LMC EFI gas tank install

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

1low4x4

Full Access Member
Joined
Feb 14, 2011
Posts
2,409
Reaction score
716
Location
Texas
First Name
Nick
Truck Year
1984
Truck Model
K10
Engine Size
5.7
Hey guys, was wondering if anyone had used this tank before. This is an 84 short bed C 10 that was converted from carburetor to TBI and overdrive over a decade ago. Everything was taken from a 94 Chevy van.

The gas tank that was in it has developed holes. I ordered a new one, but I got the EFI style one this time. The last one was the original tank, with an original style fuel hanger, that they I guess put a fuel pump on. It’s still walked into the gas tank with the lock nut.

This one came with limited instructions, it has a hanger, and you can see on the top. The letters R for return, S, for supply, and V for vent.

The long tube is connected to the return, which doesn’t make sense to me, I would think that the fuel pump would need to be connected to the supply line and it would need to be the long one, correct?

Second, any clue judging by the pictures what thread or what type of male fitting I need to go into these female holes? I don’t know why they wouldn’t just put something you could clamp a fuel hose to. Or at least supply that if you decided to go that route.

Third, can I just get any fuel pump from the parts house for a TBI truck? Around the same year?

Thanks for any help.
 

Attachments

  • IMG_6664.jpeg
    IMG_6664.jpeg
    238.3 KB · Views: 110
  • IMG_6663.jpeg
    IMG_6663.jpeg
    123.9 KB · Views: 109
  • IMG_6662.jpeg
    IMG_6662.jpeg
    157 KB · Views: 98
  • IMG_6661.jpeg
    IMG_6661.jpeg
    125.8 KB · Views: 108

1low4x4

Full Access Member
Joined
Feb 14, 2011
Posts
2,409
Reaction score
716
Location
Texas
First Name
Nick
Truck Year
1984
Truck Model
K10
Engine Size
5.7
This is the tank, doesn’t show the correct year but it’s the same thing.
 

Attachments

  • IMG_6665.png
    IMG_6665.png
    279.3 KB · Views: 84

Redfish

Full Access Member
Joined
Nov 6, 2021
Posts
2,658
Reaction score
14,316
Location
Prairieville, LA
First Name
Andrew
Truck Year
1987
Truck Model
V1500
Engine Size
350/5.7
If your motor is stock or close to stock the fuel pump for a 1987 TBI will be fine. If you have a lot more horsepower there are some fuel pumps that flow more than the OE pump. If you check the Harristuning website he recommends a better pump for more horsepower and he tells you how much horsepower the standard pump can feed.
 

1low4x4

Full Access Member
Joined
Feb 14, 2011
Posts
2,409
Reaction score
716
Location
Texas
First Name
Nick
Truck Year
1984
Truck Model
K10
Engine Size
5.7
If your motor is stock or close to stock the fuel pump for a 1987 TBI will be fine. If you have a lot more horsepower there are some fuel pumps that flow more than the OE pump. If you check the Harristuning website he recommends a better pump for more horsepower and he tells you how much horsepower the standard pump can feed.
Thanks redfish! The motor is close to stock. Flat top pistons and a mild cam but not a power house.
 

hogdaddy

Full Access Member
Joined
Jan 12, 2023
Posts
127
Reaction score
237
Location
Alabama
First Name
mike
Truck Year
1986
Truck Model
Scottsdale
Engine Size
350
The supply line line gets the in-tank fuel pump, pick/up and a length of rubber hose I am guessing since it (filter) need to be positioned at the very bottom of tank
 
Last edited:

vr1967

Full Access Member
Joined
Apr 16, 2023
Posts
229
Reaction score
791
Location
Mississippi
First Name
Virgil
Truck Year
1984
Truck Model
k1500
Engine Size
6.2L turbo
I would put in a 96-97 pump in it from a Vortec equipped truck. (Ep381) It has twice the flow of the tbi (ep386) pump
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
4,194
Reaction score
8,034
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
I would put in a 96-97 pump in it from a Vortec equipped truck. (Ep381) It has twice the flow of the tbi (ep386) pump
TBI was long gone by 96. The EP381 is way too much pressure unless you have true "multiport" EFI.
 

vr1967

Full Access Member
Joined
Apr 16, 2023
Posts
229
Reaction score
791
Location
Mississippi
First Name
Virgil
Truck Year
1984
Truck Model
k1500
Engine Size
6.2L turbo
TBI was long gone by 96. The EP381 is way too much pressure unless you have true "multiport" EFI.
The ep381 pump has an internal bypass spring that makes it capable of producing higher pressures, but the regulator is in the tbi unit itself, which regulates pressure from 11-18psi depending on spring color, unless they have a 94-95 454/7.4 spring, which will then make the pressure about 34psi. Pressure is set by the regulator.

Just because a pump is capable of producing the pressure doesn’t mean it will.
 
Last edited:

Redfish

Full Access Member
Joined
Nov 6, 2021
Posts
2,658
Reaction score
14,316
Location
Prairieville, LA
First Name
Andrew
Truck Year
1987
Truck Model
V1500
Engine Size
350/5.7
I copied this from the Harris Tuning TBI website.


1. First I start with a new Fuel pump, STOCK 75lph TBI fuel pump will only support about 230hp before the fuel pressure drops like a rock. I recommend upgrading to the 1996 Vortec 155lph fuel pump which can support up to 450hp and plugs right into a factory TBI sending unit. https://www.summitracing.com/parts/ado-ep381 So I begin every project with a new upgraded pump.
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
4,194
Reaction score
8,034
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
Hey guys, was wondering if anyone had used this tank before. This is an 84 short bed C 10 that was converted from carburetor to TBI and overdrive over a decade ago. Everything was taken from a 94 Chevy van.

The gas tank that was in it has developed holes. I ordered a new one, but I got the EFI style one this time. The last one was the original tank, with an original style fuel hanger, that they I guess put a fuel pump on. It’s still walked into the gas tank with the lock nut.

This one came with limited instructions, it has a hanger, and you can see on the top. The letters R for return, S, for supply, and V for vent.

The long tube is connected to the return, which doesn’t make sense to me, I would think that the fuel pump would need to be connected to the supply line and it would need to be the long one, correct?

Second, any clue judging by the pictures what thread or what type of male fitting I need to go into these female holes? I don’t know why they wouldn’t just put something you could clamp a fuel hose to. Or at least supply that if you decided to go that route.

Third, can I just get any fuel pump from the parts house for a TBI truck? Around the same year?

Thanks for any help.
The return is the long tube. This is so returning fuel doesn't "dump" on top of the fuel level and aerate creating bubbles. The short tube on the one marked S is also correct. That is where the fuel pump will connect with a short piece of hose. That's an odd looking pickup. Normally there's a metal bracket that extends down that the fuel pump sits on (directly below the short tube). If you have factory TBI, I would get a pump for a 87-91 application. Photo attached for reference.

I'll be honest, I went from carb to Multiport EFI on a return style system. I used all factory stuff for an 87 to replace all my 85 parts. I skipped over the TBI technology so I may not be up to date on the nuances of that system.
 

Attachments

  • pickup.PNG
    pickup.PNG
    98 KB · Views: 71
Last edited:

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
4,194
Reaction score
8,034
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
The ep381 pump has an internal bypass spring that makes it capable of producing higher pressures, but the regulator is in the tbi unit itself, which regulates pressure from 11-18psi depending on spring color, unless they have a 94-95 454/7.4 spring, which will then make the pressure about 34psi. Pressure is set by the regulator.

Just because a pump is capable of producing the pressure doesn’t mean it will.
ok
 

1low4x4

Full Access Member
Joined
Feb 14, 2011
Posts
2,409
Reaction score
716
Location
Texas
First Name
Nick
Truck Year
1984
Truck Model
K10
Engine Size
5.7
I’m having hell finding the male fittings with barbed ends, or any other end on it to fit into these female holes. I’ve been to three parts houses, and four hardware stores, found out it’s metric not standard. I’m going to email MC . This is ridiculous that they don’t give you fittings for these to mate to something else.

I bought a fuel pump from a 96 Vortec for it.
 

hogdaddy

Full Access Member
Joined
Jan 12, 2023
Posts
127
Reaction score
237
Location
Alabama
First Name
mike
Truck Year
1986
Truck Model
Scottsdale
Engine Size
350
I’m having hell finding the male fittings with barbed ends, or any other end on it to fit into these female holes. I’ve been to three parts houses, and four hardware stores, found out it’s metric not standard. I’m going to email MC . This is ridiculous that they don’t give you fittings for these to mate to something else.

I bought a fuel pump from a 96 Vortec for it.
That will be tough to find metric but they are available. This is for 10mm and there is other sizes.
 
Last edited:

Forum statistics

Threads
44,182
Posts
950,981
Members
36,305
Latest member
KennedyGS
Top