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Hard Engine Starting Question

Discussion in 'Early CJ5 and CJ6 Tech' started by Jeepman31, Jul 18, 2017.

  1. Jul 18, 2017
    Jeepman31

    Jeepman31 New Member

    Colorado, USA
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    Jan 19, 2017
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    Hello,

    I'm tackling the next issue on my '70 CJ5 225. It seems that if I have not driven the Jeep for a few days, it takes several rounds of cranking and pumping the gas pedal to get it to start it up again.

    If I drive the Jeep to work, and start it at the end of the day to come home, it fires right up the first time. Or if I drive it the next day, it usually fires right up.

    But if it has been a few days, I have to crank and crank.

    I'm not sure where to start on this, so some suggestions based on your guys' experience would be good. I searched the forum but did not find anything similar to my problem.

    Do you think this is carburetor, fuel pump or ???

    Thank you once again, this forum is the best!
     
  2. Jul 18, 2017
    Twin2

    Twin2 not him 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Virginia Beach, VA
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    I don't drive my jeep very often . so it sits in garage . for weeks at a time sometimes . when I do go out to start it . it may take 3 tries . 15 seconds of cranking the starter for the fuel to make it back up to carburetor . normal
     
  3. Jul 18, 2017
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Choke adjustment/function?
     
  4. Jul 18, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    cordele, Ga.
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    What carb are you using? Does it have a choke? The fuel pump as a flapper valve built into it. If the valve has junk under it fuel will run backwards from the carb fuel line back down over night. The pump has a hard time sucking air but will eventually. The float bowl should retain fuel for a couple a days or so.
     
  5. Jul 18, 2017
    Jeepman31

    Jeepman31 New Member

    Colorado, USA
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    Yes, I have a manual choke. The jeep starts just fine when driven the same day, and the choke seems to be functioning correctly. The carb is the stock 2 jet RP Rochester.

    Is there a way to access and clean that flapper valve in the fuel pump? That sounds like a good place to start.
     
  6. Jul 18, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    This sounds like dry bowl syndrome to me. The bowl can dry out from evaporation, especially if the gaskets are leaky or you have an open element air cleaner. Drain back, maybe, depends on the design of the carburetor. First thing I would do is let the car sit for a couple of weeks, and then pour a teaspoon or two of fuel down the carburetor before I tried to start it. If you have a dry bowl, the car will start immediately.

    Next I'd test the fuel pump. Your TSM should have a pressure spec for fuel delivery, and you can check the flow of fuel from the pump. The pump should deliver a lusty spurt at each engine rotation, and give you a couple of inches of gas in a jelly jar after, say, 10 seconds of cranking. Do this with the coil wire removed, transmission in neutral, and take care not start a fire.

    Do that and tell us how it goes.
     
    cookieman likes this.
  7. Jul 18, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    No. Fuel pump is pretty much a throw-away item. They were rebuildable back in the 40s, but no longer. Test the flow before you condemn the fuel pump.

    I think its more likely that the bowl is drying out from evaporation or worn-out carburetor parts draining the bowl. Have you rebuilt the carburetor since you've owned the Jeep? Do you have an open-element air cleaner? I don't know the RP specifically, but I'm skeptical that it would drain back to the pump. Easy to test - disconnect the fuel pump, plug the line, and see if the bowl stays wet over a week or whatever.
     
  8. Jul 18, 2017
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    :shock::shock::shock:
     
  9. Jul 18, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Too, umm, evocative? :coffee::rofl:
     
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  10. Jul 18, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Dry fuel bowl gets my vote also. Could be the float needs adjusting too.
     
  11. Jul 18, 2017
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    :D
     
  12. Jul 18, 2017
    CJMark

    CJMark Jeeper

    Spearfish, SD
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    I had exact same problem with my '71 CJ5 225 Rochester 2gc, put in carb rebuild kit, fixed problem. The CJ can now set for a week or two, depress accelator to set choke, fires right up. The rebuild kit is an easy, inexpensive fix to an annoying problem.
    Mark
     
  13. Jul 19, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    225V6 fuel pump should pump up to about 3 lbs pressure and hold it there if not leaking back and needle and seat are good with float bowl full. Idle engine for a few minutes then shut it down. Let set for couple of hours then crack open fuel line fitting going into the carb. You should get a spray of fuel releasing the holding pressure. I have removed the in and out lines from the fuel pump and spray carb cleaner into the inlet at the pump and hit it with compressed air. Cleans junk from flapper valve restores operation. A filter between tank and pump will save the pump valve from getting junked up. An in-line pressure gauge will also show any bleed-back if connected between carb and pump.
     
  14. Jul 19, 2017
    Jeepman31

    Jeepman31 New Member

    Colorado, USA
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    All great suggestions, thank you guys. I will try some of these ideas as soon as I get some spare time and check back in with the results.
     
  15. Jul 30, 2017
    Jeepman31

    Jeepman31 New Member

    Colorado, USA
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    Well, I'm really stuck now. In the process of un-threading the larger fuel line fitting that threads into the side of the carb (the piece that the smaller fuel line threads into), the threads pulled right out of the top half of the carb. So now I can't even drive the mess. I do need a fuel pump, pressure is not holding at the carb. But that is the least of my worries. I'm starting to go broke working on this Jeep.

    Any ideas where I can get a new top half of the carb? I ordered a filter from Mike's carb that was supposed to fit my carb, but it did not even fit. So I am not sure if they have anything that would even work. I can't find any numbers or ID on the carb anywhere.

    IMG_0224.JPG

    Any ideas please???
     
  16. Jul 30, 2017
    Twin2

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  17. Jul 30, 2017
    Jeepman31

    Jeepman31 New Member

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    Last edited: Jul 30, 2017
  18. Jul 30, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    You should own one of these - 6 in. Composite Digital Caliper

    Similar inexpensive calipers are available on eBay and at Amazon - Amazon.com: digital caliper

    The size of the wrench you use on the nut is probably the least useful measurement you can make. The tubing size should be 5/16". That's the 5/16" that the product listing is referring to. The 7/8" measurement is the nominal ID of the hole in the carburetor, or the nominal outside measurement of the threaded part that goes into the carburetor.

    This part is also available from Amazon Amazon.com: Dorman HELP! 55125 Carburetor Fuel Inlet Fitting: Automotive and if you have Prime, no charge for shipping. Amazon has a very liberal return policy - if it's not suitable, you can return it.
     
    Last edited: Jul 30, 2017
  19. Jul 30, 2017
    Jeepman31

    Jeepman31 New Member

    Colorado, USA
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  20. Jul 30, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The wrench size is irrelevant. If you want to measure the threaded part, you count the nuber of threads per inch, the diameter of the threaded part, and whether the threads are straight or tapered (pipe thread). Yes, the 5/16" OD tube implies a standard size for the flare nut. There are two possible angles for the flare, 45 degrees (SAE, Society of Automotive Engineers) or 37 degrees (AN, Army-Navy). This is an SAE fitting.

    Possible. This is intended for a Rochester 4V carb, not the 2G. Might be the same as the 55125, might be different. No measurement given for the carburetor side.

    I don't see why this part is any more appealing than the Dorman part. Self tapping means that the fitting will have a slightly larger and tapered thread on the carburetor side. The carburetor material is soft (zinc?), and can be re-threaded by the new fitting. Apparently this is a common problem, since there is a readily available part that fixes the issue.

    Dorman offers other sizes:
    Dorman Products - 55140
    Dorman Products - 55124

    Measure your fitting and carburetor and pick the one with the right size.
     
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