#1  
Old 05-23-2023, 08:35 PM
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672brlbaby 672brlbaby is offline
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Default 'Vapor return line question

Have 2 questions.

The vapor return line. The car is a 65 Tempest wagon auto with A/C. Have Edelbrock 4 brl intake/carb. Just put new fuel pump and fuel filter with vapor return line from Ames catalog. With vapor return line in use, the car will run for a few minutes and die. Let it sit for 10 minutes it will start and die again. With vapor return line not used, car runs fantastic. Fuel line has 7pds pressure at carb, but 2pds when vapor line is used. It would seem in the Ames catalog there is only one gas tank sending unit with vapor return line. Can anyone who has had this case tell me how they solved it. Please.

The 2nd question

With the Edelbrock parts, are any lines from the fuel pump to the carb metal, or are they the rubber fuel line?

Thanks for any help.

Jim

  #2  
Old 05-24-2023, 10:20 AM
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pfilean pfilean is offline
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Sounds like a strange problem. I added a return line to my 61 and saw no change in how it ran except I have not had a vapor lock since. Which of course was the point.

Seems like for some reason you are just pumping fuel back through the return line and none to the carb. Are you using a filter with the return provision or a pump with the return provision. The filters have only a pin size hole for the return fuel to go through. I suppose the pumps are the same. That way the full pump volume cannot go back to the tank. Where are you checking pressure? After the filter or between the filter and pump? Where is the return line tapped into the pump output?

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Old 05-24-2023, 11:43 AM
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+2 to above, AND is the vent line to the fuel tank open, and what type of gas cap are you using?

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  #4  
Old 05-24-2023, 06:43 PM
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Thanks for the replies guys, I will try and get pics when I go to the shop on Friday. There is a fuel filter with vapor return and fuel pump with vapor return, from Ames in the last month. Also the sending unit is with vapor return from Ames. I just texted him, and he said there is a vented gas cap. I think he had checked pressure before and after the filter, as it did turn out that that filter was clogged. Hope to update on Friday. Cheers!

Jim

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Old 05-25-2023, 09:21 AM
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There is a vent tube on the filler neck of these cars, so the filler cap should be non vented. You'll need to make sure the vent tube that hooks to the filler neck, and the vent tube in the filler neck are not clogged.

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  #6  
Old 05-25-2023, 09:59 AM
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Why have a vapor return filter AND a vapor return pump. Don't need both. Either one is supposed to do the job. The vapor return pump was an "improvement" from the filter and probably done so when you changed the filter you didn't have to fuss with the return line. The filter was expected to have to be changed more often than the pump.

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Old 05-25-2023, 05:59 PM
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2 new wrinkles in the case. First, with the pressure gauge hooked up after the filter and before the carb, and the car running, and vapor return line connected, gauge reads 2 pds. When the line is clamped off, almost 6 pds.

Second, we believe there should be a non vented cap on the neck. It is vented. No way to tell if the tank is original or ? If it is actually supposed to be non vented, Does any one make a non vented cap to fit on vented neck. Or is there another, orrect tank in my future? or other solution.. Thanks.

Jim
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  #8  
Old 05-25-2023, 08:15 PM
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This doesn't make any sense. Is the return line run off a fuel filter or off a provision on the pump? If filter, maybe it's jinky.

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  #9  
Old 05-25-2023, 08:38 PM
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Return line comes out of the top of the fuel filter.

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Old 05-26-2023, 07:31 PM
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The fuel pump on the car, is not a vapor return pump as I had thought. But seems a pump with the return would be the answer of the stalling and doing away with the blue vapor return fuel filter.

Can anyone recommend a fuel pump allowing vapor return line, that will work in 65 326 engine. Am not putting much stock in these filters from far away.

JIm

  #11  
Old 05-26-2023, 09:25 PM
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Let me look at mine tomorrow.... It sounds like your set up may be corrrect. I'll be able to look in the morning.

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  #12  
Old 05-26-2023, 10:18 PM
wbnapier wbnapier is offline
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https://www.robbmcperformance.com/pr...ontiac550.html

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1965 Pontiac GTO
455/469 w/ #48 Heads, '65 Tri-Power
9.25:1 CR
Stump Puller Cam
Muncie M22W 1st-2.56 2nd-1.75 3rd-1.37 4th-1.00
3.55 Rear Differential
Front: 225/60R15 Height: 25.6"
Rear: 275/60R15 Height: 28"
  #13  
Old 05-27-2023, 09:09 AM
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Starting about 1966 or 67 Pontiac had pumps with the vapor return instead of the return off the filter. I suspect your "new" filter may be defective and have too large a hole into the return line. Take the filter off and see if you can get a look into the little 1/4 inch return nipple. If the hole at the top surface of the filter can is much more than what you could make with a needle it may be too large and is bleeding off the pump pressure when the return line is open. I just looked in a spare filter I have and I doubt the hole is 1/64 inch.

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Old 05-27-2023, 10:27 AM
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1st, sounds like a neat car. Here is a 67 pump with the vapor return, should work good. These pumps used 3/8" lines but if your fuel line is 5/16, it can be made to work.

https://secure.amesperf.com/qilan/De...A&web_access=Y

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  #15  
Old 05-27-2023, 11:00 AM
Singleton Singleton is offline
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If psi drops to 2 with the return connected, I'd say the filter was made wrong. It should not be sending that much fuel back to tank. Try a new filter

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  #16  
Old 05-28-2023, 06:17 PM
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Quote:
Originally Posted by pfilean View Post
Starting about 1966 or 67 Pontiac had pumps with the vapor return instead of the return off the filter. I suspect your "new" filter may be defective and have too large a hole into the return line. Take the filter off and see if you can get a look into the little 1/4 inch return nipple. If the hole at the top surface of the filter can is much more than what you could make with a needle it may be too large and is bleeding off the pump pressure when the return line is open. I just looked in a spare filter I have and I doubt the hole is 1/64 inch.
My Dec. 1966 Baltimore built '67 has original HD cooling and the vapor return is off the filter. No vapor lock issues or hot run issues at all. Works great. Click image for larger version

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