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In or out of tank fuel pumps

wetoolowdingbangow

wetoolowdingbangow

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Ok so I finally got my hands on a tbi setup and im curious to know what the preferred method of fueling is. Fuel pump type, in or out of tank?

Ive heard that an out of tank fuel pump can lose its prime if youre running low on gas or you get real of kilter...is that true? An out of tank pump would be a hell of a lot easier to replace if it came down to it on the trail...

I have a carb setup now with a mechanical pump so I dont have a pump in the tank obviously....is it possible to adapt one inside the tank or does that mean I need a new tank?

If I have to lower the tank again im cutting a whole in the floor and raising it up for clearance and ease of repairs.
 
wetoolowdingbangow said:
Ok so I finally got my hands on a tbi setup and im curious to know what the preferred method of fueling is. Fuel pump type, in or out of tank?

Ive heard that an out of tank fuel pump can lose its prime if youre running low on gas or you get real of kilter...is that true? An out of tank pump would be a hell of a lot easier to replace if it came down to it on the trail...

I have a carb setup now with a mechanical pump so I dont have a pump in the tank obviously....is it possible to adapt one inside the tank or does that mean I need a new tank?

If I have to lower the tank again im cutting a whole in the floor and raising it up for clearance and ease of repairs.
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I have no particular insight into TBI setups, but given your desire for absolute reliability, I would install 2 pumps (with at least one of them being external, obviously). Few things are more irritating than being out and about and having a fuel pump failure. This I have learned from experience. :doah:
I now have an extra external electric (EEE?) fuel pump connected to a switch on the dash board, in addition to my regular mechanical pump. The switch doesn't get flipped very often, but I'm thankful to have it.

External pumps are lots more fun to tinker with on the trail, too. So I vote for at least one external backup pump.

Between pump installations, replacements, filter changes, and a leaky fuel line, I've lost fuel system prime numerous times. I simply run the pump for a few seconds, and it's primed again. Not sure what issues you could have, even if you did lose your prime. :dunno: I'm guessing that your replacement pump would probably be closer to the tank than your current mechanical pump is. So I can't imagine it being worse than your current situation.

TBI tanks have a baffle inside them, IIRC.
 
campfire said:
I have no particular insight into TBI setups, but given your desire for absolute reliability, I would install 2 pumps (with at least one of them being external, obviously). Few things are more irritating than being out and about and having a fuel pump failure. This I have learned from experience. :doah:
I now have an extra external electric (EEE?) fuel pump connected to a switch on the dash board, in addition to my regular mechanical pump. The switch doesn't get flipped very often, but I'm thankful to have it.

External pumps are lots more fun to tinker with on the trail, too. So I vote for at least one external backup pump.

Between pump installations, replacements, filter changes, and a leaky fuel line, I've lost fuel system prime numerous times. I simply run the pump for a few seconds, and it's primed again. Not sure what issues you could have, even if you did lose your prime. :dunno: I'm guessing that your replacement pump would probably be closer to the tank than your current mechanical pump is. So I can't imagine it being worse than your current situation.

TBI tanks have a baffle inside them, IIRC.
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Good to know. I think two pumps would be the way to go. I know a lot of people gravitate towards the walbro ones. I havent put it all together yet so no problems as of yet but im hoping i dont have to get another tank.
 
wetoolowdingbangow said:
Good to know. I think two pumps would be the way to go. I know a lot of people gravitate towards the walbro ones. I havent put it all together yet so no problems as of yet but im hoping i dont have to get another tank.
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Keep in mind that pressures add when pumps are run in series. If you are running 70+ PSI pumps (kinda guessing on the pressure, I don't remember what your TBI setup will run), and you turn them both on at once, they will try to put out 150PSI. Fuel line and couplings may or may not be rated for that. These are problems that us folks down at 7psi don't even think about. ;) But I did want to point that out.

And for the tank thing, I'm curious as to what difference/benefit comes from the baffle.
 
I would keep it OE in design, it works fine.

Then you can carry an inline pump, hose, hose clamps and extra hose in your spare parts bag.
 
skunked said:
I would keep it OE in design, it works fine.

Then you can carry an inline pump, hose, hose clamps and extra hose in your spare parts bag.
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This is a good idea. I installed mine to deal with troubleshooting a specific issue, and to aid in re-priming the 6.2 diesel fuel system (not a fan of the OEM solution here). Since he won't have either of those issues, the need is much less pressing.
 
skunked said:
I would keep it OE in design, it works fine.

Then you can carry an inline pump, hose, hose clamps and extra hose in your spare parts bag.
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So i guess OE is in tank but most kits are out of tank...

I know that ill need a fuel return line into the tank so ill need another sending unit. I wonder if i can put a pump in the tank like OE and then just carry a spare inline fuel pump? It would king of suck to have to buy another tank...maybe mine isnt much different than a tbi tank?
 
IIRC you need a TBI tank, those are baffled. Also make sure you get the correct fuel pump as they're longer or shorter depending on the tank capacity.
 
When I did my TBI swap, everything I read and people I talked to said in-tank pumps are more reliable. Not really sure why, just what I heard. Also, replacing the in-tank is pretty easy as long as you just cut a hole in the floor (if you pay attention to most TBI K5/Burban, most have this hole cut already). If you care to make it look pretty, you can make a little cover to go over it. I just leave mine open and have a big rubbermaid in the back to carry tools/spare parts/fluids that kinda covers it up. It only takes me about 5 seconds to get to the in tank pump now. And I just carry an extra pump with me at all times in that rubbermaid.....easy peasy :)

I am sure you could find a TBI tank at a junk yard or on here from someone for cheap. And yes, the TBI tanks are baffled which helps to make sure the pump doesn't go dry...might just be worth finding a new/used tank and swapping
 
Kay86K5 said:
When I did my TBI swap, everything I read and people I talked to said in-tank pumps are more reliable. Not really sure why, just what I heard. Also, replacing the in-tank is pretty easy as long as you just cut a hole in the floor (if you pay attention to most TBI K5/Burban, most have this hole cut already). If you care to make it look pretty, you can make a little cover to go over it. I just leave mine open and have a big rubbermaid in the back to carry tools/spare parts/fluids that kinda covers it up. It only takes me about 5 seconds to get to the in tank pump now. And I just carry an extra pump with me at all times in that rubbermaid.....easy peasy :)

I am sure you could find a TBI tank at a junk yard or on here from someone for cheap. And yes, the TBI tanks are baffled which helps to make sure the pump doesn't go dry...might just be worth finding a new/used tank and swapping
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I think the pump being in the fuel keeps it cool. I remember I had a 97 sierra that I would dare let go beyond a quarter tank for that reason.

I see rockauto sells an 87 tank for $91. Not bad at all for a new tank. I may as well bring the tank halfway into the bed while im at it so its not hanging down like the stock location...
 
wetoolowdingbangow said:
Hmm. Dremus build just replaced the sending unit...

https://ck5.com/forums/threads/74-k...ammit-rockauto-why-you-do-that.209791/page-24

Maybe theres not much difference between inline and in tank.
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My kit came with an external pump. If you were using factory parts, you'd do ... something different. I donno what the newer trucks use.

I gather the in-tank pumps fail with some frequency, enough that some guys cut an access hole in the floor above the tank to get to it. My tool box is right there, so I opted to stick with the pump on the frame rail.

-- A
 
I chose an in tank setup. There are a few aftermarket universals out there with www.rickstanks.com www.restomodtanks.com getting my money. It's a custom baffled walboro (sp) with an option to add a second. For more power or backup. An in tank will run cooler and longer because of it. I hate fuel problems.

I haven't put everything together just yet but I will do my best to document what I encounter on my install

I will be using the restomod pump in the pass side tank as my primary and use the driver side like a transfer tank. If I don't like how that turns out I may use a blazer tank under the bed but I'd like to leave everything in the oe location.
 
In tank is better.

I have only ever actually seen one truck with an access hole cut in it, my 1990 Blazer, so I don't believe it is that commonly done.

I wish my Blazer did not have an access hole cut in it.

The way you are modifying the rest of this Blazer, you might as well cut an access hole in it.

The baffled fuel tank is better for off road purposes.

Martin
 
I run an external pump back by the tank on my 84 K5. Stock non baffled fuel tank with a full return system. I ran it for 10 years with a TBI 454 and now have a year on a full EFI 454 with no problems at all. Never has overheated the pump and haven't had a problem with low fuel levels. I've had to drop my tank once because the sock on the end of the pickup finally plugged up and that job would suck out on the trail with 30 gallons of gas in it!! I'll stick with an easy to service external pump.
 
82355 said:
In tank is better.

I have only ever actually seen one truck with an access hole cut in it, my 1990 Blazer, so I don't believe it is that commonly done.

I wish my Blazer did not have an access hole cut in it.

The way you are modifying the rest of this Blazer, you might as well cut an access hole in it.

The baffled fuel tank is better for off road purposes.

Martin
Click to expand...

I definitely think the baffle would help with all that sloshing gas. If i go with the in tank route i definitely want an access hole, theres no way i would want to drop a tank out on the trail. Im thinking after i do the 1 inch bodylift i should raise the tank up some and make a real skid for it...

I guess if i have to drop the tank to put a new sending unit in, i may as well have the right tank to begin with.

Anyone with the external pump lose prime before? Seems to me like a working pump shouldn't be able to do that...


campfire said:
Oh, no! There are those words again! This thread is doomed! :doah:



Just another step in the process of having a more lengthy build thread. :pimp:


:haha:
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Lol yeah thats how she goes so far. This whole truck is a box of might as well!
 
I went out of my way to custom make an intank setup for my fuel cell on my street rig. Believe me in tanks are incredibly better. They stay cooler, lower noise, longer lasting, more compact, not in a place to get smashed, etc, etc.
 
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