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Bad stumble on acceleration coming home last week- fixed!!

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  • Bad stumble on acceleration coming home last week- fixed!!

    On my way home from getting all the parts outlined elsewhere my truck started running worse and worse, especially going uphill. It would idle, but when it got under load it would start stumbling and, I thought, missing. I took a longer route home with fewer hills to give myself some peace of mind. When I got home and pulled into the drive it was idling fine. When I would gas it it would stumble. I popped the hood and you could hear a distinct whistling sound that was not there before.

    Is there anyone who DOESN'T think it's a vacuum leak?

    I couldn't find it... but as tired and tense as I was I just wanted to get everything unloaded and get into the house to eat pizza and watch the Braves.

    I'll tackle it Monday...
    Last edited by Dirtball; 04-18-2009, 07:09 PM.
    Paul
    1979 Cherokee N/T
    360/TH400/Qtrac/D44s/rear Lock-right
    6 inch Hell Creek all spring lift
    34x10.50 Super Swamper LTBs
    http://i54.photobucket.com/albums/g1...t/100_1394.jpg
    http://i54.photobucket.com/albums/g1...t/100_1390.jpg
    http://i54.photobucket.com/albums/g1...100_1387-2.jpg

  • #2
    Any mods to the ignition? I fought the "stumbles" for years. It wasn't until I went to a larger cap on the rotor (juice box) upgrade that I finally got rid of it. Check the inside of your cab for carbon tracks leading to the various pickup points for the spark plugs. Was it raining or the engine wet causing a spark short somewhere? Also check your vacuum, you might have a leak in a hose.
    1976 Chief
    http://www.ifsja.org/forums/vb/showthread.php?t=96753

    Comment


    • #3
      Yeah, I kind of figured/hoped that the whistling sound I heard was a vac leak. I'll get it into the garage tomorrow and get it checked out...
      Paul
      1979 Cherokee N/T
      360/TH400/Qtrac/D44s/rear Lock-right
      6 inch Hell Creek all spring lift
      34x10.50 Super Swamper LTBs
      http://i54.photobucket.com/albums/g1...t/100_1394.jpg
      http://i54.photobucket.com/albums/g1...t/100_1390.jpg
      http://i54.photobucket.com/albums/g1...100_1387-2.jpg

      Comment


      • #4
        How did you check for vaccume leaks? A old trick I have heard, is to take a can of starting fluid or carb cleaner and start spraying the carb, gaskets, and anywhere else that vaccume may leak. If its leaking, it will suck the carb cleaner in and you will hear the idle change.
        79 Cherokee Chief 401/T18/D20, MPFI fuel injection, hydroboost, otherwise stock.
        Future mods: Caddy 500/NV4500/NP205, HP D60 front D60 smooth botom rear, 5.13 gears, 35x12.50's on H1 beadlock wheels. Warn M12000 winch.
        93 Wrangler 4.6 stroker/AX15/NP231,SYE,CV, OME 2.5 lift, front hub conversion/big brakes, 31X10.50's Warn M10000 winch.

        Comment


        • #5
          Whisle as u know is a dead giveaway to a vac leak. However. You engine might be suffering from fuel starvation. Just for fun replace the filter. I like to blow in the newone and in the removed one to see how clogged up they are.
          Terry

          1970 Kaiser Wagoneer -SOLD (currently getting built by new owner)
          Build thread-http://www.ifsja.org/forums/vb/showthread.php?t=103447
          1979 Cherokee Chief WT 360. SOLD
          1977 Cherokee Chief WT Sport 401. SOLD
          1975 International Scout II (My DD)

          Comment


          • #6
            Originally posted by JeepsAndGuns
            How did you check for vaccume leaks? A old trick I have heard, is to take a can of starting fluid or carb cleaner and start spraying the carb, gaskets, and anywhere else that vaccume may leak. If its leaking, it will suck the carb cleaner in and you will hear the idle change.
            I got some starting fluid today... but by the time we got home from Wally World and ate my Monday Night Comedies were on... it's my one big TV night.
            Paul
            1979 Cherokee N/T
            360/TH400/Qtrac/D44s/rear Lock-right
            6 inch Hell Creek all spring lift
            34x10.50 Super Swamper LTBs
            http://i54.photobucket.com/albums/g1...t/100_1394.jpg
            http://i54.photobucket.com/albums/g1...t/100_1390.jpg
            http://i54.photobucket.com/albums/g1...100_1387-2.jpg

            Comment


            • #7
              I would be very careful about spraying starter fluid around the engine (as in I wouldn't do it!). It's highly combustible whereas carb cleaner is not. If you really really want to use starter fluid, have a fire extinguisher strapped to your helmet.

              Steve
              '76 Waggy, TH400, Quadratrac and a fourOH!one Sold

              My other car is a Viner Pro Team...no wait, my other car is a Masi Speciale...nonono, my other car is a Bianchi 928SL

              Comment


              • #8
                Yea, carb cleaner is better, but starting fluid will work. Just do it with the engine cool, and only doo it in short bursts. Dont hose it down too much. Keep it away from the exhaust!! But you knew that already.
                79 Cherokee Chief 401/T18/D20, MPFI fuel injection, hydroboost, otherwise stock.
                Future mods: Caddy 500/NV4500/NP205, HP D60 front D60 smooth botom rear, 5.13 gears, 35x12.50's on H1 beadlock wheels. Warn M12000 winch.
                93 Wrangler 4.6 stroker/AX15/NP231,SYE,CV, OME 2.5 lift, front hub conversion/big brakes, 31X10.50's Warn M10000 winch.

                Comment


                • #9
                  I did the starter fluid thing and, since there are no vacuum hoses running anywhere near my exhaust manifolds, everything went fine. Also, no vacuum leaks.

                  However... today, I replaced the fuel filter. Simplest fix first as I usually suggest on here. And guess what? That was the fix. Isn't it amazing? I didn't really think it was electrical since it wasn't backfiring or spitting/sputtering. I have no clue what the whistling sound was. It's not doing it now (and it wasn't doing it this morning when I drove it and it still had the stumble).

                  Anyway, once again, I get lucky and have a quick fix.

                  Now if that new Qtrac and Lockright would both just jump in there as easily.
                  Paul
                  1979 Cherokee N/T
                  360/TH400/Qtrac/D44s/rear Lock-right
                  6 inch Hell Creek all spring lift
                  34x10.50 Super Swamper LTBs
                  http://i54.photobucket.com/albums/g1...t/100_1394.jpg
                  http://i54.photobucket.com/albums/g1...t/100_1390.jpg
                  http://i54.photobucket.com/albums/g1...100_1387-2.jpg

                  Comment


                  • #10
                    I like those clear plastic fuel filters. That way you can see whats in there, and when it needs changed.
                    79 Cherokee Chief 401/T18/D20, MPFI fuel injection, hydroboost, otherwise stock.
                    Future mods: Caddy 500/NV4500/NP205, HP D60 front D60 smooth botom rear, 5.13 gears, 35x12.50's on H1 beadlock wheels. Warn M12000 winch.
                    93 Wrangler 4.6 stroker/AX15/NP231,SYE,CV, OME 2.5 lift, front hub conversion/big brakes, 31X10.50's Warn M10000 winch.

                    Comment


                    • #11
                      Originally posted by Dirtball
                      I did the starter fluid thing and, since there are no vacuum hoses running anywhere near my exhaust manifolds, everything went fine. Also, no vacuum leaks.

                      However... today, I replaced the fuel filter. Simplest fix first as I usually suggest on here. And guess what? That was the fix. Isn't it amazing? I didn't really think it was electrical since it wasn't backfiring or spitting/sputtering. I have no clue what the whistling sound was. It's not doing it now (and it wasn't doing it this morning when I drove it and it still had the stumble).

                      Anyway, once again, I get lucky and have a quick fix.

                      Now if that new Qtrac and Lockright would both just jump in there as easily.
                      I had a whistle and it turned out to be my carb gaskets.
                      Daniel
                      I have some good news and some bad news. The good news is that I always allow each student one free pass in my classes. The bad news is that you have now used yours for this class. Doug

                      Comment


                      • #12
                        Yep, carb gaskets can whistle.

                        Once I had a whistle I couldn't track down. It didn't happen all of the time. One day I took the carb off for something unrelated and found the plastic spacer was cracked. I swapped it out and never had anymore whistle.
                        79 J10 Honcho 360/T-18/D20
                        Summit 8600 cam, GM TBI
                        78 Wagoneer 360/TH400/QT

                        Comment


                        • #13
                          I like those clear plastic fuel filters. That way you can see whats in there, and when it needs changed.
                          They pulled those off the shelf here in CA. They are all the white plastic now.
                          I think the Alcohol in the fuel may have been an issue but not sure.

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