87 FJ60 rough running, bucking at mid RPM'S

Discussion in '60-Series Wagons' started by OLIFANT, May 18, 2011.

  1. OLIFANT

    OLIFANT

    Messages:
    17
    My truck has been running perfectly for the past few years. On the way home last night I took a turn which required a down shift into second. When throttling back up the truck bogged down around 1200 rpm. Feathering allowed the rpm's to climb, but not under load. I have checked the air filter and intake- it idles better when the intake is blocked off which makes me think it is a vacuum issue.
    I had to leave for work, but plan on picking up new hose on the way home to begin troubleshooting.
    Any thoughts on what else could be causing such a sudden issue? The fuel system seems to be fine, I think air is the problem.
    Thanks
  2. OzarkMtnCruiser

    OzarkMtnCruiser

    Messages:
    95
    Location:
    Little Red River
    hey guys newbie here- first cruiser, 1985 w/ 140K miles and I've had her for one week and 1K miles, trouble free. I have the same problem, low speed in second gear my cruiser will buck and lurch forward until the speed picks up.. other than that it idles fine, runs fine. Any suggestions would be appreciated.

    Cheers-
  3. trucruiser

    trucruiser

    Messages:
    654
    Location:
    Northern Colorado
    Check for vacuum leaks and make sure your manifold bolts are tight to the head. A couple of first things to check.
  4. elripster

    elripster

    Messages:
    511
    Location:
    San Diego
    I had this issue and it was the EGR opening when it shouldn't. I had a little over 16 inches of Hg on the vac gauge which seemed normal from what I could tell so I was confident I didn't have a vac leak. My fix was by elimination. I eliminated the EGR system and it fixed it. If you cannot do that, download the FSM and go through the checks. It won't take long to do, it's a fairly simple system.

    Frank
  5. Gurr

    Gurr

    Messages:
    445
    Location:
    Santa Cruz, California
    You can look up EGR bypass in the search function.

    My truck would lurch/buck if I was trying to keep a constant speed. After much bypassing and emissions checks I found that it was the secondary diaphragm on the carb.

    A way to check it is to put a paper clip on the rod that comes out of it and go for a drive. If the clip moves, the diaphragm should be good, and if it doesn't...order a new one($40)

    Specter Off-Road Land Cruiser Parts - Page 042 Land Cruiser Carburetion

    part #16 in the 75-87 carb diagram
  6. OLIFANT

    OLIFANT

    Messages:
    17
    Thanks guys. No progress today, other than the wifey picking up vacuum hose as we have been getting rain all day. Hopefully I can resolve this tomorrow.
  7. OzarkMtnCruiser

    OzarkMtnCruiser

    Messages:
    95
    Location:
    Little Red River
    thank's for all the suggestions- after doing some searching/reading on the board, it seems this is a fairly common problem with a number of different solutions that have worked for people in the past..

    Gurr what do you mean by "if the clip moves"? thanks
  8. OLIFANT

    OLIFANT

    Messages:
    17
    I also have another question- I am half way through the hose swap, nothing has changed yet. By chance I dropped my knife and noticed as I picked it up that the seam on my muffler is blown wide open leading me to wonder if back pressure could cause this- or lack thereof I should say.

    And one more thing, all of the vacuum lines to the carb have been replaced, yet when I manually throttle the truck at the carb there is a hissing which sounds like it is coming from somewhere near the linkage- any thoughts?
  9. NYNick

    NYNick

    Messages:
    479
    Location:
    Westchester County, NY
    I was having a similar issue for months..truck was basically un-driveable..buck buck misfire misfire lurch lurch...
    Disconnected the TPS today and the truck runs great. Think a new one is in order.
    Try disconnecting it and running the truck. Just an idea...worked for me!
  10. OzarkMtnCruiser

    OzarkMtnCruiser

    Messages:
    95
    Location:
    Little Red River
    well i decided to try the golf tee trick first.. didnt have a second piece of hose, so i stuck a toothpick in the EGR (not far,I didn't want to create a problem trying to fix problem) and drove around the neighborhood and that seemed to "fix" it.. no lunging or jumping so i concluded the EGR valve needed to be worked on.

    I stopped, put everything back and took off- when i got close to home I shifted to second expecting to have to work the clutch a little to compensate for the ride when i accelerated.. but when I gave it some gas, low and behold no lunging, nothing it was a smooth acceleration.. I couldn't believe it, drove good all day-

    knock on wood we'll see what happens tomorrow- Thanks for all the suggestions. Good luck OLIFANT
  11. specialk396

    specialk396

    Messages:
    458
    Location:
    Waynesboro, Va
    Sounds like your muffler was clogged. Keep us updated.

  12. OzarkMtnCruiser

    OzarkMtnCruiser

    Messages:
    95
    Location:
    Little Red River
    well another day.. problems is back and after pulling on a couple of the vacuum lines i found two that were not connected and one was capped. - yea i know.
    [​IMG]

    the hose on the left connects to the throttle positioner (beside the green plug) where does it route?
    the hose that's capped connects here(pic below) where does it route??
    [​IMG]

    Thanks for the assistance..
  13. Looking at all that smog hardware makes my head hurt.
  14. OzarkMtnCruiser

    OzarkMtnCruiser

    Messages:
    95
    Location:
    Little Red River
    after talking with some folks it looks like these hoses control the idle up speed for the AC- and connect to p/n 88691 VALVE, MAGNET (FOR IDLE UP DEVICE).
    Does anyone know where this part is mounted? By the diagram it appears the have a 90 degree clamp so Id assume it mounts to the firewall or wheel well but i cant find it- I did find a female electrical connection on top of the wheel well that's just sitting there.. Is that where it was and someone cut it out? Could this be part of the lunging problem or is this a separate issue? Many thanks..
    [​IMG]
  15. OLIFANT

    OLIFANT

    Messages:
    17
    Okay, so all of the vacuum hoses have been replaced with the exception of the three that run along the carb on the engine side of the carb. When started and given gas the truck runs well, which it was not before. It still idles roughly @ 600 RPM, bouncing in a rough idle until it dies.

    I am sure it is getting plenty of air and fuel. Could this now be a back pressure issue?
  16. elripster

    elripster

    Messages:
    511
    Location:
    San Diego
    600 RPM seems a bit low for an idle. Mine idles around 800 - 1000 which might be a bit high but I don't mind. Carburated straight 6's always seemed to have imbalanced carburation between the cylinders due to the difference in intake runner length so often idle a bit roughly. Sometimes the higher idle helps.

    I'm sure others will have more advice.

    Frank
  17. tag3

    tag3 Doofus SILVER Star

    Messages:
    1,528
    Location:
    Central coast Cal.
    My stutter ended up being the EGR rubber had ripped and on opening let in air instead of exhaust.
  18. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

    Messages:
    7,928
    Location:
    Lancaster, Ohio, USA
    Ozark, PN 88691 is usually mounted to the vertical inner fender w/ a 6x1 bolt (10mm hex). It does not effect how the truck runs. Only idle quality w/ the AC on is effected.

    Olifant, no it is not an exhaust pressure problem. The idle mixture is wrong. Either the mix screw needs adjusted, or there is a manifold vac leak, or the idle circuit is partially plugged w/ junk.
  19. OzarkMtnCruiser

    OzarkMtnCruiser

    Messages:
    95
    Location:
    Little Red River
    thanks Jim yea I found the bolt on the fender, sans the switch. Seems my problem with the lunging could be the EGR valve- i have it bypassed now and the truck is running fine(two days now).. could this cause any problems long term? Thanks again.
  20. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

    Messages:
    7,928
    Location:
    Lancaster, Ohio, USA
    A lack of EGR on a 2F is not likely to cause problems.

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