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Hard Start 72 FJ40. Could use some guidance

Discussion in '40- & 55-Series Tech' started by Robert Seiboth, Nov 14, 2017 at 8:21 AM.

  1. Robert Seiboth

    Robert Seiboth SILVER Star

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    So, my early (April) 1972 FJ40 has a hard start issue and would appreciate some guidance for next steps. Short problem explanation is: I have to crank the engine excessively, 8 to 12 times or more, for 10 to 15 seconds each before I get a little ‘rump-rump; and again several more times before it will actually start; or maybe start. This is with the choke pulled out. Once it does start it runs pretty well. Maybe a little white smoke for a minute or less while warming up but that’s it. Odd thing to me is that if I drop a little gas directly into the carb, even if the truck has sat for several days, it starts up almost immediately. I thought maybe a potentially bad (45 year old) fuel pump might be the issue so disconnected the fuel line at the carb and hosed it into a bucket and it’s dumping plenty of clean fuel. I’m leaning toward this being an idle solenoid issue but my carb knowledge is weak. It clicks if I apply 12v and assumed it was working but maybe not. Its literally like something is stopping the flow of fuel with the key on 'start', but not when on 'run'. Not sure what else I can do to check and can’t seem to find one online to replace it short of buying a whole used carb.

    The carb is stock and according to pictures I’ve seen is the correct one for an early 72. Fuel is new and premium grade. The vacuum checks out good, could find no leaks and ~17+ at 625 rpm idle, timing done with a light is ~ 10 degrees (ball near the bottom of the window and sounds good by ear too) which was recommended somewhere when using the Pertronix II with the stock vacuum retard dizzy, plugs gapped right, wires good, and like I said, it runs good with no hesitation on acceleration and smooth idle when I do get it started. If it sits for an hour or so after running, it will re-start with little effort. Sitting over night or after a few days I’m back to cranking…

    Carbs have always confused / scared me, but am figuring this is what I should be focused on at this point? Don’t know where else to look but totally unsure how to test it further. Any suggestions appreciated.


    Bob
     
  2. 1MOA

    1MOA SILVER Star

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    Sounds like your accelerator pump. It's not that it unclogs or works better when it is warm. it is that fuel atomizes much better when it is warm. I would clean the carb well, if it continues after that rebuild the carb.
     
  3. thebigredrocker

    thebigredrocker SILVER Star

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    Next time you get it running, shine a light into the primary side of the carb and look for fuel spray at idle. If you can see fuel spray, that’s an indication the hidden idle fuel delivery port is not doing it’s job. It could be clogged or you could have insufficient vacuum to suck fuel from the idle fuel port.
     
  4. Robert Seiboth

    Robert Seiboth SILVER Star

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    OK, thanks for the suggestion. Needed a shot of carb cleaner (since it still won't start on it's own) but it started OK with a little spray, then I let it warm up, made sure the choke all the way off and there is no spray at idle / about 625 RPM. If I press on the accelerator linkage I can see the mist of spray and it stops as soon as I let go of the linkage. I am still using the Evaporative Emission Control device which seems to divide up or otherwise control the vacuum but I tested the vacuum bypassing it as well (carb to the port directly under the carb, and distributer to the one on top of the manifold) and didn't seem to make any difference in starting or just driving.
     
  5. Robert Seiboth

    Robert Seiboth SILVER Star

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    Also, I did verify the date code on the carb is 2D so the same month (April) and year (1972) as the data plate of the FJ40 so believe this to be the original / correct carb. I have paperwork from the PO the carb was rebuilt / overhauled to the tune of $340 in January of 2013, but was done at a Firestone car care center in ABQ, NM and am not familiar with them.
     
  6. thebigredrocker

    thebigredrocker SILVER Star

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    I’ve read FJ40Jim tell folks with retard type dissy’s to unhook and cap the vacuum port on the distributor. Just run it as a mechanical advance unit.

    My be worth a try to plug, kink or remove the line.
     
  7. Robert Seiboth

    Robert Seiboth SILVER Star

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    I'll give that a shot - also re-read the PO's bill from the carb rebuild; the $340 was just the labour, plus $77 for a carb kit and another $33 for a float - so $450 all-in. ouch...
     
  8. thebigredrocker

    thebigredrocker SILVER Star

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    If you still have the air cleaner off, can you verify the choke plate is actually closing completely when the knob is pulled out?
     
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  9. Robert Seiboth

    Robert Seiboth SILVER Star

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    Wow, thank you - Like I said earlier, carbs confuse me and can't believe it was that simple... Seems the choke plate would never close completely, maybe only 60%. Somehow its getting hung up, tight, maybe just age and grime. The linkage adjusts with the choke cable properly and if its pulled all the way, all I had to do was tap the choke plate a bit and it snapped closed. Started up immediately - The linkage does not move the plate directly, but moves a lever with a slot which allows the choke plate to follow it and assume the wound spring supplies the tension to do that. I cleaned it all a bit and shot some light weight oil on it and 'exercised' it. we'll see what happens... Looks like I can wind that spring one more turn maybe for more tension?

    IMG_3738.png
     
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  10. thebigredrocker

    thebigredrocker SILVER Star

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    Hope you figure out the secret to keep it from binding. WHEN you do, please let me know;)


    If the sticking choke problem persists and you want it fixed, I would bet Mark’s Off Road (65swb45) or TLC Performance(FJ40Jim)
    have figured out a solution. Those guys could also modify your carb base by adding a special port if you want to run a vac advance dizzy.
     
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