1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

Fuel line question

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Old Mar 20, 2010 | 12:50 PM
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Default Fuel line question

Anyone know the size of the fuel lines on a 1st gen? I noticed the supply is bigger than the return, would it matter if I used the same size for both of them? I need to change mine out at the tank, so i figure I would change it all out. Have found some coils of stainless fuel tubing, just need to know what size I need.

Thanks in advance!
Matt
 
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Old Mar 20, 2010 | 01:35 PM
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i believe it is either 5/16" or 3/8". take a little piece of the hose into your local auto store and theyll be able to tell you what size it is. as for the return being smaller, its fine if its smaller, as most of your fuel is burned through the engine, the need to flow alot of fuel to the return isnt necessary.
 
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Old Mar 20, 2010 | 02:29 PM
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Originally Posted by tltruckparts
i believe it is either 5/16" or 3/8". take a little piece of the hose into your local auto store and theyll be able to tell you what size it is. as for the return being smaller, its fine if its smaller, as most of your fuel is burned through the engine, the need to flow alot of fuel to the return isnt necessary.
WRONG ---
The VE uses fuel to keep it's cool...
The fuel flowing THRU and out the return is cooling the VE. There's not a huge amount flowing but it is necessary. The feed line is 3/8" and the return line is 1/4". You can put 7/16" or 1/2" for the feed but keep the return line.
 
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Old Mar 20, 2010 | 04:32 PM
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Originally Posted by unixcowboy
WRONG ---
The VE uses fuel to keep it's cool...
The fuel flowing THRU and out the return is cooling the VE. There's not a huge amount flowing but it is necessary. The feed line is 3/8" and the return line is 1/4". You can put 7/16" or 1/2" for the feed but keep the return line.
I always was told the stock feed line is 5/16, 3/8 is an upgrade. Leave the return stock as in dont touch it, the VE uses it to aid in its operation and its metered to run with it like that.
 
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Old Mar 20, 2010 | 04:55 PM
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Alright, so I would be good to go with a 1/4" return line, and 3/8" supply line. Cool, thanks for the help! I knew I had to keep the return, just wasn't sure if I could make it the same size as the supply, so I could just buy bulk tubing. No biggie though.

Think I am going to order this this week, along with some more parts.
 
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Old Mar 20, 2010 | 07:01 PM
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It's always a good idea to upgrade the in-tank pickup if you are upgrading the supply line. 3/8 stainless supply line is an excellent upgrade for a 1st Gen. Never worry about it again. But the pickup pulls through a little plastic widget in the bottom the basket that goes through a "less than" 5/16 hole, probably 9/32. So unless you get in there, drill that out a bit and add a 3/8" connection to the bulkhead on the sender top you will not gain any benefit from the larger supply line.

I laugh sometimes reading the posts on various forums about guys that have half inch fuel lines and big pumps but can still "pull it down to zero psi."

Ya think?
 
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Old Mar 20, 2010 | 07:03 PM
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Yeah, I had read about those tubes, aren't there companies that make them? Forgetting the name atm... Draw straw?
 
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Old Mar 20, 2010 | 07:37 PM
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Yes they are draw straws. Made by Vulcan Performance Vulcan Performance - Diesel Bombers

I would leave the return stock. It is plenty large enough for you.
 
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Old Mar 20, 2010 | 07:39 PM
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Cool thanks! Thats the plan at the moment (for the return) and i will do 3/8" supply, while I am there. My power goals aren't insane, just looking to supply it for my HE351ve.
 
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Old Mar 20, 2010 | 07:45 PM
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Originally Posted by tltruckparts
i believe it is either 5/16" or 3/8". take a little piece of the hose into your local auto store and theyll be able to tell you what size it is. as for the return being smaller, its fine if its smaller, as most of your fuel is burned through the engine, the need to flow alot of fuel to the return isnt necessary.
Originally Posted by unixcowboy
WRONG ---
The VE uses fuel to keep it's cool...
The fuel flowing THRU and out the return is cooling the VE. There's not a huge amount flowing but it is necessary. The feed line is 3/8" and the return line is 1/4". You can put 7/16" or 1/2" for the feed but keep the return line.
i know they flow alot of fuel to keep cool, but i was saying there is no need upgrade the return line because you dont need to flow a ton MORE fuel than stock through the RETURN line only. i was implying leave the RETURN stock size. either i typed it confusing or you misunderstood what i meant. sorry for the confusion
 
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