due to the benefits of better fuel economy) What does your injector spray pattern look like?
          That will tell much about fuel problems. What is your fuel pressure? yes, lean out tbi, rich out exhaust.

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          • #6
            Re: 1989 Suburban V1500 TBI 350 problems...

            How do I check the spray pattern? Can I use the timing light to do that? I will leave the timing alone for now...

            I may have to do some more research on the EGR Removal and reburing a chip ect..Gas mileage really isn't an issue, as it is a Suburban!

            Thanks for the info!
            Ryan
            2000 Chevy Silverado K2500 6.0
            1999 Chevy Suburban K1500
            1979 Chevy Silverado K10 454 4x4

            Comment


            • #7
              Re: 1989 Suburban V1500 TBI 350 problems...

              I haven't checked fuel pressure yet....don't have a gauge, but I have a few friends that may have one I can borrow. I will look more into the fuel issue, and hopefully find the issue and correct it!
              2000 Chevy Silverado K2500 6.0
              1999 Chevy Suburban K1500
              1979 Chevy Silverado K10 454 4x4

              Comment


              • #8
                Re: 1989 Suburban V1500 TBI 350 problems...

                My 87 V10 350 TBI misfired bad, but mine was whenever it was above idle. I unhooked the vacuum hose going to the EGR solenoid then plugged that port on my throttle body. Then it ran perfect. I avg. about 14 to 15 mpg without the EGR hooked up.
                2005 Chevy Corvette LS2 DD 105k
                1991 Firebird n/a 190k
                1987 Silverado 350 HSR 230k
                1980 Bonneville 350 Olds. diesel 198k
                1993 G20 350TBI 252k

                Comment


                • #9
                  Re: 1989 Suburban V1500 TBI 350 problems...

                  I am going to try to unhook the EGR and plug it, just to see if anything happens. I am going to check the fuel injectors with the timing light to see if I can see the spray pattern. Thanks for the help guys, and ill post what I find.
                  Ryan
                  2000 Chevy Silverado K2500 6.0
                  1999 Chevy Suburban K1500
                  1979 Chevy Silverado K10 454 4x4

                  Comment


                  • #10
                    Re: 1989 Suburban V1500 TBI 350 problems...

                    I unhooked my EGR ages ago, just plugged the vacuum lines. Truck never even noticed, no light, nothing.

                    Try base timing at six or seven. Yes it will make a difference and no it won't make it run worse without a tune that's completely wrong, I run 10 degrees advanced in my truck and have run it as high as 16 degrees, but had some spark knock going from part throttle to full throttle so I bumped it back, that's running 100 percent stock tune.

                    Backfiring out the exhaust sounds like the timing is too far retarded. Also check the TB base gasket. Wouldn't totally rule out the problem being internal though.
                    Last edited by ryan_thompson87; 09-21-2010, 07:25 PM.

                    87 K30-355 Vortec TBI/TH350/208/Dana 60/14FF/4.56s/Detroit/37"Bogger/Ult.TBI Mods/XtremeFI FPR vac. reference/EP241 Pump/LS1 Fans

                    07 GMC Sierra Classic - 2" Rough Country Full Leveling Kit/285 Duratracs/Gibson Exhaust/10% Tint/Billet Grille

                    Comment


                    • #11
                      Re: 1989 Suburban V1500 TBI 350 problems...

                      thanks for the clarification. I will have to check the base gasket, I guess I never thought of doing that. I will reset the base timing and see if anything changes. Didn't get a chance to check the fuel injection tonight, someone got a hold of my debit card and tried to use it at a gas station...luck was on my side and the lady behind the counter asked for ID. But for the life of me, I can't figure out how he got it. It is always in my wallet in my back pocket....the wallet was still there when I got the call, but my card was gone... I used it this morning to get gas in my wife's car....baffling! Anyways, no harm done, although I cancelled the card and they are sending me a new one, just in case....so no card for a few days...bummer!

                      Oh yea, the truck smells really rich when I shut her down, and it sometimes floods just trying to start it. Have to floor it to get it to start every once in awhile...

                      almost time for the trash pit!!
                      Ryan
                      2000 Chevy Silverado K2500 6.0
                      1999 Chevy Suburban K1500
                      1979 Chevy Silverado K10 454 4x4

                      Comment


                      • #12
                        Re: 1989 Suburban V1500 TBI 350 problems...

                        I would also get your ignition control module tested, even if you did just replace it. Since when the ICM goes bad it usually won't effect anything until the engine warms up.

                        Also since you mention your SES light came on at some point, find someone with a scanner and get your computer scanned. Then you will know the trouble code and that might help pin point the problem.
                        Last edited by robotic_junky; 09-21-2010, 08:45 PM.
                        2005 Chevy Corvette LS2 DD 105k
                        1991 Firebird n/a 190k
                        1987 Silverado 350 HSR 230k
                        1980 Bonneville 350 Olds. diesel 198k
                        1993 G20 350TBI 252k

                        Comment


                        • #13
                          Re: 1989 Suburban V1500 TBI 350 problems...

                          No new updates, its been raining cats and dogs out for the last 2 days and I have no garage at my disposal, so its been put on hold until it stops raining. I did put a can of seafoam into the tank to try to clean the injectors, and it has helped some, it idles better now, but I still need to check the spray pattern and get it scanned.
                          2000 Chevy Silverado K2500 6.0
                          1999 Chevy Suburban K1500
                          1979 Chevy Silverado K10 454 4x4

                          Comment


                          • #14
                            Re: 1989 Suburban V1500 TBI 350 problems...

                            I had the exact same problems as you. replaced ENTIRE distributor, not just cap and rotor. solved everything.
                            Thanks botman
                            1992 GMC 2wd RCLB - STOCK 350/4l60
                            1982 Chevy 2wd RCLB - Hot rod project awaiting mild 355
                            1978 GMC 4x4 RCLB - Fresh stock 350/TH350

                            Comment


                            • #15
                              Re: 1989 Suburban V1500 TBI 350 problems...

                              did you replace with a new distributor or a junk yard pick? I guess if I was going to replace it, I would probably just buy a new one. By the time I figure out this problem, everything on the engine is going to be new! Ive been driving it to work, which is only like 4 blocks, but it seems to be running better and better every day. It didn't backfire at all today while going to or coming home from work....and the throttle response is nice and crisp unlike it has been. Maybe its just the cool weather....i will continue to diagnose throughout the weekend and hopefully come up with some kind of solution. My brother has a TBI parts truck at his house, maybe I can pull the distributor just to try it before I go and buy a new one.

                              Thanks for the help guys! Keep the suggestions coming!
                              2000 Chevy Silverado K2500 6.0
                              1999 Chevy Suburban K1500
                              1979 Chevy Silverado K10 454 4x4

                              Comment

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