Gain extra benefits by becoming a Supporting Member Click here find out how!
Silver
Gold ***Platinum***
50chev1067 (2)Don H (5)Runningon6zonk2ajoda (6)
ShoeboxTOMD45 buscobill
1963SBHD (4)Dean50 (8)Backyardbuild jumbojim (3)
InkaholicMike (3)
Classic Performance Products
Ciadella Interiors American Auto Wire Art Morrison.com
Exile® Battery Keeper™ 6/12 volt charger w/ LED battery monitor
Hellwig Products IncPerformance Rod & Custom
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy

  >> Switch to Mobile Version <<

Recent Hot Topics
Current Quote
"I am amazed by how knowledgeable and helpful folks on this forum are, and I am grateful for any help you may send my way."
~ Supporting Member
Recent Topics
Join the Community today
**
New ** Easy eBay Search Tool







Username Post: Dual Fuel Tanks        (Topic#236034)
Abowsman 
Forum Newbie
Posts: 40

Age: 31
Loc: Atlanta
Reg: 02-18-10
02-19-10 07:08 PM - Post#1865876    

So I have a truck that I have been working on getting the dual fuel tanks working again. The previous owner rigged it up something scary. Had a rubber fuel line laying on the exhaust and about half an inch from the driveshaft.
Its a 1983 with a newer model 350, so I am gonna need an electric fuel pump. I was just wondering if i can put the fuel pump on the frame rail after the selector valve. I know the selector valve controls the tank level indicators but does it also change which tank the fuel is drawn from??? Also wondering if the fuel pump will have enough suction to pull the fuel out of the tank or if i need to put fuel pumps in each tank?


 
Vaughn 
"12th Year" Gold Supporting Member
Posts: 15232

Loc: Colorado Springs, CO
Reg: 08-08-04
02-19-10 10:10 PM - Post#1865969    
    In response to Abowsman

You CAN, but it isn't the best of all possible worlds. If you are going to put a fuel pump on the frame rail, do it just after the selector valve, and make sure it is a vane style pump.

Vane pumps can self prime, which is why they are better than solenoid pumps - in this particular application, where you may have a problem with priming. They also flow more fuel and provide more pressure than solenoid pumps.

You would want to use a TBI pump, because they put out 14 psi versus a TPI/Multiport fuel injection pump, which would put out 45 psi. Some of the early fuel injected (82-85) Cadillacs had a TBI pump that mounted to the frame rail, if you have trouble finding one search using the 82-85 cadillac info.

The only drawback to using a vane style pump is that you will have to use some kind of pressure regulator to reduce the carb inlet pressure to between 4-7 psi. It's best to use a return style regulator (and you already have the lines for it plumbed from the factory), but if your really need to watch your money you can get by with a dead head regulator (it will be about $40 cheaper).

Yes, the best way to do it is to have dual in-tank pumps and a tbi (pressure rated) selector valves like in 86-87 pickups with tbi - but this a bit more hassle to do. If you have the donor vehicle to strip it all from it would be great, but if you don't it would nickle and dime you to death buying it piecemeal.

 
troyd1 
Forum Newbie
Posts: 78

Reg: 03-22-09
02-20-10 05:07 PM - Post#1866274    
    In response to Vaughn

I am not questioning your knowledge but would like to see someone else agree with you.

I have been thinking about this subject as I too would like to install dual tanks on my 81 that is converted to tbi (holley projection)

I decided it would be best to install two tanks with one filler tue feeding both. This allows mw to fill both tanks from one fill location eliminating the need to cut a fill a hole for the filler on the left hand tank.

I would install a high volume low pressure pump to pump fuel from the left tank to the right one to keep it full.

In my head it is easier to do this way with less things to screw up. I planned on having two fuel guages and a manual switch to operate the pump so I could monitor fuel levels as I am pumping fuel from one side to the other.

If you could really install the pump after the selector valve I would do it this way as it is much simpler and eliminates the need for 2 pumps.

I just have never seen it done that way so I assumed it was a no go.

2 votes for selector after pump and I'm in,

 
Anonymous 

02-20-10 07:08 PM - Post#1866348    
    In response to troyd1

  • troyd1 Said:
I am not questioning your knowledge but would like to see someone else agree with you.

I have been thinking about this subject as I too would like to install dual tanks on my 81 that is converted to tbi (holley projection)

I decided it would be best to install two tanks with one filler tue feeding both. This allows mw to fill both tanks from one fill location eliminating the need to cut a fill a hole for the filler on the left hand tank.

I would install a high volume low pressure pump to pump fuel from the left tank to the right one to keep it full.

In my head it is easier to do this way with less things to screw up. I planned on having two fuel guages and a manual switch to operate the pump so I could monitor fuel levels as I am pumping fuel from one side to the other.

If you could really install the pump after the selector valve I would do it this way as it is much simpler and eliminates the need for 2 pumps.

I just have never seen it done that way so I assumed it was a no go.

2 votes for selector after pump and I'm in,



You're talking apples and oranges...

On pre-fuel injection trucks, the fuel pump was located on the engine.

On fuel injection trucks, the pumps were located in the tanks.

Pre-fuel injection trucks use a different tank selector valve than fuel injection trucks.

My take is this...the pre-fuel injection truck selector valves were designed to have fuel "pulled/sucked" through them...not "pushed" under pressure.

I just replaced both of my fuel tanks, and the selector valve, then I installed a filter, then the pump. My 85 Pickup has a 350 Vortec engine vs the original 305.

The only difference in the fuel system is that I added an electric pump AFTER the selector valve and the filter...vs a mechanical pump in the same configuration.

 
Vaughn 
"12th Year" Gold Supporting Member
Posts: 15232

Loc: Colorado Springs, CO
Reg: 08-08-04
02-20-10 08:51 PM - Post#1866415    
    In response to Bobs85PU

That is what we were talking about - placing a vane pump between the switching valve and the motor. It would be set up so that it sucked fuel through the carb style switching valve.

Feeding both tanks from one stock-location gas cap can be done, but you will have trouble getting the gas to flow to the opposite side tank, because there isn't enough of a drop to that side to allow gas to flow to the passenger side tank. You need at least a 1/4 inch drop per foot, which will lower the tank on the passenger side about 2 inches, or you can move the filler neck down on the tank - but that will cause you to lose 2 inches of fill on the top of that passenger side tank. If you try running a tube over to that tank at nearly level, it will constantly be shutting the fuel filler off because of fuel backing up in the pipe.

You could do what racers do - they run both fill tubes to one side of the vehicle. It involves mounting both fill tubes high on the body - probably high into the side of the pickup bed, to allow enough of a drop so that fuel flows readily to each tank. But if you haul anything in the back of your truck - you could crush the tube running from the drivers side to the passenger side tank.

You can set up a pump to move gas from one side to the other, but if you do that you might as well install a pump in each tank.

The style of tank that you are referring to is a transfer flow tank, and it usually involves more complexity than you think. If it doesn't have a separate fill, your pump needs to be reversible so that you can pump fuel one way or the other - if not a reversible pump, you will need two one-way pumps (or pumps with one way valves) to be able to move fuel from the driver's side tank to the passenger's side, and from the passenger's side to the driver's side. Including the pump to the motor, that would make three pumps - with separate wiring for each. In addition, there would be a significant lag in pumping from one tank to the other - so you wouldn't be able to pump enough fuel over to the other tank while filling up the drivers side tank - it would take 10-15 minutes to move fuel from your drivers side to the passengers side. So, your time in the filling station waiting for it to pump over might be longer than you think.

So now you know why GM thought it was easier/cheaper to have fills on the opposite sides of the truck, even though it created extra hassle for the owner.

 
RunAndGun 
Contributor
Posts: 410
RunAndGun
Age: 47
Loc: Mckinney Texas
Reg: 05-16-09
02-21-10 09:42 AM - Post#1866627    
    In response to Vaughn

Back in the stone age when I worked at a dinosaur body repair shop:

Sometimes a single tank bed was used as a replacement on a dual tank truck.

It was pretty straight forward and effective to mount the stock filler tube to the front and outside edge of the wheel well. One could access it at the pump just fine.

This would be the simplest way IMHO.

I am a little dense I know, but I missing why you are mounting a high pressure fuel pump to a carbed engine?

..........Sean
1984 4WD Short Step Side
305 4Bl Quadrajet, 700R4


 
Anonymous 

02-21-10 11:55 AM - Post#1866687    
    In response to RunAndGun

Not a high pressure pump...just an aftermarket electric fuel pump.

My fuel pump feeds an Edelbrock 1406 (600CFM) carburetor.

 
troyd1 
Forum Newbie
Posts: 78

Reg: 03-22-09
02-21-10 08:27 PM - Post#1866953    
    In response to Vaughn

Now you've ruined my whole plan. My friend suggested that I run a pipe over from the original filler hole to the second tank.

I went under it and looked things over and thought it looked do able.

I had a perfect pump in stock that would do the transfer.

I am interested in this modification as I am from Canada live very close to the USA and would like to take advantage of your lower fuel prices.

I just filled up tonight and gas is about 1.60 per gallon cheaper than here in Canada.

You are allowed to fill your vehicle only (no containers) and they are on the look out for homemade containers and things like extra tanks in the box.

I debated cutting my own filler hole but didn't really want to do it.

This cross over idea was the ticket. Now I'm back to square one. I have been thinking about this for a while and am trying to keep the costs down as the payback in savings in gas takes a while to recover the money you put out in parts.



 
Anonymous 

02-21-10 09:23 PM - Post#1866998    
    In response to Bobs85PU

  • Bobs85PU Said:
Not a high pressure pump...just an aftermarket electric fuel pump.

My fuel pump feeds an Edelbrock 1406 (600CFM) carburetor.



Sorry guys, now it was me talking apples vs oranges...I didn't realize you were discussing a transfer pump!!!

 
RunAndGun 
Contributor
Posts: 410
RunAndGun
Age: 47
Loc: Mckinney Texas
Reg: 05-16-09
02-22-10 07:57 PM - Post#1867640    
    In response to troyd1

  • troyd1 Said:
Now you've ruined my whole plan. My friend suggested that I run a pipe over from the original filler hole to the second tank.

I went under it and looked things over and thought it looked do able.

I had a perfect pump in stock that would do the transfer.

I am interested in this modification as I am from Canada live very close to the USA and would like to take advantage of your lower fuel prices.

I just filled up tonight and gas is about 1.60 per gallon cheaper than here in Canada.

You are allowed to fill your vehicle only (no containers) and they are on the look out for homemade containers and things like extra tanks in the box.

I debated cutting my own filler hole but didn't really want to do it.

This cross over idea was the ticket. Now I'm back to square one. I have been thinking about this for a while and am trying to keep the costs down as the payback in savings in gas takes a while to recover the money you put out in parts.





Why didn't you just say so!!

I am all about a little harmless smuggling. I have been know to wrap an extra bottle of booze in a blanket coming out of Mexico or stick an extra pack of cigarettes in my boot.

Install a stock fuel tank on the other side. You don't even have to hook up the selector switches, lines or solenoids if the authorities are not looking for it.

Route the gas filler tube in to the wheel well. The standard stock hose is long enough. Fill your tanks and transfer it at your leisure in to your working tank at home.

.....Sean
1984 4WD Short Step Side
305 4Bl Quadrajet, 700R4


 
Abowsman 
Forum Newbie
Posts: 40

Age: 31
Loc: Atlanta
Reg: 02-18-10
02-24-10 08:45 AM - Post#1868613    
    In response to Vaughn

Thanks for all the interest. I am new to this site and its nice to know there are others out there willing to take their time to help me out.
And especially thanks Vaughn for your input. When i originally got the truck it had a solenoid type pump installed and from what i could tell they had it hooked up to both tank feed lines. Not sure why but this is how they had it. Well when i took all that out and hooked up the selector valve again and put the SOLENOID pump inline just after the selector valve i had no fuel comming out of the pump. Well i had one of those cheap little VAIN type fuel pumps from auto-zone and it pumped the fuel great. So your are exactly right about the different style of pumps. Very important to anyone else out there reading this.
Well i guess i just had some dumb luck because the vain fuel pump i put in wuit working later that day. Probably just an old pump. I ordered a new Holley electric fuel pump, regulator and press gauge. Hopefully that cures the problem.
Any suggestions on fuel pressure for it. The motor is a stock 350 mid to early 90's with a quadrajet carb on it. I was thinking about 7 or 8psi.


 
Vaughn 
"12th Year" Gold Supporting Member
Posts: 15232

Loc: Colorado Springs, CO
Reg: 08-08-04
02-24-10 03:41 PM - Post#1868838    
    In response to Abowsman

4 to 7 psi is a common stock carb inlet pressure. IF you had a performance carb with a better needle and seat, you might be able to get away with up to 9 psi, but you should really regulate pressure to between 4-7 psi, it is a lot easier on the needle and seat long term. If it exceeds this amount, the needle can be blown off the seat by the excess pressure, and will tend to run really rich especially at idle.

 
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

5590 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 3.703 seconds.   Total Queries: 13   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 10:45 AM
Top