Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 

Thread: vapor lock 454
          
   
   

Reply To Thread
Results 1 to 9 of 9
  1. #1
    grifo7's Avatar
    grifo7 is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2006
    Location
    Twickenham
    Car Year, Make, Model: 68 Iso Grifo 7 Liter,
    Posts
    62

    vapor lock 454

     



    Hi guys,
    I'm hoping someone can advise me how to cure a problem I've had recently. Last weekend I was driving my 68 Iso Grifo (454 BBC engine) home from the Silverstone Classic in the UK. I'd been sitting on about 80mph for about 45 mins on the freeway, when I felt the engine jerk a couple of times. It happened again a couple more times, then the motor cut completely and I pulled over. There was no fuel visible in the glass filter on the fuel line and no pressure at all on the gauge just before the Holley carb. I could hear the fuel pump (Holley 125 electric) was working when I switched on the ignition. When things cooled down a bit, I tried again, fuel gushed back into the carb and she started right up again. When I got home and had been in traffic for a while I looked again under the hood and saw that there was very low fuel pressure and the glass filter was only partly full, so I'm sure the motor would have quit again fairly soon.

    I guess this is a vapor lock situation - what should I do? I suppose the fuel line from the tank must run too close to the exhaust somewhere. The pump is back near the tank, so if the problem is between the pump and engine, why doesn't the pump just push more fuel through? I guess the way to go is to lag the whole fuel line with heat insulating sleeving? Any recommendations on products? Should I wrap up the pump in heat shielding too?

    Your thoughts would be appreciated!

    Thanks,
    Chris

  2. #2
    robot's Avatar
    robot is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2004
    Location
    Tucson
    Car Year, Make, Model: 39 Ford Coupe, 32 Ford Roadster
    Posts
    2,334

    ISOs are cool cars....dont see many in the US anymore

    If you have an electric pump, it should be mounted as close
    to the petrol (see, we can talk Engrish over here) so that the
    pump is pushing fuel. Electric pumps are poor at pulling fuel.

    How far from the tank outlet to the pump? Since the electric pump
    is pushing, the fuel should not vapor lock. However, the line
    from the tank to the pump could vapor lock....the pump doesnt
    have enough suck to pull out of the condition until all cool down.

    Another idea is the pump getting weak OR you are getting a
    low voltage condition to the pump that is caused by heat.

    mike in tucson

  3. #3
    grifo7's Avatar
    grifo7 is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2006
    Location
    Twickenham
    Car Year, Make, Model: 68 Iso Grifo 7 Liter,
    Posts
    62

    Thanks, Mike.
    The pump is brand new and is pretty close to the tank. It is fairly near one of the 3" pipes and its muffler. I will look at lagging everything on the tank side of the pump, and will probably do everything forward to the carb - can't hurt, after all.
    Chris

  4. #4
    Mikej's Avatar
    Mikej is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2004
    Location
    Portsmouth
    Car Year, Make, Model: 1935 Chevy Master Sport Coupe
    Posts
    98

    Are you having the same heat wave as europe and russia? Under hood temps maybe higher than normal for you, but moving the fuel lines or insulating may help. Or a regulator and a return to the gas tank to keep the fuel moving.
    If it's not broke, fix it anyway.

  5. #5
    robot's Avatar
    robot is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2004
    Location
    Tucson
    Car Year, Make, Model: 39 Ford Coupe, 32 Ford Roadster
    Posts
    2,334

    Just as a test, you could take some insulation (like house insulation)
    and wrap it around the fuel line where you think it is exposed to higher
    heat. Use some alumninum foil wrapped around the insulation to secure
    it....dont compress the insulation too much. That will be a quick experiment
    to see if it is heat in a particular spot


    another thought...is there a particularly long run of rubber hose in
    the system? Rubber hoses should not be longer than perhaps a couple
    of feet (British feet is OK). Long runs should be metallic line, never copper.


    mike in tucson

  6. #6
    skids72's Avatar
    skids72 is offline CHR Member Visit my Photo Gallery
    Join Date
    Dec 2005
    Location
    Lafayette
    Car Year, Make, Model: 68 Firebird 439 BBC
    Posts
    745

    Quote Originally Posted by Mikej View Post
    ...Or a regulator and a return to the gas tank to keep the fuel moving.
    ^^^this is how I solved this problem with mine... insulating the lines helped to a degree but didn't completely solve it until installing bypass regulator with return to the tank... the cause in my car was poor air circulation in the engine compartment likely due to the absence of inner fender wells but this often happens when fuel line close to exhaust as you described... start with sleeving the line in that area (I use the orange sleeve heat shield material, I don't know what it's called). If you continue to have problems, a bypass regulator will fix it for good.

    -Chris
    Last edited by skids72; 08-01-2010 at 12:03 PM.
    Paint don't make it no faster

  7. #7
    grifo7's Avatar
    grifo7 is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2006
    Location
    Twickenham
    Car Year, Make, Model: 68 Iso Grifo 7 Liter,
    Posts
    62

    Thanks, guys - this is all incredibly helpful. I've read about fuel return lines. Can anyone describe what the layout is, and what hardware I would need? My pump is a Holley 125 electric (gerotor pump, like some oil pumps and nice and quiet). It is internally regulated at about 7psi.
    Thanks,
    Chris

  8. #8
    Dave Severson is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Jul 2003
    Location
    Madison
    Car Year, Make, Model: '67 Ranchero, '57 Chevy, '82 Camaro,
    Posts
    21,160

    You'll need a regulator with a return port on it, then route a 5/16" line from the return port back to your tank, works fine if the return line goes into the top of the tank... Also make sure the line from the regulator to the carb is away and or insulated from high heat sources, too...
    Yesterday is history, tomorrow is a mystery, Live for Today!
    Carroll Shelby

    Learning must be difficult for those who already know it all!!!!

  9. #9
    rumrumm's Avatar
    rumrumm is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2004
    Location
    Macomb
    Car Year, Make, Model: '32 Ford 3W Coupe, 383 sbc
    Posts
    1,593

    Holley pumps run hot if you do not use a return line, and over time they will fail because of it.


    Lynn
    '32 3W

    There's no 12 step program for stupid!

    http://photo.net/photos/Lynn%20Johanson

Reply To Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink