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project "idle hands"

9K views 57 replies 8 participants last post by  brinner 
#1 ·
so it's time to unvail the next project. This project is actually version 3.0 of an on-going issue.

What is it? a new fuel cell/gas tank. Having plenty of time to think everything out about my truck not running, re-evaluating all the symptoms etc. I began thinking that the motor and sensors have all checked out, but the truck was acting as it not getting fuel. Thus realizing that it was creating a vapor lock situation in the fuel system.

So with everything in the bed already configured in a way not condusive with moving the current fuel cell up into the bed, I have built (in progress of building) a new gas tank.

The aftermarket tank I currently have can not be retro-fitted into the bed nor can I relocate it under the truck in order to make the changes needed to eliminate the current issues.

Those issues being #1-the tank being located so far back on the truck or away from the fuel rail #2- the aftermarket rail mounted fuel pump is not lower than the bottom of the fuel cell nor will I be able to properly mount it in such a way.

The gas tank needs to be closer to the engine compartment, mounted high enough on the chassis that will allow gravity to feed the fuel pump yet out of the way of exisiting fixtures and systems already in place.

This is solution I have devised;
I have already test fitted this mock tank in location and it fits nicely and is very inconspicous behind the tire carrier. In this location many people have made fuel cells work with other trucks so the position should work nicely in feeding the fuel system.

The plan is to actually place a line boss directly in the center of the floor and have the fuel line ran from under the tank, thus providing plenty of gravity feed to the fuel pump and then onto the fuel rail. Currently the fuel pump is not below the fuel tank and if you have every tried to syphon a fish tank you know you have to keep the recieving bucket below the aquireum level for proper water flow...this is not what I currently have on the truck.

I have already begun the tank construction, using 16 gauge metal. Once I have the welding complete and visually inspected, I will fill with water to find any pin holes or other potiential flaws. Afterwards I will seal with gas tank sealant and test a second time.

here are some additional mock up & progress photos.




the flat piece of metal at the angled side was a temporary brace used to keep
things square until the body was tack welded in place, since been removed





Estimated volume of the tank is right at 17 gallons which I'll be loosing 4 gallons from the plastic tank I have but won't loose much from the factory tank. I'll also gain back all departure angle lost with the other tank as well as plenty of room for the 4 link I still plan to install for my rear suspension if I ever regain the finances to finish.

I'll have updated photos as progress is made.
 
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#32 ·
That's cool. I'm taking a break from the garage tonight. After almost 10 years of being married I've almost figured out some of Momma bear's hints.

The only thing I can guess @ what you might be thinking about is kind of like a closed "loop" type of tubing. Like a french drain type of thing, but that would still introduce air. So Ikm anxious to see what ideas you have.
 
#33 ·
What kind of pressure does the system "pull" at the pickup tube?
 
#34 ·
I wouldn't have a clue. I would expect it to be minimal. With the external electric fuel pump being a "pusher" not "puller" I would guess under 25-30 psi.

After the pump, we should be getting over 160 liters per hour. Think that would be around 70 psi. But like Jason pointed out, I need to put a pressure gauge in the system
 
#35 ·
Well I can't get MS paint to cooperate. Setup I'm thinking of involved one larger tube, horizontal or slightly off kilter, connected to two pickup tubes. One crosses over to the opposite side where it exits the larger tube, and vice versa for the other side. Put the ball bearing in the larger tube, make sure the ball bearing is larger than the actual main pickup tube. Kinda see what I'm getting at?
 
#36 ·
I got the photo, still looking it over to understand everythying. In the mean time I sent you a photo of what I foresaw as well. Looking for your thoughts on this.

:xofftopic its interesting trying to draw/design while on narcotics. I may have o continue in the am.
 
#37 ·
no actual progress to report, because frikken check valves are expensive!

I think I am going to take Grants suggestions and expound on them. I would prefer to have a duel pick up type of set up over putting baffles in the tank, although baffles would be cheaper and thus quicker for me to finish. But weighing the pros and cons of the two, in addition to always attempting to do things the right way the first time, I am holding out until I can afford the needed "ingredients.

Here is some of the thinking; although the baffles would be easy to cut out, and then cap over to seal the tank, it still limits the tank to having a single pick up in the center. since the truck will be off camber more than level I believe it will allow the truck to run lean more than not.

Having duel pick ups creates a unique problem also caused by the truck being off camber in that when one of the pick up ports is dry, air will be allowed into the system causing a similar vapor lock to what I suspect is the current problem.

As Grant suggested running a pick up line from either end parrallel to the floor with a ball bearing as a check valve would be a good solution. I am investigating the availability of simple check valves at each port. this should simplify the design that will eliminate extra parts that could fail as well as add weight.

I have found some check valves from Summit and Jegs for $40+ but I am wanting to talk over this idea with a local speed shop so that I can put my hands on the parts before blindly spending the money.

But even with the delay, I am hoping to have my truck rolling within the next couple of months. It's a strange feeling to actually have some optimism again over this problem plaguing me for the better part of three years.:mad:
 
#38 ·
Hopefully this cures the issues you have been plagued with.

I dont think simple check valves are gunna solve your conundrum. I think you will need some sort of float valve that is spring loaded, so it will open when submerged, but close when not submerged via the spring since gravity wont always be working in the proper direction for you, lol
 
#39 ·
A float valve was one of my intial thoughts also. But then you have to think about tention & how effective it would be in sealing the port etc.

Summit has one particular check valve that is a "clapper" type valve AND is spring loaded. Opens under .05 psi but closes w/ gravity if I remeber right. I want to see if my local speed shop carries anything similar. If so I'll be good to go if it doesn't work then I'll go another route or recruit Grant to build the pick ups for me ;)
 
#40 ·
All check valves open under a differential in pressure in a specific direction. If you use any check valve it must be installed to open when suction is obtained from the pump side (the only way to get flow from the tank to the pump).

The negative pressure developed by the pump will actually most likely do the opposite of what want and open to the air side when off camber, because it will take less dp (differential pressure) to open the air side due to the additional suction required to flow the fuel through the other one, air flows easier than any liquid.

Please don't take this the wrong way, I am all for new ideas. I actually like the way Grant is thinking, and if his idea were commercially available I would say go for it as well, but I fear the prototype may end-up costing more and being more trouble than something you know will work right off the bat, that was engineered to do exactly what you need.

Not my :2cents: we're talking about so I just hope you find something that works. I wanna see that thing in action at Fall Crawl. :D
 
#41 ·
I'm hoping it will be running long before fall crawl but that is another thread.:banghead:

Your reasoning regarding differential pressure and negative pressure etc. is why I want to personally discuss my ideas with my local speed shop/vendor. This guy outfits all the local race teams from midgets, pavement oval/nascar to top fuel and funny car teams & hot rod shops so if there is something commercially available he should have knowledge of it. He's been in business for over 15-20 years, you know the name of the shop even if you have never been to Indy...It's Earls. the same company that manufactures all types of automotive plumbing fittings.

I actually thinks he likes working with me on this as he is first to admit that he is "learning" off road needs as I come in to talk to him about it.. But you have to admire that kind of enthusiasm if for nothing else.

I am not dismissing Grant's idea, but as I tried to explain to him and as I am sure you have recognized in me in the past, I am "visual thinker" it is much easier for me to understand if I see ideas in pictures. So I am having a bit of a harder time understanding how Grant is wanting to set up the valve system. (I was also going to describe Grant's idea to my vendor so that he can either source those parts or explain it further to me)

What I am not understanding about Grant's suggestions is how do you keep the bearing "valve" in the proper location? I mean how does it not plug up the port when on level terrain? AS I understand Grant's concept is the pick up tubes are bent so that they are horizontal or parallel to the floor of the tank. The 90* is "uphill" to the port it is acting as a valve for (bent to the left for the driver's side and bent to the right for the passenger side/bent toward the end walls) so that gravity will pull the up hill side, ball bearing over the hole when the truck is driven off camber but how does the bearing move out of the way when the truck levels off? Also when in a neutral position how does the ball bearing stay out of the way and not plug up the hole? or is it randomly rattling around? IF it is randomly moving what happens if both valves plug at the same time? it plugs the fuel flow causing the same current issue I am having. IF you cut a slot in the tube to circumvent that issue then you are back to square one by allowing the system to pull air opposed to fuel.

These are the issues I am still trying to figure out with Grant's suggested way of building the pick up tubes. IF you or him could answer those questions, I would feel more confident in building the ball bearing, duel pick up. (which will be forever known as "Grant's gravity duel feed system")

I think you know me better than to think I am would take offense over any one suggestions or offering constructive criticism so any help is appreciated especially since I don't have any formal training in engineering. I learn as I go... you know that!;) but I like to think I have had more good ideas than bad, and I like surrounding myself with knowledgeable friends IE TTORA mates!:cool:
 
#42 ·
I will attempt to further explain Grants idea when I get a chance. For now my only issue with his idea is that conceptually it should work, however the design would need some refining and engineering. In order for the ball bearing to properly seat and seal you are talking about some considerable custom machining to incorporate rubber seats/seals into the fitting his design would require.

I also see your point about the bearing blocking the main port when level, but I think that could be designed around as well.

If I get a chance later on this afternoon I may sketch something up, but works kinda busy today.
 
#43 ·
...
...works kinda busy today.
you bragging or complaining?;)

If this becomes too complex, I'll just cut the baffles into the tank and call it a day. but I appreciate all the help. This is the true concept that I wanted to build the chapter on.
 
#44 ·
Yeah the concept is simple, but finding some one that makes something like this for your application is hard.

I just keep envisioning something like a small engine carburator bowl on each end of the tank for a pickup, only with a slight spring force (instead of gravity) to hold the float down. When fuel is in that pickup, the float can overcome the springforce and allow fuel to flow.

Got any carbs laying around?
 
#51 ·
...
I just keep envisioning something like a small engine carburator bowl on each end of the tank for a pickup, only with a slight spring force (instead of gravity) to hold the float down. When fuel is in that pickup, the float can overcome the springforce and allow fuel to flow.

Got any carbs laying around?
I know I am slow, but I think I finally realized what you are talking about with the above description. You are thinking of a baffle box correct?

I can't draw it here but what I am envisioning regarding a baffle box is a five sided cube (including the floor surface) with the two end pieces being one way doors closing inward and sealing outward. These doors would be on springs so that when the gasoline is sloshing back and forth inside the tank the doors will be flapping open trapping gas inside the box/cube.

The is very similar to how the stock tanks are built which is a very solid idea. the box does not need to seal tightly and should contain approximately one pint of fuel which would be enough to maintain momentum over immediate obstacles/off camber situations.

I have all the materials already to be able to build a baffle box so that is also a strong option. I still like the displacement ball idea as well so plans are to research them a bit further but have a decision by today in regards to which way to proceed.

I appreciate everyone helping me get to this point. So thanks everyone.
 
#45 ·
here is the check valve I found which I want to research a bit further.


http://www.jegs.com/i/JEGS+Performance+Products/555/150021/10002/-1

I remembered the opening pressure as .5 psi, but I was wrong, it is 5 psi. But with the placement of the fuel pump and the capacity of the tank I don't think 5 psi will be an issue.

this check valve is advertised as having a torsion spring to close the valve. This still seems the simplist solution to me, but I am still open to discussion. (obviously)
 
#49 ·
I am also deliberating on the effects of fuel cell foam to at least slow the sloshing it, it maybe the solution if I end up with a single pick up port with the baffles.

I rarely get out of the house these days due to the cost of diesel but I think I will make a trek over to gasoline alley to discuss all these options with the owner of Earls tomorrow
 
#50 ·
Since Grant suggested the ball bearing valve I have seriously figured this was the way to go. After about an hour of researching the progressed ideas from his suggestion, Mark's opinions and my further brain storming, I have come up with somewhat of viable plan incorporating a little from everyone.

I found a specific racing valve offered through some very high end racing vendors (F1 type equipment) called a discreminator valve it actually closes when air is introduced in place of fuel/liquid. Problem is they are very expensive.

But in researching that particular valve, I ran across another product that some sanctioning racing bodies require. they are called volume displacement balls.

They are come in various sizes with the smallest being about the size of a ping pong ball. impervious to gasoline and they float.

So the idea of Grants ball bearing is alive and kicking! what my proposed idea is to purchase two of these balls, (may have to import from england) I have some scrap 1 5/8 tubing in which I can create a cage for the balls to float in while the particular port is wet.

When the port is dry the ball will fall over the port and sit in a bed of rubber sheeting that will be secured to the edge of port. the secure seal Mark is concerned about will be achieved by the rubber bed and O ring.

I just have to source the displacement balls as I have all the rest of the materials on hand. Should be meet all my requirements, simple, cheap, and works with the natural laws of gravity.
 
#52 ·
Well crap!!!!!!!!

As it is 1:20 AM on Thursday I have yet to make a decision regarding the tank pick up system. But it is definitely not due to lack of thought or effort on the topic. I did spend most of the day actually focused on gaining employment, the afternoon and night were concentrated on deciding the best route of picking up fuel in the tank and I thought I was making progress.

At this point I have concluded that creating a custom pick up will NOT be problematic, I just have to figure out how I want to do it out of roughly three options.Yup! I just made the previous statement, the pick up system is highly viable.

Option #1- drill 3/8" holes in both ends of the floor to install -6an bulk heads into the tank. Above the bulk head, construct a cage that will house a single 1/2" hollow aluminum ball that will act as a float. When that individual port becomes "dry" in off camber situations, the aluminum ball falls directly over the port and seals against a fixed "O" ring. When gasoline returns to the end of the tank, the ball will rise in it's restrictive cage returning flow to the port. The rubber "O" ring will provide a positive seal sufficient enough to close off air flow by combination of gravity and negative pressure created by the draw from the fuel pump and flow of the alternate port.

Option #2- build a baffle box to encompass a single port in the center with tension sprung trap doors... This box can hold as little as one pint of gas and still be effective. Addition baffle "walls" would be recommended as well to reduce sloshing and weight transfer. since the tank will be holding a rather high & heavy payload.

Option #3- Which is a new option stumbled upon late in the evening. Obviously this is not a new or unique problem and it has been solved in the past by borrowing technoledgy from the drifting community using in tank pickups made by Walbro for the Holly corporation. The drifting community borrowed this technique from Snow mobilers that run EFI on their sleds

Basically you place (multiple) 70 micron mesh baskets inline on either end of the tank pictured here:





The pick ups are attached in line with each other on the bottom. There are four styles, the end filter,

90 degree,

and the pass through


the product description explains the concept much faster and clearer than I ever could so I will also cut and paste the entry from A.P.E (Automotive Performance Experts) here:

"How they work:
Have you ever sprayed water on a window screen? Recall that the screen will actually hold some of the water. These pickups work the same way. When the pickup is submerged in fuel, the fuel will pass through the mesh with ease. When fuel sloshes away from the pickup, the mesh will hold enough fuel to fill all the tiny holes. That mesh full of fuel acts like a solid. At this point, the pump, sucking on the pickup will cause the mesh to suck shut, preventing the pump from sucking air. When fuel covers the pickup once again, the valve will open up and transfer fuel."​

They further claim that "These pickups have been tested in gasoline to -40 F and in diesel fuel to 0 F. A single pickup can flow 40 gal per hour, so they work well with high-performance applications, too."​

So again, I have to think about which technique will be the overall "best" for my application.​

If I make my decision solely on expense, I would have to say the trapped aluminum ball idea will be my cheapest since I can order a pack of 10 for $9 + shipping and buy some additional -6an fittings​

But the Walbro pick ups require less modifying of the tank from the state it sits now, the other obsticle it may present is anchoring the baskets in the location I want. But if you find stiff enough tubing and the proper adhesive you could secure a magnet to the bottom side of the basket and hold them to the floor of the tank. In addition to deciding, it appears that I can only source the Walbro baskets via two sites with little difference in price, thus my continued :google: parade. Tomorrow I plan to search out Snow mobile vendors.​

So it seems the problem is solved for the time being...just in which way I am not sure of yet!:xcrazy::aahg:I am glad I don't have to rely on BearAttack to get me to work and back. I would have been fired three years ago;)
 
#53 ·
.'Marrow we'll begin making progress again on this nightmare. We/I need to finish putting a new top on a miata so I can get my work space back.

Once I do that, Momma Bear promised to spend some time with me in the garage like old times. So the motovation should be flowing & I'll have a set of extra small hands helping get to all the potential small areas. We are actually needed to clean the cell out one final time and then spread sealer on the interior. The P.O.R 15 gas tank sealnt takes 96 hours to cure so that should give enough time to order thwalbro multiport pick ups...

In speaking with A.P.E (auto perfromance engineering) the size of my tank is perfect for two. They also mentioned the way to secure them pick-ups was best done using stiff tubing and just let their own weight keep them on the floor.when I told them all my fuel lines were made out of brake line the guy got all excited & said I was a step ahead of him. So I guess that's the right material to use. What I did not tell him was I plan to secure the lines to the floor with hooks anchored by magnets.

The magnets will also act as filters for some of the trash found in local stations holding tanks

Using the brake line will also make it easier to connect all the tubing. Rubber fuel from the actualpick ups to 3/8" line to a bulkhead tee with it's third leg going to the outside & straight to the fuel pump
 
#54 ·
Okay, over the Easter weekend, we finished replacing the convertible top on Cub #2's Miata. talk about a P.I.T.A job but it was a pretty good learning experience for Cubby & to tell you the truth, I ended up supervising more than turning a wrench.

I also reviewed some of the seams on the tank and hit the questionable ones a second time with the "glue gun". I also decided on the pick up system I am going to use.

I decided on using the the Walbro Mp-12 idea. After reviewing all the info over on Pirate, as well as talking to A.P.E performance out of Dallas who sells them, it seems to be working good on rock crawlers. I specifically asked A.P.E about vapor locking and whether it was a sales pitch or not, they said that these pick ups have solved this problem in the past on some street racers.

I also cleaned the inside of the tank tonight in preparation of sealing it tomorrow. I ended up pressure testing the tank with water in the process in addition to "impact testing" "under load" :eek::mad:. I am not the happiest with the capacity of the tank, I am ending up with 16 gallons. I was hoping for a minimum of 18 gallons. I am also not happy with the dented corner from the drop, but overall it passed the drop test.

I also still have a few pin holes which should be sealed by the sealer, but I am going to touch them again with the welder before sealing, better to be safe with this particular part.

Since the sealant cures best with 96 hours lead time (4 days) I am thinking I should be able to start installing the tank by mid week of next week. Which gives me time to take my time building the pick up system.

The complete plans for the pick up is to place two of the Walbro pick up baskets (one at each end), connect them to a tee fitting by either 5/16" or 3/8" brake line. I'm also going to fasten the lines to the floor of the tank with magnets although I should not need to using hard line. The magnets should also act as a trash collector away from the baskets.

Fasten the Tee fitting threw the floor of the tank and then straight to the fuel pump that I am hoping I will be moving to the right below the bed ino the back wall of the bed under the floor of the bed. From the fuel pump to the fuel rail will use a small section of hard brake line to the factory fuel line into the fuel rail. This plan moves the fuel pump under the fuel tank as well as shortens the distance substantially between the fuel cell and pump in addition to having the pump fed strictly by gravity

(Brinner: FWIW, I reread the can of P-O-R 15 sealant I am using, and the can says it is safe to use with ALL fuels and additives)
 
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