old truck puzzler...

Discussion in 'Bad Dog Cafe' started by getbent, Mar 24, 2013.

  1. getbent

    getbent Telefied Silver Supporter

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    okay, my 16 year old son has been having a blast with the old truck that we put together (a 1967 Jeep pickup)....

    I've put a ton of hours and some money into getting her running well, I'm not done by a long stretch.. but, she is road worthy and he is driving it everyday to school and around the local hills and lots of stuff I'm sure I don't want to see (i think donuts aren't just for dunkin) after baseball practice in the field where they park...

    So, he has some symptoms that I'm about to dive in on and would love to hear from you car mechanic types!

    He is experiencing some power loss after a few minutes at highway speeds, then it surges back and then kind of goes back and forth.... occasionally during one of the dropoffs in power, the truck will actually die.

    He puts it in neutral, restarts the truck and it fires right up and when he puts it in drive, away he goes again.

    When just driving home to school and in town.. no issues.

    What has already been done
    1) new carburetor (had it specially built as it was hard to find the OEM part, went to a guru and the truck has been running for 6 months without any of these symptoms.)
    2) All new fuel lines
    3) New fuel tank
    4) new fuel pump
    5) new fuel tank and pickup

    My first plan:
    I need to teach him how to change and lube the truck fully.. and since summer is around the corner, we're going to flush the radiator, change oil and filter, lube the chassis AND change the transmission fluid and install new screen.

    (I suspect his oil pickup is also not working properly, but that is a separate problem and common on the old Kaiser 327 engine)

    I had a similar issue with an old chevy truck I had years ago and just by changing the transmission filter/screen... the surging issue disappeared, so, it is a cheap and easy solution and a good thing to try. The tranny is a TH-400...

    After the fluids are fully replaced, we'll give it a test drive and see if we still have the problem. I'm kind of thinking of using the tractor version of transmission fluid on this truck... it has a tendency to tighten things up which also may be helpful.

    Okay, I'm open to suggestions before going to the transmission guys...

    and if you have suggestions for resolving the oil pickup not generating enough pickup, I'd love to hear them!
     
  2. chuck_zc

    chuck_zc Tele-Meister

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    loosen the fuel cap a bit and try it again
     
  3. Pup Tentacle

    Pup Tentacle Tele-Holic

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    Could be vapor lock.
     
  4. dsutton24

    dsutton24 Doctor of Teleocity Ad Free Member

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    Exhaust restriction?
     
  5. tfsails

    tfsails Friend of Leo's

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    Maybe you need a new fuel filter. I had a car one time that wouldn't go much faster than idle and a new filter fixed it. My problem was not intermittent, though.
     
  6. getbent

    getbent Telefied Silver Supporter

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    these are all great suggestions, thanks guys!

    used to get vapor lock on my rv (ford 460 engine)

    I have heard of the gas cap trick, and I had to build the gas filler and it is tight (in terms of the connections are tight although I did put a bung in the neck for airflow to and from the tank, I'll check it.
     
  7. dented

    dented Doctor of Teleocity

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    I was thinking a vacuum problem. But I have never worked on that engine even though we had one. We had a '68. It had many carb problems if I remember correctly. It was my Dad's and he wouldn't let me touch it. Hmmmm, come to think of it, I got nothin' for ya.
     
  8. Obsessed

    Obsessed Telefied Silver Supporter

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    Yep, as chuck_zc suggests, it might be a gas tank breather clogged.

    #2 I'd check fuel filter leading to carb. Maybe that gas tank had some old stuff in it.
    #3 Check stone filter at Carb fuel inlet.
    #4 Check float bowl height adjustment.
    #5 Check spark plugs.
     
  9. emu!

    emu! Poster Extraordinaire

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    agree...something with the fuel situation.

    Maybe the choke is getting stuck.
     
  10. muchxs

    muchxs Doctor of Teleocity

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    Float level in that fancy carb ain't right. Try raising the float level.

    It's starving for fuel one way or another.

    I'd make an adapter out of 1/4" aluminum or phenolic just 'cuz I don't like to buy anything I can make. I'd stick an old Rochester carb off a '60s or '70s Chevy on there. Any two barrel carb off any old Chevy will do. Don't even jet it. They're usually jetted pre- smog super rich.

    If it still don't run right blow out the fuel line between the tank and fuel pump with compressed air.

    No one knows anything about carburetors anymore.

    The expensive solution:

    Track down a Zenith 32NDIX carb off a Mercedes Unimog. It's the best off road carb you can buy. You can feed it mostly dirt with a little gas, it will still work. The bad news... they're stupid expensive because they don't make them anymore and they came on some '60s Porsches.
     
  11. Tim Armstrong

    Tim Armstrong Super Moderator Ad Free Member

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    I agree it sure sounds like a fuel issue, but will note that I had a 1975 International Scout II that had similar problems, and my mechanic eventually figured out that I had a faulty coil. Replaced it and it was a whole new (and much better) ballgame.
     
  12. pchilson

    pchilson Friend of Leo's

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    If the fuel tank has been removed and replaced make sure there is no kinking in any of the fuel lines. I had this happen before. Around town (lower speeds) fuel delivery was sufficeint but at highway speed it would starve out after a couple miles.
     
  13. dutchgoff

    dutchgoff Tele-Holic

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    I think it is one of two things. I agree with Tim on the ignition side especially if it is a points ignition. If it is I would look at the condenser overheating. The other thing I think would be a very good prospect is a vacuum loss, not uncommon on older jeeps. Before I spent much time or money I would install a vacuum Gage and a fuel pressure Gage. Run them into the cab where you can read them when it happens and see what they tell you. It could save you a lot of trial and error, headache, busted knuckles, cursing and other such mechanical atrocities.
     
  14. Toto'sDad

    Toto'sDad Tele Axpert Ad Free Member

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    You mentioned you had replaced all the fuel lines. I had a ford pickup doing what appears to be the same thing. One day I very carefully checked my fuel lines and a small piece of hose that connected two steel lines was positioned so that when the fuel was flowing at the maximum rate it would suck the hose together and shut off the fuel. When the engine would die, after the truck sat for a little while the hose would relax, fuel would flow, it would start back up and run for a while then go through the whole routine again.
     
  15. fezz parka

    fezz parka ---------------------------

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    What Tim said. Check the coil and wiring to the coil. The old '59 used to do exactly what you are describing, and it was an intermittent connection to the coil.
     
  16. garytelecastor

    garytelecastor Poster Extraordinaire

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    I have a Buick that had the same problem. It was the cam shaft sensor.

    It also sounds like it might be your throttle position sensor.

    What model is the Jeep?
     
  17. Frodebro

    Frodebro Doctor of Teleocity Ad Free Member

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    It's a 1967-no throttle position or cam sensors on that bad boy. It's a motor, a carb, and an old-school ignition system with a coil and points. The only emissions equipment you'll find is positive crankcase ventilation.
     
  18. getbent

    getbent Telefied Silver Supporter

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    this is awesome fellers! I'm making a big list... he'll drive it all this week, but I have friday free and we are gonna work through each suggestion...

    once this is fixed... he wants a lift kit and some pizza cutters!
     
  19. telleutelleme

    telleutelleme Telefied Silver Supporter

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    Gas cap breather if it is the original.

    Sounds like vapor lock. As a test use the old clothespin method to isolate. Place several wood clothespins on the metal line running from the carburetor to the fuel pump. They act as heat sinks and draw heat out of the hose which help keep the line from getting too hot and vapor locking. If the problem goes away you need to find out what is causing the line to get too hot. Probably routed wrong.
     
  20. JCSouthpawtele

    JCSouthpawtele Friend of Leo's

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    If it seems to die on inclines or decent in the hills or on corners its the fuel flow in the float bowls of the carb. Maybe the carb needs rebuilt. Those needle get gummy with fuel if it sat for a period of time. A friend rebuilds old carbs for a hobby and gets a lot of vintage hotrod guys buying his stuff on eBay.
     
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