bought this to fix fuel drain back problem

Fuel and Air Systems

  1. jos51700

    jos51700 Green Bearing thread connoisseur

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    An electric fuel pump solves all the above, especially if you install an EFI system with it ;-)
     
  2. memike

    memike Super Moderator Staff Member FABO Gold Member

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    Mo Money mo money jos51700, true but mo money
     
  3. trudysduster

    trudysduster Well-Known Member

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    well, here is an UPDATE on the fuel drain back problem.I brought this car home last week from the car show. it was hot. engine was hot. car has set for days now. I got in it today to get ready for a cruise in tonight and I pumped it twice and it fired right up. It didn't even idle irratic like it used to when it seemed like it was not primed. so, as far as I am concerned guys, it works for me. for about $9.00 shipped to my door I have considered this problem solved to this point. I don't know much how to include links on a computer but I bought it on ebay. the item # is:360517597852.The company is from the UK and their name is car parts international. They are really fast when it comes to shipping too. I am satisfied with it. I do want to thank you guys for all the ideas you mentioned but in this case, it wasn't evaporation. it must have been drainback.
     
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    • seabee

      seabee FABO Gold Member FABO Gold Member

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      Nice thread, thanks Trudysduster for sharing.
       
    • cudavert

      cudavert DARTAHOLIC

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      Carburetor float bowls themselves hold enough fuel to start and run the car for at least 5-10 seconds, which is definitely long enough to get the mechanical fuel pump pumping gas up and into the carb.

      If this check valve cures your problem, I'll be amazed.....I mean, I hope so but it makes absolutely no sense to me.
       
    • Gen2Cudas

      Gen2Cudas Well-Known Member

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      Subscribed.
       
    • trudysduster

      trudysduster Well-Known Member

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      understand what you are saying vert. but the difference is that it didn't do that before I put the valve in it. I had to pump the accelerator probably 20 or more times to get it to start. That tells me the fuel had to be draining back. that stopped. If the fuel was evaporating out of the carb, I would have to pump it in order to get it to run. I didn't have to do this this time. I will update again if the problem comes back. It may. I am not saying it wont. I don't know. I am just saying that it has been sitting for days now it it started right up. will let you guys know if anything changes.
       
    • sireland67

      sireland67 FABO Gold Member FABO Gold Member

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      Please keep us updated on how it works out.
      My dad's old truck will sit 3-4 months at a time, he is hitting 70 years old, so anything beats dumping gas in the carb to get it to start.
       
    • d55dave

      d55dave Well-Known Member

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      Think about it for a minute.....the fuel the float bowl in your carb cannot flow all on its own up, through the needle and seat, and drain back into the gas tank. It is physically impossible as the needle and seat is above the fuel level in the carb. It would be kind of like the water in your kitchen sink all on its own forming a water spout and going back into the faucet. The only plausible explanation - and every thermoquad that I have owned has done this (I haven't had many AFBs or their variants, but they may have the same issue) - is that the fuel evaporates, at least to a point where the accelerator pump is dry. An electric fuel pump causes this problem to go away as it runs before you try to start the engine, re filling the float bowl. When my carter equipped cars sat for an extended period of time I always cranked the starter first for a few seconds so the mechanical fuel pump re primed the float bowl, then stopped, pumped the gas pedal twice (accelerator pump) and they fire right up. Also realize that the accelerator pump pulls gas from the float bowl, not the gas tank, so pumping it 15 or 20 times to try to prime the engine is pointless unless the float bowl first has fuel in it.

      I would bet that you will find your problem is still there.

      Just my 2 cents
       
    • trudysduster

      trudysduster Well-Known Member

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      well Dave, I am having a hard time understanding how you can say that you bet my problem is still there when the problem is not still there. If everytime I start this car I have had to pump it numerous times for the past 10 years now I put this valve in it and now I only hit it twice and she fires, please explain this for me. wouldn't you think that if the problem was still there I would have to pump it numerous times. because if it was evaporating, putting the valve in it did not change the evaporating process. Sireland, I will let you know if it changes. Bill
       
    • RedFish

      RedFish Well-Known Member

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      When the fuel evaporates from the carb, it doesn't take a lot of cranking to get a fire.
      If the fuel runs back farther than the fuel pump, the car must be parked on a incline.
      That would require much more cranking to get a fire.
      I would like to know what is inside that check valve though. All brass construction ?
      Subscribed, good luck with it.
       
    • trudysduster

      trudysduster Well-Known Member

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      my car is always parked in a garage on flat surface. I have this valve inline just off the fuel inlet to the carb. I do not know what is inside the valve. It doesn't look like brass at all . It looks like aluminum or stainless steel.
       
    • RedFish

      RedFish Well-Known Member

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      I think any flow check should be vertical oriented unless there is a spring in it.
       
    • bruceo2011

      bruceo2011 Still waiting for Y2K

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      You installed it between the carb and the pump. Vertical or horizontal?
       
    • Bulldozer

      Bulldozer free ice cream sandwiches

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      that's great Bill, if its working , its working. I don't see why it would stop working unless the fuel pump completely fails
       
    • d55dave

      d55dave Well-Known Member

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      A couple of reasons your problem could appear to be gone - you could have bought fuel somewhere different than your normal station and its formulation is different making it less susceptible to evaporation, or your ambient air temp since you have put in the check valve has been cooler, again preventing evaporation. No sarcasm, just stating real physics. Fuel simply cannot physically drain from the carb float bowl back to the tank,the same as your kitchen sink cannot drain through the tap. Hope your problem is gone away, good luck.

      Dave
       
    • replicaracer43

      replicaracer43 Grumpy Old Man

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      x2
       
    • d55dave

      d55dave Well-Known Member

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      A little more information for you to ponder - your mechanical fuel pump contains 2 check valves already. It is essentially a diaphragm which moves and increases / decreases the volume of space between two check valves which open and close to pump fuel. Do you think that one more check valve, 1 or 2 feet away from the two already in the pump would have any effect?
       
    • memike

      memike Super Moderator Staff Member FABO Gold Member

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      My ramcharger does this (drains back ...) if I let it set for about 3 to 4 days... how why
      But it does........ could it be draining back because of my gas cap,fuel pump or is it draining in back because my float is not seating after the pressure is off of it when I shut the 318 off............ Hay mine does it and this is not new to us and our old carbs and pumps........ I will not run a electric fuel pump... More volts/amps being drew.. plus a manual pump is easy to change and find....... Glad to here it is working for you and I will be looking at getting me one It's not a racing HP engine.... DD and thank you for posting this up trudysduster, Keep us updated but I am sure this will rid you of this loosing prime problem, I know this has been a problem for many old systems like we run..
       
    • trudysduster

      trudysduster Well-Known Member

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      well, it is like I said before guys. I am not a mechanic. But I do have common sense. I know that when I have a problem for 10 years and I change something and the problem is not there immediately after the change is made, I call it fixed. Dave, you mentioned earlier about ambient temp. and buying fuel at different locations.well, I am going to bust your bubble again. I live in a small town. Every week when I leave for a car show, the first thing I do is fill my tank for the trip. and you guessed it. I fill it at the same watering hole. and as far as the ambient temp. goes, it has not changed more than 5 degrees this year between having the problem and after fixing the problem. Not to say you are wrong about these things, just that is not the case here. As far as the check valves are concerned, have you ever heard the saying, " third time is a charm". This may not work for anybody else. I am just saying it worked for me. I am like Memike. I will not run an electric pump. I almost burned a car up back in the 70's because of that and I do not like them. I will let you guys know if anything changes. But for $9.00 shipped, what have you got to lose.
       
    • kt340sport

      kt340sport Well-Known Member

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      Was just wondering , with this valve there would have to be some restriction of flow , and running a big block , with prob 650 or bigger carb , is there any issues on the street highway ect .Does it seem to be getting the fuel.
       
    • d55dave

      d55dave Well-Known Member

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      Yep, I get it. I am just curious and probably think too much, although my wife might tell you I dont think enough.... LOL. Enjoy the next car show!
       
    • trudysduster

      trudysduster Well-Known Member

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      well Kt340sport, I have not encountered any yet. Took it out Monday night to a cruise in and drove about 50 miles round trip and didn't notice any then. I am heading out Saturday to Indiana for a big car show at the Regatta on the river. that should be about 125 miles round trip. I will let you know after that if I have any problems.
       
    • trudysduster

      trudysduster Well-Known Member

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      Saturdays road trip went fine. drove it about 125 miles round trip. never had a problem with starting, running or with lack of power.so, I am going to assume the one way valve is working for this guy.
       
    • TylerW

      TylerW Well-Known Member

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      I think there are several people who are:

      A. Irritated they didn't try this idea first because the experts SAID it wouldn't work, or

      B. Irritated that they tried other things that didn't work and cost more than $9 or

      C. Not irritated but also not about to congratulate somebody else.

      Which is it?

      BTW, I also have fuel drainback problems on my stock '74 318, so I may be going your route, Good job!
       
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