Using original LQ fuel lines with dual tanks?

[EightiesOnly]

I am doing a 2001 5.3 swap into my '86. I am wanting to run an inline fuel pump in front of the dual tanks switch and use the original aluminum fuel lines from the 2001. First, is this going to be possible? Also, are the original steel lines coming from the tanks to the switch going to need replaced with high pressure lines?

In this pic the dark grey would be the steel lines and the silver would be the aluminum lines off of the 2001.



Any suggestions would be appreciated. This is how I've been running it for four years with a low pressure inline pump and low pressure hose running to a 350 TBI. Also, the main reason for wanting to do this is because I'm in college and have a minuscule budget.

[BR3W CITY]

Most of the aluminum hard line I've seen really isn't ideal for high pressure fuel injection; stock lines would be steel and plastic, unless you already changed it out for braided line with aluminum fittings.

I haven't attempted this exact maneuver, but there are some issues with what I see;
A single inline pump will be working very hard to draw the fuel from the tank, as the distance from pickup to pump will be longer than ideal. Additionally, most of the plumbing related to the switch will not be rated for high psi. All the little rubber hoses will need to be swapped for fi-rubber or braided line, with the correct clamps etc.

I also don't see any provision for a return line, which would still be in use on truck engines in 2001.

If I were to attempt this, I would probably do it one of two ways;
1. I would do it "diesel style" i.e., more like how the big-truck boys do it. You run an in tank pump as a "lift" pump to get the fuel out of the tanks and up through the switch, then run another (correctly rated) pump after the switch to keep psi on the fuel rail. This means 3 fuel pumps....which ain't cheap, but means you never starve a pump, and the main pump will always be able to supply enough pressure to the rail. This also creates an issue of things like; where do you put the filter(s), how do you wire it, and how to position and plumb it so you don't create excess cavitation in the lines.

2. Skip the main pump, and run a pair of in-tank pumps to the switch. This still means two pumps, but with some relays and the proper wiring, it can be done just the same. This is cool beceause you get redundancy of parts if you ever need it. Each pump has to work a touch harder than with the lift pump setup, but a pair of correctly rated pumps should have no issues.

Neither way is 100% ideal, but both would be the direction I would look. I personally don't think a single pump would be happy doing that work...UNLESS you can find a BIG single pump that has good draw capability, or go with a crazy engine driven pump which will cost twice what the truck is worth, and probably just be a hassle.

[EightiesOnly]

Thanks for the advice.

First, I thought the 2001 lines were aluminum just because they look like it. Also, the return will probably be high PSI (or low if possible?) rubber hose straight to the switch.

I've also seen aftermarket high pressure switches on here, but the hose on the switch could be changed to high PSI.

Last, do the high PSI pumps work harder than the low PSI? I've ran an inline in front of the switch for four years with Zero issues. I figure if you have to change the pump every 5 or 6 years that's not too bad.

[BR3W CITY]

Originally Posted by EightiesOnly

Thanks for the advice.

First, I thought the 2001 lines were aluminum just because they look like it. Also, the return will probably be high PSI (or low if possible?) rubber hose straight to the switch.

I've also seen aftermarket high pressure switches on here, but the hose on the switch could be changed to high PSI.

Last, do the high PSI pumps work harder than the low PSI? I've ran an inline in front of the switch for four years with Zero issues. I figure if you have to change the pump every 5 or 6 years that's not too bad.

Low psi line isn't safe anywhere on an FI truck, even though the return side is lower pressure than the feed, its still considered high pressure.

Its hard to say if they work "harder"....I mean they use the same 12v power, just draw more current. They have a harder time drawing fuel up, as I mentioned, because they have a higher pressure demand to meet. The biggest issue with putting the pump in front of the switch is that you create a long path from the pickup to the inlet on the fuel pump. That distance usually means the pump has to work harder than it should to get its fuel supply (like sucking through a long straw). This will decrease the life of the pump because it uses the fuel as its cooling source as well.

[Hail]

Im fixing to start a 5.3 swap and was thinking of doing things exact same thing. As long as your "pulling" fuel from the tank to the pump then there's no "pressure" till after the pump. Just use the appropriate line from the pump forward. In my case there is no return on the rail so I thought just running a vette FPR filter, and plumbing return back into factory return. As far as strain on fuel pump from placement, run a good walbouro pump and should be no problems. My Cummins is set up like that and makes around 450hp and my pump is mounted mid ways down the frame. And I have roughly 150k miles on the same pump. No problems ever. But as always. Just my ..02

[EightiesOnly]

Originally Posted by Hail

Im fixing to start a 5.3 swap and was thinking of doing things exact same thing. As long as your "pulling" fuel from the tank to the pump then there's no "pressure" till after the pump. Just use the appropriate line from the pump forward. In my case there is no return on the rail so I thought just running a vette FPR filter, and plumbing return back into factory return. As far as strain on fuel pump from placement, run a good walbouro pump and should be no problems. My Cummins is set up like that and makes around 450hp and my pump is mounted mid ways down the frame. And I have roughly 150k miles on the same pump. No problems ever. But as always. Just my ..02

Thanks for the input, and I agree with you.

I'll probably only use a few feet of the original lines coming from the engine with all the rest being high pressure hose. I'm also running a factor filter from an LS And yes, I'm running a Walbro, not sure on the model #.

[BR3W CITY]

Originally Posted by Hail

Im fixing to start a 5.3 swap and was thinking of doing things exact same thing. As long as your "pulling" fuel from the tank to the pump then there's no "pressure" till after the pump. Just use the appropriate line from the pump forward. In my case there is no return on the rail so I thought just running a vette FPR filter, and plumbing return back into factory return. As far as strain on fuel pump from placement, run a good walbouro pump and should be no problems. My Cummins is set up like that and makes around 450hp and my pump is mounted mid ways down the frame. And I have roughly 150k miles on the same pump. No problems ever. But as always. Just my ..02

Over 18" away and you start to GREATLY increase the wear on the pump. The 255lph walboroughs survive "pull" better than most others, and even so, they do not recommend going too far from the pickup point. There IS a reason that in-tank pumps are the most common from the manufacturers, and its not cost. The pump needs fuel to cool, and drawing it farther means more heat and strain on the pump. Only time you can get away with a large distance from the pickup, is if the tank is higher than the fuel pump, and you gain the gravity advantage to keep fuel against the pickup point.

Fuel pressure on the lines of a cummins truck is only about 14psi, so its not really the same thing. Low psi pumps can run a huge amount of suction. The cummins doesn't get high fuel pressure until AT the injectors.

[Hail]

Originally Posted by BR3W CITY

Over 18" away and you start to GREATLY increase the wear on the pump. The 255lph walboroughs survive "pull" better than most others, and even so, they do not recommend going too far from the pickup point. There IS a reason that in-tank pumps are the most common from the manufacturers, and its not cost. The pump needs fuel to cool, and drawing it farther means more heat and strain on the pump. Only time you can get away with a large distance from the pickup, is if the tank is higher than the fuel pump, and you gain the gravity advantage to keep fuel against the pickup point.

Fuel pressure on the lines of a cummins truck is only about 14psi, so its not really the same thing. Low psi pumps can run a huge amount of suction. The cummins doesn't get high fuel pressure until AT the injectors.

Im running a walbouro 255 inline and its about 5 1/2' from the tank. Running diesel no less. Little thicker than gas.Sure auto manufacturers place them in tank for cooling and durability purposes. And I have mine set at 30# of pressure running into my high pressure pump. So its bypassing a lot of fuel from the regulator back to the tank. Is it a ideal set up, prob not. But works and has been for a long time. And its a pretty common set up in the dodge diesel world. The only problems I could see in using it in "our" application is the amount of return pressure reverted back to the tank. Im just guessing and saying around 10psi? It is free flowing. May be more may be less, but without finding a way to measure it no one really knows. I think it would be safe if it was as much 20# back pressure on the return side. But everyone should be cautious none the less on the return side.

[BR3W CITY]

Originally Posted by Hail

5 1/2' from the tank. Running diesel no less.

This is way too far to recommend to someone for a high pressure fuel system. There isn't a manufacturer in business that would recommend that, and if your sucking through a filter, the draw is even harder

Originally Posted by Hail

And I have mine set at 30# of pressure running into my high pressure pump.

Are you using it as a lift pump to deliver fuel to something like a vp44? Again, this is in no way comparable to a gas engines use of an electronic fuel pump. ..and how are you "setting" the pressure on the pump? The 255lph puts out near 90psi of pressure with full voltage to it.


The amount of pressure on the return side depends on the amount of pressure you try to throw at it vs the amount of pressure the vacuum-fpr requests, taking into account that the pressure itself can be a function of the size of the line. High volume-high pressure fuel IN -> Rail Demand (~58psi) -> Difference in return.

If you have a high fuel supply, with a low demand, your return amount is larger. A larger return amount through a smaller line will create higher pressure, no matter if the line is "open" at the tank end or not.

[Hail]

Its pulling fuel from the tank through a prefilter, out the pump, adjustable FPR, through 2 post pump filters. Water separator, 2micron fuel filter. Into VP pump. Like I said is it ideal...no. Does it work and well...yes. trouble free for 150000 miles and counting. Quality pumps are tougher than people believe. In my humble opinion I believe a 255 pump would run a long time drawing fuel from a carb fuel tank on a lsx swap. AS long as the return restrictions wasn't to great and caused problems.

[BR3W CITY]

Originally Posted by Hail

Its pulling fuel from the tank through a prefilter, out the pump, adjustable FPR, through 2 post pump filters. Water separator, 2micron fuel filter. Into VP pump. Like I said is it ideal...no. Does it work and well...yes. trouble free for 150000 miles and counting. Quality pumps are tougher than people believe. In my humble opinion I believe a 255 pump would run a long time drawing fuel from a carb fuel tank on a lsx swap. AS long as the return restrictions wasn't to great and caused problems.

I get that it works, and I'm not trying to belittle your contribution...but it just doesn't apply here. The differences in the fuel systems for your diesel application and this are not the same demands.

Can you physically draw fuel for his setup that way, Yes, you can.... You can also use compression fittings on brake lines, but its not correct, its not really safe, and its not something we want to pass onto others. In this case, the OP needs the best way to fix/design his fuel system, and by suggesting and defending an improper solution, we aren't helping him in the least.

You can choose to believe me or not, but running a 255 on a long draw is detrimental to the pumps life and overall performance. I'll site source, tell stories, and list qualifications if you want me to, but just believe that I wouldn't write ALL this just to banter on a moot point. From experience 255's don't want to be mounted like that. From experience, they can burn up even under the correct use...why make their life harder/shorter if you can avoid it?

And the return line restriction thing is just a weird point to make. There isn't really anything that can fail in terms of function or system design on the return side, with the exception of size issues from using Meth/E85 due to the huge increase in volume both ways.

[akdg87]

I did 6.0 install in a 1984 K20, we actually were able to put the fuel pump (walbro 255 inline) all the way up on the passenger inner fender. (my buddys choice...) Had the same dual tank setup with the valve, has worked flawlessly.

But if it were my truck and my money, i'd run all AN line and fittings, do it once, do it right,

[doubeys_nova]

i made it a point to have my pump inlet lower than my intank pick-up. a little more distance between tank and pump but i believe that is a much more reliable location. this is because the hardest work is the pump getting the fuel out of the tank. once it does that it is all downhill from there. as far as in the engine compartment that is way above the tank and a lot of suction is required to get the fuel out but the shorter wires makes less resistance and could let the pump last just as long.