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More problems... '89 Burb stumbling off idle ***UPDATE***

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Jul 27, 2003.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    More problems... \'89 Burb stumbling off idle ***UPDATE***

    <font color="red"> See bottom for the update!!! </font>

    Ok... If I wasn't so damn low on cash right now I'd buy new injectors, new fuel pump, a new O2 sensor, and a control module too. Unfortunately, I really AM broke... so I need to have everyone's best guess on this.

    I fixed the stalling problem I recently had by adjusting the timing to 4*. I also replaced the IAC, and cleaned the TPS. It idles at a nice low RPM now, that feels right. Problem is... I leave from a stand-still, the motor bogs for a moment and then it comes back and makes ok power but you can feel that its not even power... thru the RPM band in first gear you can feel the power output on the motor changing at different places off every light. Top end power seems very lacking for my engine combo too.

    Long story short... I see three obvious places I should look at:

    1. Ignition module (I had a code 42 ONCE that I can no longer reproduce after resetting the codes yesterday) Wells replacement (PN DR140) @ AutoZone for $25.99.

    2. Fuel pump? I need a CHEAP way to test the fuel pump... key word here C H E A P! AutoZone carries it (AC Delco PN EP386) for $38.99.

    3. Injectors. I think I am going to rebuild the set I have in this motor regardless tomorrow night, just to see if it helps. I am pretty sure I can do this for nothing more than a can of good carb clean, and a pair of snap ring pliers that I already own.

    Ideas? I have already spent too much money this paycheck on this thing... and I really need it to be reliable seeing as its my DD. Can anyone give me testing procedures for the control module and/or the fuel pump? I've got a multi-meter, but no fuel pump pressure tester... (I've got a vacuum gauge that I think claims it can test fuel pressure...?)

    I am at wit's end here ppl... sorry for the long panicy post. I wish this F[I HATE JEEPS]ING /forums/images/graemlins/grin.gif thing would just WORK already! Thanks for all the help guys/gals! /forums/images/graemlins/burb.gif

    -Dan
     
  2. yeild2me

    yeild2me 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    Mine did the same thing...and come to find out the alternator was on the way out....replaced it and it was fine.

    just something else to check (and its free)

    Good luck and keep us posted

    Rob
     
  3. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    Voltage displays on the dash meter at just above 13V at idle. Should I just pull the ALT and have it tested?

    The other odd thing about this Burb is that it SAT for at least one year since the last time it ran... the motor had blown... and it took me some time to get it put all back together. So there could be plenty of weird things going on with it...

    Thanks for the idea Rob! /forums/images/graemlins/wink.gif

    -Dan
     
  4. yeild2me

    yeild2me 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    If your readin 13 v ( considering the gauge is correct), its prolly fine. My gauge was inop so I didnt see it coming. I love my TBI, but it can be a Beotch to tracj down problems...!!

    Rob
     
  5. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    I think there is a fuel problem for sure...There is an adapter you can get at NAPA that goes between the fuel line and the TB...I think it is like $20, and it has a 1/8 NPT port to plug in a fuel pressure gauge. Also. the fuel pumps are designed to run at no less than 13.5 psi...If you voltage is truly only 13 or even less on hot days, that could greatly affect you fuel pressure...fo rinstance, I have my FP set on my 454 to 14.2psi and that is at 14.1 volts..as soon as my truck gets nice and hot on a 90* plus day, and the voltage drops to say 13.75Volts, the pressure drops almost 1 psi.. that doesn't seam like much, but if you already have a weak pump or you factory regulator is set kinda low, it could really affect the performance...

    On my 87, the FP was weak...but it was enough to run my 350 well enough...as soon as I put my 454 in there I couldn't give it ANY gas or it would stumble and try to die...I hooked up a FP gauge and it was only putting out 8.5 psi at idle /forums/images/graemlins/eek.gif when I would tip in the throttle, it would drop to 7 and stumble badly...



    Dan here is what I would do...First dicnnect the FP harness towards the rear near the fuel tank and verify that you are getting your total system voltage at the connector. If you system voltage is 13 and you are only getting 11.5V at the harness plugin, there is a problem somewhere and you need to fix it...

    Second, get you alt tested...13V seems kinda low in my book...mine is 14V +/- .25V ALL THE TIME...

    Third, you can alter your fuel pressure at the TBI FOR FREE...Make sure you have some new TB gaskets before you remove it. Remove the TOP of the injection pod of the TBI (there are like 8 torx bolts you can see right on top of the injection pod) Turn it over and there are 4 torx bolts holding the fuel pressure regulator on...Remove them (while holding the FPR can as there is a spring under compression in there) Remove the spring... Then, with it stretched out a bit (under tension), heat it up with a torch...This will make the springs static lenght LONGER than it was before...therefore, it will provide MORE pressure against the regulator diaphragm at the fixed installed height of the Stock regulator...I did just the opposite of this (heated the spring under compression) to lower my FP and it worked great...I was able to lower it by 2 psi which is what I was aiming for /forums/images/graemlins/thumb.gif

    Not just assemble the TB again and test drive if the condition still exists...TEST THE FP, as the pump is probably croaking...
     
  6. rampage

    rampage 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    [ QUOTE ]
    The other odd thing about this Burb is that it SAT for at least one year since the last time it ran...

    [/ QUOTE ]

    Is it possible that while it was sitting rust built up in the tank and is now interfering with fuel flow?
     
  7. jjlaughner

    jjlaughner 3/4 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    Maybe its just me (I dont know a lot about motors) but it sounds kind of like a fuel filter /forums/images/graemlins/ignore.gif
    Grant it could be the pump too, and I agree on the alt/fuel pressure thing (I noticed the difference in my stock vehicle when I put in the new hi-amp alt for the lights and stereo crap (maybe even clean the battery connections and ground)).
    Other things I'm kind of wondering the fuel line could be kinked or maybe some sealent on a connector is blocking the line, of course the filter again if rust from a sitting tank broke loose. Can you test the pump at the tank and at the throttle body?
    If it where the injectors I would think the idle would be off along with the top end, unless you have one of the injectors not firing starving it at high RPM's.
    Is the coil new also? Connections on it are good?
    I dont know, just tossing out some ideas /forums/images/graemlins/tongue.gif
     
  8. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    There is a new fuel filter in the truck too... I did that before I started it. The one that was in there before was pretty clean too... so I don't think its a fuel contamination problem. Brand new Optima battery too that I yanked from the K5 when I took it out of service (no corrosion here!) The reason this is a WIERD DEAL is because the loss is getting worse and worse... it ran fine the first couple of days... but Sunday morning it was obvious that it was pissed off about something.

    Tried to drive the fat whore to work today, and it was VERY badly stumbling and had MASSIVE lack of power. I turned around after 3 blocks and got my wife's minivan. Damn this thing. Its just not my week. And OF COURSE, I FILLED the tank on Saturday night. Its full to the top. Gotta love that.

    -Dan
     
  9. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    I would pull the fuel filter again and take a look. If the truck sat for awhile with little to no gas in the tank than likely there was some corrosion build-up in it. The more you drive the more junk is getting sucked through the lines.
     
  10. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    Hey, when I replaced my FP, the tank was full too..a little trick..? Unhook the feel line from the TB and route it into a gas can...Then Pull the relay off the firewall and just the terminals for the 12V hot and the Fuel pump power terminal...This will give the FP power and the FP will run and then fill up the gas can...Every time the tank fills up, pull the jumper and fill up the wifes car or pawn it off to neighbours...thats what I did...

    Chirs
     
  11. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    [ QUOTE ]
    The reason this is a WIERD DEAL is because the loss is getting worse and worse

    [/ QUOTE ]

    Im thinking fuel pump at this point buddy...Electric pumps are really wierd...sometimes they just quite, other times the SLOWLY go out, or just give up on hot days ort when the tank is low on fuel...

    Chris
     
  12. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    HAHAHAHHA... thats a good idea! The wifes van always needs gas. Figures that the damn pump would wait to croak until I put $40 worth of gas in! /forums/images/graemlins/angryfire.gif Ah well... Looks like I will have to work on that... maybe tonight if it stops raining.

    Thanks Chris!

    -Dan
     
  13. zcarczar

    zcarczar 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    I almost bet its the Injectors. I just finally got mine fixed on Saturday. I was also having the same problems you were, lack of power, stumbled like hell and ran like [I love Jeeps]. I ordered a set of the turbo city injectors and it fixed EVERYTHING! It fixed my surging idle, lack of power, surge on accel, and lean condition. Just throwing out a suggestion there.

    If you have a Laptop I strongly suggest taking a look at winaldl. Check your O2 sensor voltage, map sensor readings and TPS readings while the truck is acting up. This will tell you a lot, .475 mv is 14.7:1 fuel ratio on the O2 sensor, higher mv its rich, less mv its lean. Hope that helps you some.
     
  14. Foy

    Foy Registered Member

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    Re: More problems... \'89 Burb stumbling off idle

    There's a heckuva lot I don't know, but one thing I've had experience with is old, bad fuel. One of my other addictions is old IH Scouts, and many of them that you come across have old, stale fuel. Modern fuel is much worse, having a "tank life" of 40-60 days, depending. With that 'Burb having sat for a year, and if you didn't drain the tank from the get-go, then poured another 40 gallons in on top, and now it's getting worse, I'd have to wonder if you had a tank of varnish to start with, and now have a tank of diluted varnish and sediment. It won't help the sediment, if present, but you may be able to salvage the load of fuel by adding a marine product such as Stor'N Start. I use it in most every batch of fuel I put in the 85 gallon tank on my boat because it sometimes sits for over a month (especially in winter) and my carb-fouling, varnished-up days are over. Dump in about a double dose, and limp around the block sawing the wheel back and forth to mix it up good, and let it idle for 10-15 mins, then shut down and let it sit overnight. You could be surprised. One other thing I've found out--a plugged cat converter will make your truck behave badly, too, and I've had a '79 IH whose cat went bad slowly and about drove me crazy in the process until I figured it out. On the other hand, a couple of years back, my '90 Suburban cat plugged up practically instantly--seemed to run fine on the way out to supper, the cranked her up leaving, and she'd barely idle, and I had to just about floor it to move it down the street. If you've got a cat, mebbe she's plugged up. Easy enough to figure out--pull it off and see how it runs. Warn the neighbors first--could be a little loud.

    HTH,
    Cooper
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: More problems... \'89 Burb stumbling off idle

    [ QUOTE ]
    Modern fuel is much worse, having a "tank life" of 40-60 days, depending.

    [/ QUOTE ]

    As long as the tank is capped, 40-60 days is NOWHERE near the maximum shelf life of gasoline.

    I know a lawnmower isn't the best comparison, but it's a small gas engine, and they are arguably the most finicky internal combustion engine you will deal with.

    My gas sits for at least 6 months straight during the "winter" here, and either in a GI gas can or plastic Blitz (in an unheated covered shed) it works fine afterwards.

    I've had gas in my car for that long without problems as well.

    I'm not saying it *can't* be a problem, and that dumping a few gallons (or more) of good gas in to mix with isn't a good idea, but scaring people with 40-60 days of shelf life doesn't help. People will be pulling their tanks after their vehicle is parked in the garage for a month.

    I'd be much more concerned with the residue leftover in the carb when the fuel dries out, which is an almost 100% certainty from what I've seen.
     
  16. Foy

    Foy Registered Member

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    Re: More problems... \'89 Burb stumbling off idle

    Dorian- My purpose was not to scare people into pulling tanks if they haven't driven their vehicles in a month, but instead to repeat common belief among boaters who deal with finicky 2 cycle outboards and 4 stroke marine engines regularly. Conventional wisdom there is 40-60 days before meaningful degradation of the fuel quality starts--not to be confused with a situation where the tank must be pulled. The recognized and accepted (and effective, in my case) solution is to add stabilizers, either when fuel is added, or, if there's been a period of a few months since untreated fuel was added, use a so-called "store and start" fuel conditioner. I don't know of anybody who has recommended pulling a tank, often requiring sawing the decking up and re-glassing it back in, just because the fuel was old and stale.
    I'd be interested to know if your information that 40-60 days is "nowhere near" the shelf life for fuel is from your own lawnmower experience, or from other sources, and what those sources may be. Perhaps millions of boaters are adding fuel stabilizers needlessly. I think not, however, as my recollection is that even the oil companies have recommended not storing gasoline for periods of &gt; a month or so without adding stabilizers, due to the degradation issue.

    The bottom line is that I was simply offering the poster a way to get his Suburban running better--one that had been touched on in earlier posts but not as to the fuel degradation side of the issue.

    Oh, and your lawnmower may be capped (mine sure is), but most truck fuel systems are not--they're vented.

    Foy
     
  17. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle ***UPDATE***

    Cooper-

    Thanks for the clarification. And being that you are new to CK5, I'd like to thank you for your cool headed response to Dorian's reply (not that Dorian's concern wasn't valid). Takes most folks quite some time to learn the art of debate w/o anger... and for a high school student, I'd say you are wise beyond your years. Enuf said there...

    ON TO MY PROBLEMS... which still exist BTW... EVEN AFTER:

    1.IAC motor was replaced
    2.TPS cleaned and calibrated
    3.Timing set to 4*
    4.Fuel pump replaced with an ACDELCO pump, helped but didn't fix it.
    5.Ignition module tested OK @ AutoZone on wells test unit, and reinstalled with thermal grease.
    6.Ignition coil tested IFFY (couldn't get a stable reading off the coil wire post) so REPLACED the coil, and STILL didn't fix it.
    7.I swapped injectors from my K5 motor into the Burb and for a little while I thought I had fixed it. This morning, its back to its same old habbits.

    So after all that work, the damn thing still isn't running correctly. Same problems as before... random (what feels like) misfires through the RPM range, and lack of top end power. You can feel the motor going between stages of running fine and stuttering, due to the change in power output.

    The only things left are:
    1.Distributor pickup
    2.Alternator
    3.voodoo

    Ideas? Please help me before I drive this farkin truck into a big brick wall. /forums/images/graemlins/shocked.gif

    Thanks all...

    -Dan
     
  18. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: More problems... \'89 Burb stumbling off idle

    Dorian-

    You don't happen to know where I can find a vacuum diagram (online) for this truck do you? I've had a few ppl suggest vacuum problems... but I bought a gauge and the motor is pulling 20# at idle.

    Thanks,
    -Dan
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: More problems... \'89 Burb stumbling off idle

    Nope, no clue on the vacuum diagrams. Only heard of people "looking on the sticker on the core support", but I don't think even the service manuals have the vacuum diagram. I could be wrong on that, it SHOULD be in the service manual, but I don't think you'll find it. Maybe because there are so many variations each year.

    I pulled a few of the stickers off of trucks in the wrecking yard, but however they are made, they aren't made to be removed. Maybe heat would help, but I don't take a hairdryer to the wrecking yard.

    Perhaps someone who has a TBI truck service manual can comment on that.
     
  20. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: More problems... \'89 Burb stumbling off idle

    Is it running ok once you get to steady cruise?
    Is it running ok when your start it till it goes closed loop?
    Is it going closed loop? There is a way to verify by jumping the ASDL post but don't know it off the top of my head.

    This may be a EGR problem. EGR is closed when in open loop and closed at idle. It also closes when you acclerate.

    Quick check is unplug the vac line to EGR while it's cold Drive it and see how it behaves. It will throw a light if it's in closed loop.
    On my 88 I was having a serge problem. Turned out to be EGR. The EGR could be sticking open. On my 88 the EGR has a control solonoid. It was sticking. I put a few drops of air tool oil in it and a new EGR and it cured my problem. Simular situation, my truck was hardly used for 1.5 years 1,000 miles).

    Now if the truck is not going closed loop once warm it would be like driving with the choke on. Meter out the ECM's temp sensor. Symptoms would be the same as what your expessing.
     

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