Cummins 4BT & Diesel Conversions Forums banner
1 - 20 of 22 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter · #1 ·
I recently did a 4bt swap with the VE injection pump and a mechanical lift pump. I am having trouble starting with the fuel lines I used because they’re collapsing. Does anybody have a good recommendation for fuel lines that won’t restrict my flow? I’m running 3/8 line.
 

·
Premium Member
Joined
·
1,000 Posts
They should not collapse unless there is a restriction in the line/pickup. Any good hydraulic hose should hold up fine.
That said I used 1/2" OD hard Nylon tubing for my lines.
Cheers Steve
 
  • Like
Reactions: SUBRUTUS

·
Registered
Joined
·
22 Posts
Discussion Starter · #3 ·
They should not collapse unless there is a restriction in the line/pickup.
It’s a brand new tank, new pickup, new filter, etc, there are no restrictions. I think the line I got is just too pliable, I’m looking for a recommendation for a stiffer one.
 

·
Registered
Joined
·
1,728 Posts
I agree with Blackduck, the fuel hose should not collapse. Are you using surgical tubing? Do you have have sharp bends in the hose?

I have 3/8" nylon fuel line in my 4bt powered F150.

Recommendation: For your splices, use fuel injection rated hose, it holds up to modern fuel additives.

Russ
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #5 ·
I agree with Blackduck, the fuel hose should not collapse. Are you using surgical tubing? Do you have have sharp bends in the hose?

I have 3/8" nylon fuel line in my 4bt powered F150.

Recommendation: For your splices, use fuel injection rated hose, it holds up to modern fuel additives.

Russ
Can you send me a link to the fuel line you used? I just got generic fuel line from Napa.
 

·
Registered
Joined
·
1,728 Posts
That was 9 years ago. Autozone can order it in 10 foot or 25 foot rolls.


Generic rubber fuel line is not going to collapse under ordinary usage. I only can think of a few options.

1. A kink in the fuel line - usually caused by a bend that has too tight a radius. I managed to kink my nylon fuel return line at the fuel tank - It took me a while to figure that one out.

2. Some body part pinching the fuel line shut.

Visually inspect the entire length of the fuel line for 1 and 2.

3. Something at the tank blocking the fuel flow
a. Fuel pickup tube hitting the bottom of the tank and restricting the fuel flow
b. Stock fuel filter sock not removed from the pickup tube (Diesel plugs up the original gas filter sock)

4. Crap from your tank plugging up the fuel filter (did you remove the tank and clean it)

5. A chunk of something in the fuel line. 1964 - I worked in a gas station and the pickup truck would not climb up the big hill outside of town. Got enough fuel to drive around town. They eventually found a small chunk of rubber in the fuel line - it restricted the flow. It stumped our best mechanic for a while.

Russ
 

·
Registered
Joined
·
246 Posts
JUST A THOUGHT; In my AO wasps have been known to place their mud nest inside of small diameter hoses...we call them MUD PLUGS, hope this is not your problem..
 

·
Administrator
Joined
·
4,179 Posts
Improperly vented tank or fuel filler cap not vented? Test by removing fuel filler cap.
 
  • Like
Reactions: Blackduck596

·
Registered
Joined
·
22 Posts
Discussion Starter · #9 ·
That was 9 years ago. Autozone can order it in 10 foot or 25 foot rolls.


Generic rubber fuel line is not going to collapse under ordinary usage. I only can think of a few options.
Great advice from all on here. I ordered the nylon tube to try that out. I’m concerned the guy at Napa gave me something not intended for fuel. I can see the length of fuel line is in an oval shape even when I disconnected it from the lift pump so something is wrong. The tank is brand new, new pickup, fresh diesel, straight run, etc. 0 hours on the system.
 

·
Registered
Joined
·
1,728 Posts
Maybe a little more information on the "fuel line".

Is it a clear plastic hose or a rubber hose?

What is printed on the hose?

I remain skeptical that a functional tank/pickup combination will produce enough vacuum to collapse a fuel hose.

Too many unknowns - Consider starting your diesel from a portable tank, located under the engine. Use a length of flexible fuel line from the suction side of the mechanical lift pump to the portable tank. Once you get the diesel running correctly, trouble shoot your way back to the tank.

Russ
 
  • Like
Reactions: SUBRUTUS

·
Registered
Joined
·
22 Posts
Discussion Starter · #11 ·
Maybe a little more information on the "fuel line".

Is it a clear plastic hose or a rubber hose?
I replaced the fuel line, which said “fuel line” on it with the hard nylon line and it is working well now. When I removed the rubber fuel line it had a permanent collapsed oval shape to it. I have to assume the line is only intended for in tank fuel pumps that create pressure rather than suction.
 

·
Registered
Joined
·
1,728 Posts
Glad it works - I'll have to make a mental note.

"Every day is a school day" Gene Winfield
 
  • Like
Reactions: SUBRUTUS

·
Registered
Joined
·
1,728 Posts
What fittings does one use with such nylon tubing?
I use a short length of rubber fuel hose at each end (the low pressure fuel injection hose lasts longer). It is a tight (force) fit. clamp with the fuel injection fuel hose clamps.

Russ

EDIT: The rubber fuel hoses are now 9+ years old - I probably should crawl under there and install new hoses.
 
  • Like
Reactions: SUBRUTUS

·
Registered
Joined
·
463 Posts
I use a short length of rubber fuel hose at each end (the low pressure fuel injection hose lasts longer). It is a tight (force) fit. clamp with the fuel injection fuel hose clamps.

Russ

EDIT: The rubber fuel hoses are now 9+ years old - I probably should crawl under there and install new hoses.
So, the rubber hose slips right over the nylon. Cool.

I always cut an "access port" in the bed...over the fuel sender. So, work on those hard-to-get-to fuel hoses and the sender is easy.

Roy
 

·
Premium Member
Joined
·
1,000 Posts
That hose has it's own fittings but easy to assemble a crossover to standard hose fittings or directly to anything with threaded fittings.
Cheers Steve
 

·
Registered
Joined
·
75 Posts
The fuel hose that I use on everything these days is "Emissions Barrier EFI Fuel Hose". Different mfg's will term it different;y, but the clue is that this hose has a smooth liner that looks like it could be clear to white polyethylene.
 
  • Like
Reactions: Russ McLean

·
Premium Member
1989 Jeep Wagoneer, 360v8, 727, stock for now,
Joined
·
2,719 Posts
The most common fuel line for Diesel and gasoline is SAE 30R6
From Continental Industry
Specially designed low-pressure hose for gas and gas/ethanol blends in carbureted vehicle applications. Resists gas, oil and diesel fuel. (Not recommended for use with biodiesel – see 30R9.)

  • Reinforcement: Two-spiral polyester
  • Temperature range Up to 212 °F (100 °C)
  • Specially designed for gas, oil, diesel and other fuels
  • Minimum Burst 175 psi (1.2MPa)
  • Meets and exceeds SAE J30R6 specifications
  • Warning: Do not use for pressure line on fuel-injected engines.
 

·
Registered
Joined
·
106 Posts
I recently did a 4bt swap with the VE injection pump and a mechanical lift pump. I am having trouble starting with the fuel lines I used because they’re collapsing. Does anybody have a good recommendation for fuel lines that won’t restrict my flow? I’m running 3/8 line.
There should be a 1 way valve ( check) in your fuel pump to stop it from trying to pump out of the output side.. this may sound stupid.. but are you plumbed out of the fuel pump outlet to the Injector pump?... Sorry i had to ask.. if your fuel pump is flowing correctly and the check valve is operating properly it should keep the fuel line inflated... BUT ( Big But) if I remember correctly some Fuel injection pumps also have internal fuel pumps and draw.. if this is happening and your fuel pump isn't keeping up volume with the injector pump.. your fuel line will collapse... .. so check both pressure and flow on the output side.. and watch the gauge .. is it is bouncing from nothing to presure ..chances are your injection pump has a higher draw than your fuel pump output..
 

·
Premium Member
Joined
·
1,000 Posts
There should be a 1 way valve ( check) in your fuel pump to stop it from trying to pump out of the output side.. this may sound stupid.. but are you plumbed out of the fuel pump outlet to the Injector pump?... Sorry i had to ask.. if your fuel pump is flowing correctly and the check valve is operating properly it should keep the fuel line inflated... BUT ( Big But) if I remember correctly some Fuel injection pumps also have internal fuel pumps and draw.. if this is happening and your fuel pump isn't keeping up volume with the injector pump.. your fuel line will collapse... .. so check both pressure and flow on the output side.. and watch the gauge .. is it is bouncing from nothing to presure ..chances are your injection pump has a higher draw than your fuel pump output..
Go back and check the OP's post #11, he has solved his problem.
 
1 - 20 of 22 Posts
Top