Jump to content
  • When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Preventing fuel from draining back into the tank


flagoworld

Recommended Posts

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.

'74 Verona

Link to comment
Share on other sites

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?

 

 

 

     DISCLAIMER 

I now disagree with some of the timing advice I have given in the past.  I misinterpreted the distributor curves in the Blue Book. 

I've switched from using ported-vacuum to manifold, with better results. 

I apologize for spreading misinformation.  

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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. :)

'74 Verona

Link to comment
Share on other sites

Okay, that makes two reasons to come for a visit.

     DISCLAIMER 

I now disagree with some of the timing advice I have given in the past.  I misinterpreted the distributor curves in the Blue Book. 

I've switched from using ported-vacuum to manifold, with better results. 

I apologize for spreading misinformation.  

Link to comment
Share on other sites

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. 

Link to comment
Share on other sites

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

 

 

     DISCLAIMER 

I now disagree with some of the timing advice I have given in the past.  I misinterpreted the distributor curves in the Blue Book. 

I've switched from using ported-vacuum to manifold, with better results. 

I apologize for spreading misinformation.  

Link to comment
Share on other sites

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

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • BMW Neue Klasse - a birth of a Sports Sedan

    BMW Neue Klasse - a birth of a Sports Sedan

    Unveiling of the Neue Klasse Unveiled in 1961, BMW 1500 sedan was a revolutionary concept at the outset of the '60s. No tail fins or chrome fountains. Instead, what you got was understated and elegant, in a modern sense, exciting to drive as nearly any sports car, and yet still comfortable for four.   The elegant little sedan was an instant sensation. In the 1500, BMW not only found the long-term solution to its dire business straits but, more importantly, created an entirely new
    History of the BMW 2002 and the 02 Series

    History of the BMW 2002 and the 02 Series

    In 1966, BMW was practically unknown in the US unless you were a touring motorcycle enthusiast or had seen an Isetta given away on a quiz show.  BMW’s sales in the US that year were just 1253 cars.  Then BMW 1600-2 came to America’s shores, tripling US sales to 4564 the following year, boosted by favorable articles in the Buff Books. Car and Driver called it “the best $2500 sedan anywhere.”  Road & Track’s road test was equally enthusiastic.  Then, BMW took a cue from American manufacturers,
    The BMW 2002 Production Run

    The BMW 2002 Production Run

    BMW 02 series are like the original Volkswagen Beetles in one way (besides both being German classic cars)—throughout their long production, they all essentially look alike—at least to the uninitiated:  small, boxy, rear-wheel drive, two-door sedan.  Aficionados know better.   Not only were there three other body styles—none, unfortunately, exported to the US—but there were some significant visual and mechanical changes over their eleven-year production run.   I’ve extracted t
  • Upcoming Events

  • Supporting Vendors

×
×
  • Create New...