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Preventing fuel from draining back into the tank

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Is there a consensus yet on preventing fuel from draining back down into the tank? Mine does this all the time and it's really annoying. I was thinking about installing an electric pump just to counter this, since it would be able to start pumping long before I start cranking. Thoughts? Opinions? Experience?  It would be cool to have all this info in one place.

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Did you try installing the frendle pin?

 

:D

  • Haha 1

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Yes but then i experienced side fumbling despite the lunar wane shaft.

  • Haha 2

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 I have a check valve, brand new PM me and I will send it to you for free.  Just pay shipping, Can Post.

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Where is the check valve supposed to go? Is it part of the stock system?

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Check valves FTW! I have one installed just after my fuel pump in the trunk, and another either before my regulator... or before the carbs... I forget. It happens.

Allot.


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I've got a check valve you can have.  I bought a five pack online a while back. 

 

I removed the one I installed and use it on the end of my siphon hose.

 

What kind of fuel pump do you have Ryan?

 

 

 

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5 hours ago, Dudeland said:

I have a check valve, brand new PM me and I will send it to you for free.  Just pay shipping, Can Post.

I requested a check valve from you....about a year ago! 

Please let me know what the Can Post charge is, and I will gladly sent it to you.

John

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1 hour ago, '76mintgrün'02 said:

I've got a check valve you can have.  I bought a five pack online a while back. 

 

I removed the one I installed and use it on the end of my siphon hose.

 

What kind of fuel pump do you have Ryan?

 

 

 

 

I have the stock mechanical pump. I'll take one of your check valves then. :)

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I requested a check valve from you....about a year ago! 
Please let me know what the Can Post charge is, and I will gladly sent it to you.
John

So sorry. Pm will come tomorrow


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I installed a check valve near the gas tank - one that I got on Amazon that is probably the same as those described by others.  The car has the stock mechanical fuel pump and a new fuel line.  As far as reducing the cranking to start after a couple of weeks sitting, it worked great.  However, my car developed a severe intermittent fuel starvation problem.  Sometimes just an occasional miss, other times it would just stop running.  I had to get pushed off the road one time when this happened.  ( A driver of a new BMW came to my rescue.)  I pulled the check valve out and took it apart to see if that was the culprit and it appeared to be working fine - it's a pretty simple device.  I tried not reinstalling the check valve and the problem totally disappeared and has never returned over the past six months.  

 

I wonder if anyone else has experienced anything like this or did I just get a weird bad check valve. 

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I removed my valve (installed by the tank) in a trouble shooting spree.

 

Took it apart too, just to see what was inside and found a weak spring and a thin rubber disc.

When I blew through it, I could make the rubber flutter, like a little kazoo.

 

Around that same time, I removed the new stubby-style fuel pump and reinstalled the old sealed-top taller one that came on the car.  It works as it should, as in, it acts like a thumb on a straw, keeping the fuel in the line.

 

I am wondering about your fuel tank vent. 

 

Mine runs into the air cleaner, but was plugged with a screw by the previous owner.  I learned this when I put the fuel return line back into service (plugged with a bolt by the previous owner), during the jeep fuel filter installation. 

 

After installing the filter and before removing the little vent screw, I was pressurizing my fuel tank with the returning fuel.  Sort of a tangent, but it is all part of the system.

 

If the vent line is plugged and you are removing fuel, you are creating a vacuum in the tank, which could conceivably suck it back out of the pump.

 

If the vent line is open/not plugged up, I'd be questioning the valve inside the fuel pump.

I don't recall having seen the cutaway of any of our pumps, but this must be similar ... in some way ( too bad ours don't have that return line fitting).

image.png.1d2cfeedcc15a142a7f6067b13657dc2.png

 

 

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1 minute ago, '76mintgrün'02 said:

 

If the vent line is open/not plugged up, I'd be questioning the valve inside the fuel pump

 

+1

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Vent line not plugged.  No fuel return line on my 71.  Fuel pump appears to be original, but can't say that for certain.  The pump seems to operate quite normally.  I would think that if any of those possibilities were the cause of fuel starvation, it would continue with or without the check valve in place.  

 

Since no symptoms have appeared since removing the check valve, it sure points to that being the culprit.  But as you found when you took yours apart, it's such a simple device that it doesn't seem very likely to plug up.  It's a head-scratcher to me.   Perhaps your thought about the fuel pump inlet valve somehow malfunctioning might be part of the problem - and maybe it is somehow related to the check valve putting more suction stress on it than normal. 

 

I thought about trying a different check valve - there's a somewhat more expensive one on Amazon that is sold as being meant for diesel engines that I thought about trying, but the diesel part threw me off. 

https://www.amazon.com/dp/B078PBMY49/?coliid=I229I8EX1YZMKQ&colid=3UL0M0O64CNNJ&psc=0&ref_=lv_ov_lig_dp_it

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