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Summer heat is on, now I am vapor locking...

Discussion in 'The Hokey Ass Message Board' started by t-town-track-t, Jul 21, 2010.

  1. t-town-track-t
    Joined: Jan 11, 2006
    Posts: 884

    from Tulsa

    ok, so twice last week, now that we are above 95 degrees with 150% humidity, I have had vapor lock issues.

    I'm talking about my 54 Bel Air, 235 - power glide. Bone stock.

    The first time I let the car cool for a few hours and then it started right back up.

    The second time, I was able to pour enough cool water over the fuel lines to get the fuel to condense and re-prime the pump.

    So off to Home depot I went and bought some of that high density HVAC copper line insulation stuff. It looked like hell under the hood, but since this is my daily driver, I did not care. Function is more important than looking good. This seemed to fix the problem for a few days.

    So today I went to lunch and sat inside for nearly 45 minutes, came out, and sure enough, vapor locked. Yanked the insulation off, and cooled the lines off with water again, got me back on the road. Then tonight while I sat in line for 10-12 minutes waiting on some chinese food, it vapor locked while idling in the parking lot. I am a little bit pissed off at this point.

    Here in Oklahoma we have been blessed with 10% ethanol, as most of the rest of you have. I would assume that ethanol has a lower vapor point than gasoline? So that is probably part of my issue. So besides spending more money, and being inconvenienced with locations that sell straight gasoline, what options do I have?

    I know that lengths of rubber fuel line can make the problem worse. But in my case, everything under the hood is stock, and the fuel line is hard lined from the tank, through the pump, all the way to the carb.

    Anyone have any creative suggestions?

    I'm not crazy about having to pour a gallon of water on the fuel lines every time I want to go somewhere.
  2. dana barlow
    Joined: May 30, 2006
    Posts: 3,957

    dana barlow
    from Miami Fla.
    1. Y-blocks

    Alum tinfoil seem to work,plus a few extra gastkets under the carb,in extream heat,when parked,open hood some.
  3. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    from Phoenix AZ

    Yes I feel your pain !! Just had to re-engineer the fuel supply on my T . Went from a top feed out of the tank to a bottom feed, seems to have solved the prob for me. This modern fuel is so volatile that it goes to vapor state with the least provocation. Had the same prob 2 years ago on my 65 Ranchero when the temp hit 100 it was unusable. The fix there was to add a return line from near the carb back to the tank. The continual fuel flow kept the fuel in the lines cooler and WOW no more vapor lock. I used a small in-line metal body fuel filter with a 3 rd line for the return back to the tank filler neck. This filter was off a Mopar app. Still working good as the temps here in Phoenix have been 110-117 for the last several weeks. ElPolaco did a similar deal for a guy travling through several years ago and fixed him up also.
  4. Angel of Sin
    Joined: Apr 29, 2010
    Posts: 35

    Angel of Sin

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  5. Brad54
    Joined: Apr 15, 2004
    Posts: 6,008

    from Atl Ga

    Do you have a chrome coil?

    I've seen a failing coil cause this EXACT problem. When air stops moving through the engine compartment (like when you're idling or driving slow), the coil overheats and quits. It takes about the same amount of time for the coil to cool as it takes to cool the fuel lines with water.

    Chrome coils are the worst, because the chrome reflects heat back into the coil, while black sheds the heat to the air.

  6. t-town-track-t
    Joined: Jan 11, 2006
    Posts: 884

    from Tulsa

    My coil is a plain old school black coil. I know it is the fuel issue for sure. I have a clear plastic fuel filter about 8" in front of the carb. When it is VL'd I can see nothing pumping through it. As soon as I pour cold water on the fuel lines, and crank, I can see fuel pulsing through the filter as it should be.
  7. claymore
    Joined: Feb 21, 2009
    Posts: 896


    Simple solution add an electric fuel pump.
  8. skwurl
    Joined: Aug 25, 2008
    Posts: 1,620


    It seems to me that six bangers are the worst for this too. My rambler does it every now and then. I was thinking of possibly a carb spacer. To sepeate it from the manifold a bit more
  9. I was thinking what Claymore said ... install a "pusher" electric fuel pump near the tank. Might also help to add a return line at the same time.
  10. OldBuzzard
    Joined: Mar 8, 2008
    Posts: 878


    How old is your fuel pump? Is it allowing the fuel to leak back to tank level which lets the vapor form?
  11. brad chevy
    Joined: Nov 22, 2009
    Posts: 2,627

    brad chevy

    Back in the 60s alot of guys would do the clothspin deal and for some reason it worked,but the best way to cure the problem was by putting a coolcan on it especially the older Mopars.We made ours out of gallon cans with about 8 to 10 coils in the line,if available,we used dryice but mostly just regular ice.I know some of the older Hambers have done this before.Todays gas with the crap ethanol is some problem causing crap,don"t leave any in anything for along period of time ,on yardwork weedeaters and mowers it actually eats holes in fuel lines.
  12. Bigchuck
    Joined: Oct 23, 2007
    Posts: 1,139

    from Austin, TX

    I see lots of posts on this and other car sights about vapor locking. Every car I've ever owned has had a carburetor and I have never had a vapor lock issue. That is living in places where it is always hot in the summer. So, am I just lucky?
  13. rayford
    Joined: Jul 3, 2008
    Posts: 1,238

    from calhoun ga

    ok you might think this is the stupidest thing you have heard but it works wooden cloths pins on the fuel line will stop it from vapor locking you will only need 6 or so they will pull the heat out cheap easy fix
  14. imnezrider
    Joined: Apr 27, 2010
    Posts: 199


    I say no...your car is just operating as designed. As a kid in the hottest part of Texas, I drove my '40 Ford and '51 Chevy with NO problems. I say if you have proper fuel pressure (stock), sufficient fuel volume (stock) and properly operating ignition system, all will be good.
  15. low-n-slo54
    Joined: Jul 25, 2009
    Posts: 1,920


    Also check your heat riser. It's under the carb and may be stuck closed. Mine was doing this so I went ahead and replaced the fuel lines, pump, rebuilt the carb, replaced the base gasket, added an inline fuel filter, and cleaned the tank. 300+ miles and no problems.

    Vapor lock is pretty common.

    As you track down the heat sources, keep in mind that the fuel that flows very slowly thru the fuel lines will pick up heat at every place the fuel line is not exposed to free flowing air and is exposed to warm engine parts, or is exposed to HOT air from heat-radiating parts. That includes not only engine area, but also farther back where an exhaust pipe may run close by, or a hot-air escape path sometimes between frame rails.

    That means the old recommended method of wrapping a spring or other coiled wire around the fuel line will help only in the cooler-air areas to help get rid of heat. Do NOT use that method near the hot areas or you will pick up more heat.

    The old trick of clothes pins, or wrapping the fuel line, or slipping a length of slit-open rubber fuel line over the metal line will work near hotspots or hot radiator air where you pick up more heat, but do not use that insulating method near cool-air areas, since you want the use the cool air exposure to remove heat from the line.

    An electric fuel pump near the rear is a good way to reduce boiling because there is less suction line (suction invites boiling- lower boiling point), and more fuel line under pressure (raises boiling point slightly), but the best thing to do is to keep the fuel recirculating instead of just sitting in the fuel line waiting to slowly move forward to the carb, all the while soaking up more heat.

    Here is a copy of a post I made in a different thread about percolating carbs.
    It has info on what worked very well for me.

    ************************************************** *

    What I did for my Stude pickup when it kept boiling the carb was to turn off the electric pump as I approached a parking lot or driveway before I came to a stop, so the carb wouldn't be full.

    After I got tired of that, or tired of hard starting when I forgot to turn the pump off early, was to buy a fuel filter I used to see on AMC's and other smog-carbed cars of the early 80's.
    Many of them, if not most makes of cars, used what looked like an ordinary fuel filter with an extra outlet.

    That extra outlet is for a fuel return line that runs back to the tank.
    The reason for most vapor-lock (also helps with most carb boiling probs), is that the fuel inches it's way along inside the fuel line, picking up more and more heat as it slowly crawls along. By the time it reaches the carb it is either boiling or very close to it.
    Adding the filter with the built in tiny orifice and return line will keep the fuel moving along, the hot fuel will return to the tank for cooling, and cooler fuel will replace it in the lines near the carb.
    That usually keeps slow moving fuel from just sitting there collecting heat.

    I used to see those filters hanging on the racks with the "normal" filters at Wal Mart Ace Napa and everywhere.

    If they are no longer as common as they used to be, just go to the parts counter, tell them you drive a "1977 PACER" and need a fuel filter.

    I don't know if ALL the filters will have the tiny orifice in the return outlet to keep you from starving the carb, but the AMC ones certainly did. If yours doesn't have a restrictor orifice built in, you may dump too much fuel pressure back to the tank, and have to restrict your return line in order to feed the carb, but every one of the AMC fuel filters I have used were just right.

    Here are some pics of what they usually looked like, so you can know when you find one.





    Just make sure the return line isn't too free-flowing or you could starve the carb. All the ones I have used have had the restrictor built into the small extra-outlet. I just can't assure you that ALL of them use one.
    The ones I have seen on factory AMC cars have all been mounted not too far from the carb. If you mount them too far back in the fuel system, it will defeat the purpose of keeping the fuel cool at the carb.

    P.S. This style of filter and recirc flow, will only work when mounted after the pump, on the pressure (output) side of it. The closer you mount the recirculating filter to the front near the carb, the less hot fuel you will have in the system.

    Last edited: Jul 22, 2010
  17. I had that same problem driving from OK to Tx past june. Other than that I drive all around town locally with no problems. I have heard the clothespin trick as well, good luck I'll stay posted to see what happens.
  18. BJR
    Joined: Mar 11, 2005
    Posts: 6,389


    As said before, try a new fuel pump, an old one may not be up to the task. Check the heat riser, it may be stuck closed. Check the timing and the advance mechanism in the distributor, it may be stuck retarded or you may have broken/missing springs. The last thing I can think of is a blocked vent on the gas cap, or a non vented cap being used where a vented one is supposed to be. Let us know what fixes it please.
  19. wildearp
    Joined: Oct 24, 2007
    Posts: 522

    from tucson, az

    I thought vapor lock was something that happened to everyone else.......until it happened to me. I had an electric fuel pump mounted near the tank. My issue was caused by percolation of fuel in the carb. I had to add a phenolic heat isolator onto the carb base to eliminate it. Be sure your carb vents are not clogged. A friend also had it happen with an electric fuel pump and it would vapor lock while running down the road.

    A long time ago a bad condensor cost me a lot of heartache. Symptoms were exactly like vapor lock. A brand new condensor too. Always buy Blue Streak!
  20. 6inarow
    Joined: Jan 24, 2007
    Posts: 2,234


    the biggest source of heat is probably the exhaust. Might consider either ceramic coating the exhaust or switching to duals and then ceramic coating them.

    hey, if nothing else its a good excuse to buy headers if you don't already have them.

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