Carb issue, am I on the right track?

Discussion in '40- & 55-Series Tech' started by ken_79-fj40, Aug 3, 2005.

  1. ken_79-fj40

    ken_79-fj40

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    So I have been having a few issues, I believe with my carb. When I start the truck up cold, it starts fine. Let it sit a few hours after driving it, it's tough to start. Sometimes tough to start after about only 10 minutes. It also stumbles quite a bit in first gear until 1500 rpm or so. It's got a weber 38/38 on it.

    So last night I pulled the top off the carb, cleaned out some gunk in the bowl, pulled the two top air jets and the bottom jets, as well as the two that go into the sides of the carb at the top. Cleaned them all out good with carb cleaner and air. Also took off the accelerator pump , everything looked ok to me there. I also took off and cleaned the spraybar thingy that hovers over the top of each barrel of the carb. Put it all back together, everything nice and clean. Runs better, but still stumbles in 1st. So I dial my adjustable ultra high quality napa fuel pressure regulator from 3 to 4.5 pounds. Gets better, but still there. Took it off entirely, runs better, but still a slight stumble. And cruising around the neighborhood in 2cnd at 1100 rpm or so, floor it and it pops and sputters. I'm thinking maybe my accelerator pump is actually on it's way out? I'm also trying to figure out exactly what the point gap and dwell is supposed to be on my mallory single point distributor. I'm suspecting that also.
     
  2. jjhancock

    jjhancock

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    I have an Aisin, but I had almost the exact same problems. Sputtering and hesitating at certain rpm ranges, and even sometimes when you put the pedal down. I also noticed it being worse at cruising speed of 45 mph on very hot days. Jim C said it was likely my accelerator pump not functioning correctly. I don't know much about webers specifically though...

    I did plugs, plug wires, dizzy cap, rotor, and almost all new vacuum lines in the truck, fuel filter too. I got it boiled down to either the fuel pump or the carb, and my fuel bowl was always full, so I figured it was the carb more than likely. I've since sent it in to Jim C and am waiting to get it back soon.

    Can you check your fuel level? Is there a sight window in the bowl?
     
  3. ken_79-fj40

    ken_79-fj40

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    Replaced the accelerator pump, and re-gapped the points to mallory spec. Starts better now, still stumbles a bit though. But only when I put a load on it under 1500 rpm. If I try and ease away from a stop and give it gas, it just about stalls. Rev it up to 1500 and take off, you would never know there was anything wrong. Talking with a friend last night and I think I may have another possibility. This all started when I changed plugs, points, condensor, and adjusted the valves. I have swapped back to the same plugs as before, regapped the points, changed the condensor, totally cleaned the carb, but I haven't rechecked the valves. And I recall finding the line on the flywheel was a major PITA last time around. I'm wondering if maybe a few valves are a touch too tight, and aren't closing all the way. I would think I would feel a miss all the time with this, but anythings possible on a tractor motor I guess. Anyone else think this is possible.
     
  4. NJFJ40

    NJFJ40

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    I was gonna suggest that the issue about starting it again after running it for a while may be related to boiling off gas in the carb once you shut it down. This is addressed by the Carb cooling fan which should be stock item on your 79. I do not think that would explain the other issues you post though.
    Do you have the carb cooling fan hooked up and operational?


    Have you checked timing lately?

    AndrewT
     
  5. ken_79-fj40

    ken_79-fj40

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    The restarting issue seems to have gone away since I regapped the points and changed the accelerator pump. Last night I went down to the garage 2- 2 1/2 hours after driving it around. Fired right back up. Tonight i'm going to check the points with a dwell meter, recheck the valve adjustment, and cross my fingers. I'm headed on a 3 plus hour one way journey to a truck show in it at 8am tomorrow morning. And unfortunately I don't have a carb fan, it's long gone from p/o hacking. Although up until the last few weeks, I never had an issue.
     
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