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vapor lock, or something like it...

Discussion in '40- & 55-Series Tech' started by swank60, Mar 6, 2003.

  1. swank60

    swank60

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    Does anyone know exactly where the fuel tank vents are on an FJ60? I'm having a negative fuel flow problem and I'm guessing the tank isn't breathing the way it should...well, that, and I can actually hear the tank suck gas back into it when I shut the engine off.
     
  2. bernefj60

    bernefj60

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    I suspect that one of two things is happening:

    A. Your charcoal canister is failing.

    B. you have gotten what's commonly know as "schmutz" into you fuel lines.

    I would bet on A. Check it. No doubt the lines are cracked, the bottom is rusted out, and the fuel smell you're not mentioning is strongest right above it. Oh, and replace your fuel filter.

    hth

    Rob
     
  3. swank60

    swank60

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    See, that's the weird part - there isn't a pronounced gas smell anywhere...

    I'll check the canister...

    Thanks!
     
  4. bernefj60

    bernefj60

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    now i am suprised. If you had a problem with the tank venting, you'd definitely smell it in the cab as the vent filter apparatus is interior to the vehicle. (it's in the back behind the PS kick panel.)

    Let me know what you find. Often the canisters wil get gummed up and, becasue it's a sealed system, you'll have delivery problems.

    don't rule out the fuel pump, though. That'd be the first thing i replaced.

    Rob
     
  5. swank60

    swank60

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    Okay, I checked the canister, and when I pulled the line that comes from the tank, gas started coming out of it - not a ton - maybe 1/2 a teaspoon full. It also started making, what seemed to be, a sucking sound (as opposed to blowing) - I went back to the gas cap and opened it, and the sucking from the hose at the canister stopped.

    So how weird is that? I don't know. But the whole thing seems to be causing a real vapor lock situation, too. I was driving it around today, and after I stopped, I raised the hood and looked in at the carb's glass eye - guess what? the gasoline in it was bubbling around and disappearing.

    See, what the main delima is, when I try to start it after it's been sitting for a while - more than four hours or so - I can't unless I pull full choke, then, raise the hood, and clamp the choke the rest of the way closed with needle-nosed vise grips. I have to leave the choke on for a little while, then it runs fine.

    When it's hot, and I stop for more than a couple of minutes, it's harder than :eek: to start.

    That's why I think the fuel pump is okay. I plan on checking the vents on it to see if they are clogged too.

    One other thing - I have undercoadted the bottom of the truck with that rubberized stuff in a rattle can - is there a chance I plugged something up?
     
  6. bernefj60

    bernefj60

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    How are your fuel lines run? Is it especially hot where you are? Could it be that your float is sticking?

    What you're describing does sound like vapor lock, but it also sound like a fuel pump going bad. Having had it happen to me twice, i can tell you if it surges when you're driving, it's a fuel pump.

    Undercoating shouldn't have affected anything.

    i'll give it some more thought. Meanwhile, check to see that your lines as they comes across the front of your motor aren't getting too hot.

    Rob
     
  7. swank60

    swank60

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    My fuel lines are all stock, from the factory, but I live in Texas, and it does get pretty warm. We just went through a cold spell and although I still had problems getting it started from cold, there was little problem starting it after it had warmed up. Go figure though, it was in the low 30s.

    I changed the fuel filter yesterday, and I'll see if that does any good, and I'm shopping for a new fuel pump, too (but I'm not getting any weirdness when I drive - engine is smooth, accelerates smooth, etc). I'll check the float sometime over the weekend too, but I don't think it's sticking. (Last weekend I dumped half a bottle of Marvel Mystery Oil down the throat of the carb, and had the fuel pump pull the rest of the bottle into the carb and let is soak for a while...)

    I'm also going to check that vent in the back, and blow out all of the lines to see if that helps.

    Thanks for all of your help, by the way. It's much appreciated.
     
  8. swank60

    swank60

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    I went through most of the basics, but I found a "fix" that probably points to the fuel pump as being my culprit.

    I found a vent line to the tank and blew compressed air into it (to pressurize the tank) - which gave a pozitive fuel flow into the carb...no more vapor lock, temp flux, easy starting, etc. All the vents were clear, and I feel confident that the tank is breathing fine...and it doesn't seem to hold the pressure overnight.

    I'm going to call around today and see what I can do for the fuel pump - I'm betting that's it.
     
  9. woody

    woody Internet Fireman Staff Member

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    The vapor dealie on a FJ40 has a drain tube....notorious for clogging with rust. Make sure you didn't undercoat it shut, if the 60's have it....
     
  10. swank60

    swank60

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    No luck.

    I put a new fuel pump in, I've check all of the lines, I've poured a ton of different solvents into the carb and though I don't have the problem with the gas being sucked back into the tank anymore, it still won't start from cold (without closing the choke completly - and I mean getting out, raising the hood and clamping it fully closed) - and the temp. still goes way up and it won't start once it's warmed up either.

    I looked for any clogging near the tank, too, and there's nothing blocked.

    What the hell is my next option? I can't afford to take this thing it to the local "Land Cruiser" mechanic. WTF?

    Do I need to rebuild the carb now? Is that going to do me any good?
     
  11. kruzrtek

    kruzrtek

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    You didn't try to drive it or run it with the fuel filler cap off did you? That may help the venting. Oh, and when you say you open the hood and pinch the choke off completely, what are you referring to exactly?
     
  12. 3_puppies

    3_puppies SILVER Star

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    This sounds funny but it happened to a friend of mine. Are the fuel lines original/old? My friend had a small crack in one the rubber lines, it was small enough to let air in but not show any signs of a fuel leak. The lines looked good in the rig and was only found after removing the lines and getting a good visual and being able to flex the lines.
     
  13. swank60

    swank60

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    I have run it with the fuel cap loose, and that was helping with the fuel vaccum issue, but it still doesn't get gas at first start or when it's just been running. (If I let it set for 5-15 minutes, it's hard starting, if it sets for 30 minutes up to an hour, it starts fine - over 4 hours and it's like a cold start, and I have to go through the choke senario again - in winter - summer the time span is longer)

    What I do with the choke is: there is a bar on the left side of the carb that links directly to the choke, behind it, there is a flat plate - I'm not sure where it is attached...anyway, at full choke, I go out with a pair of needle nose vise grips and clamp the choke linkage to that flat plate, which closes off the choke plate (visible when you have the breather off, it's over the right-side carb barrel) That gets it started and I have to run it with the choke on, no matter the weather, for about 5-10 minutes.

    I'm checking the accelerator pump today some time to see if it's working properly, and I'm not sure if my float is sticking or not. I've been noticing the level in the glass eye of the carb has been changing - sometimes it looks too low, other times it's filled up completly...sometimes it's bubbling (vapor lock)

    On the cracked fuel line issue - where did your friend fine the cracked fuel line? Was it close to the tank or the carb? That would make sense because it's like there's no fuel in the line after it sets for a while. Also, if I blow compressed air into the tank through one of the smaller vent lines and pressurize the tank, it helps with the cold starting and it doens't vapor lock.

    This sort of thing is putting me at wits end (and I didn't have far to go in the first place...)
     
  14. kruzrtek

    kruzrtek

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    It does sound a little like the accelerator pump and needle, seat =, and float assembly may be causing some problem. But you might want to try one thing before you dig in. On the side of the float bowl, opposite of the fuel line coming in, there is a hose on the top of the carb, sould be approx. 3/8" hose.
    This vent the vapors from the float bowl to the charcoal canister. If you clamp this line off with your needle nose vise gips or remove it and cap the port it came off of. This sometimes helps with the problem of no fuel in the carb or lines. What happens is the charcoal canister basically overworks and eats all the fuel vapors and then there is no fuel left ine the lines or float bowl and you have to crank with the choke on to "siphon" fuel up to the carb. You may have
    a different problem, but it may be worth a try.
    If nothing else you can do this when all is well and you will have fuel in the carb at all times, instead of cranking it for a while.

    Kruzrtek
     
  15. swank60

    swank60

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    Well, I tried blocking off that vapor bleed off hose and it was a no-go. I looked down the throat of the carb and pumped the throttle a few times and there was no gas spraying into the carb at all.

    Great.

    I tried the "chemical rebuild" - dumped Marvel Mystery Oil into the float bowl, let it soak, etc...didn't do any good.

    I've rebuilt side-draft carbs for the Triumph - is the Toyota carb going to be a total nightmare to rebuild?