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88 Running Rough

Discussion in 'Chevy Trucks' started by Stan MI, Feb 21, 2009.

  1. Stan MI

    Stan MI Member
    Messages: 86

    88, 4.3 T.B.I.

    Runs OK for a little while, when it gets warmed up it starts to miss when you step on the gas. Will go back and forth between running rough and OK. Doesn't seem to be a pattern to it.

    Took the distributor cap off because I thought it might be cracked and separating when it warmed up but it looks OK. Could it be the coil going bad (going to have to read the Chilton just to make sure it has one) ?
     
  2. Stan MI

    Stan MI Member
    Messages: 86

    Going to replace the distributor cap and rotor today. Hope that helps !!!

    Checked out the Chiltons and it does have a coil. Didn't see any cracks.

    Anyone with any other thoughts ???
     
  3. Mike N

    Mike N Senior Member
    Messages: 148

    How old are the wires and plugs?
     
  4. wirenut

    wirenut Senior Member
    from nh
    Messages: 511

    possibly the fuel pump
     
  5. CityGuy

    CityGuy PlowSite Fanatic
    Messages: 16,987

    PCV valve?
     
  6. Stan MI

    Stan MI Member
    Messages: 86

    Replaced the dist and rotor, No difference. Ran 4 oz. ofeafoam through the vacumm balance in tank, no difference.

    Plugs and wires are orig I think. Looked for a spark last night, didn't see anything. There so old though could still be bad.

    How would I test the fuel pump ? Thought about changing the fuel filter but I don't know where it is. Any help ??

    PCV. I can blow air through it when I take it off so I don't think it clogged, is there another test ??

    Thanks for the HELP. I really appreciate it. Hate to take this truck in for service. Seems like it should be something simple, (I hope).
     
  7. tom_mccauley

    tom_mccauley Senior Member
    Messages: 465

    I would seriously look at the pickup coil on the distributor ( I assume it is hard starting as well?)
     
  8. Stan MI

    Stan MI Member
    Messages: 86

    It starts very well. Most of the time the truck sits outside. This has been a exceptionally cold Winter so you would think starting would be a problem, fires right up. Turns over quite well.

    It seems like the rough running starts after it has been fully warmed up a while. That makes me think the coil might be bad.

    You mention the, "pickup coil on the distributor", does that mean the coil NEXT to the distributor or is there another one ??? Just want to make sure.

    Thanks for the help !!
     
  9. CityGuy

    CityGuy PlowSite Fanatic
    Messages: 16,987

    I'm guessing that the fuel filter is original. It should be located on the insdie frame rail near the rear tire. It looks kinda like a pop can. I would try replacing this it's relatively easy and inexpensive.
     
  10. tom_mccauley

    tom_mccauley Senior Member
    Messages: 465


    The pickup coil is located IN the distributor you have to completely dis assemble the dist. to get to it. It is a fairly common problem with mid-late 80's gm products as the pickup's are made out of plastic and are prone to drying out from heat and cracking. Mine started out as an off idle miss, then to stuttering at highway speeds, finally it would not start at all when it finally broke.
     
  11. Stan MI

    Stan MI Member
    Messages: 86

    The pickup coil is located IN the distributor you have to completely dis assemble the dist. to get to it. It is a fairly common problem with mid-late 80's gm products as the pickup's are made out of plastic and are prone to drying out from heat and cracking. Mine started out as an off idle miss, then to stuttering at highway speeds, finally it would not start at all when it finally broke.


    Would that be something that would work when the truck was cold and not after it warmed up ???
     
  12. snowcan

    snowcan Member
    Messages: 52

    If you have not replaced the distributor shaft you need to do it along with the pick-up coil. This is a long time tsb for these trucks for the symptom you are describing, you can only get it at the dealer, I think around $60.00.
     
  13. tom_mccauley

    tom_mccauley Senior Member
    Messages: 465


    Yes, that is how they start to go bad, when it heats up it will expand allowing a gap
     
  14. jimz2500

    jimz2500 Member
    Messages: 43

    Just a thought. Egr and/or egr control solinoid. If it runs ok down the expressway but runs like snot off idle I would check these.
     
  15. REAPER

    REAPER 2000 Club Member
    from 60050
    Messages: 2,228

    Before you start tearing your engine apart try changing the spark plug wires 1st. Then slide under the truck under the drivers side door and look for the fuel filter along the frame rail. looks like a pop can as mentioned before. It is probably going to be rusted at the ends so get ready to cuss. Spray the connections with a lot of nut buster of some sort and let it set a while.
    Then replace the filter with line wrench's. Do not use just a open end wrench or you will round off the connectors and have to get the vise-grips and cuss more meanwhile maybe twisting the braided line that goes up to the TBI.

    Or you could take it to a shop and ask them to replace the filter only. May cost more but will save you a lot of time and knuckle skin.
     
  16. Stan MI

    Stan MI Member
    Messages: 86

    Is there a way to test the pick up coil (in the distributor) so I know if its bad or good ??
    Also, haven't looked yet but I will probably change the fuel filter as well since I am sure it OEM. Starting with a blast of WD40sounds like a good idea.

    Never heard of line wrenches before. I know I can surf around and find something on them. Should I look for anything special ?? I thinking similar to sockets, you can purchase 6 or 8 sided. Is there anything like that to these ?
     
  17. augerandblade

    augerandblade PlowSite.com Addict
    Messages: 1,054

    Look guys if it start well when its cold its not a electrical/ignition problem. I would go for something to do with the fuel mixture. EGR. Vacuum hoses that might kick in when it warms up. But what do I know I plow snow for a living :dizzy:while the facility manager is holding their significant other tight.:jester:
     
  18. CityGuy

    CityGuy PlowSite Fanatic
    Messages: 16,987

    Here is an example of line wrenches also know as flare nut wrenchs.


    http://www.sears.com/shc/s/p_10153_12605_00942012000P?mv=rr
     
  19. augerandblade

    augerandblade PlowSite.com Addict
    Messages: 1,054

    If the filter connections are seized just cut em with a brake line cutter, go to your auto supply shop, they got the proper ends to hook into the new filter, then use the brass connecters( dont know the proper term) to fit the two cut lines together. I know it works I did this to my old 89 Chevy
     
  20. sechracer

    sechracer Senior Member
    Messages: 478

    The connectors that Auger is talking about are commonly called compression fittings. They make the repair ends for most vehicles. Fairly cheap too, I think they are like $10 a side or something.

    Like mentioned before, I would pull the EGR off of it and see if it has something plugging it. Also check to see if the pintle inside moves easily. Being that it runs good until it starts to warm up, it is most likely not a fuel problem being it should require more fuel when cold.