Pre-pump mod stumper.
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
Pre-pump mod stumper.
Ok folks, was under the truck today surveying the fuel lines and just looking around to size up the in-tank/prepump mod for a PITA estimate. I noticed that my fuel line from the tank all the way up to about 16" from the pump is all steel except for a 16" section of hose? Wasn't I supposed to be looking for a quick disconnect o-ring style section somewhere there or is it between the pump and engine where there is some type of fitting/clip type connection. And that 16" section of hose is just slipped on with no clamps. Could the previous owner have done this and had a filter there or are some just like this? I bought the truck in 02.
Last edited by Tenn01PSD350; Mar 4, 2006 at 09:29 PM.
Post Fiend
Joined: Jul 2005
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From: 21791
i i know that there is a QD connection on the inlet side of the pump, one at the top of the tank, and i think there is one that connects the metal line to the tank via a rubber hose. i think there are three total.
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
That's what I thought but not what I saw. Of course with the exception of the top of the tank. What I could see right up to where the line goes above the tank is a solid steel lin and the hose already mention right at the pump???
Don't worry, be happy? At least until I drop the tank and look up top anyway.
Don't worry, be happy? At least until I drop the tank and look up top anyway.
Lead Driver
Joined: Oct 2004
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From: Columbia, MO
Originally Posted by strokin_it7.3
i i know that there is a QD connection on the inlet side of the pump, one at the top of the tank, and i think there is one that connects the metal line to the tank via a rubber hose. i think there are three total.
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
No pics right now JT, still got about a half a tank in there so not even toying with the idea of dropping it this weekend. I will go out there with a flashlight and look for the QD at the pump cause now it's bugging me.
On edit: You guys are right. It is just pushed on one end and there is a QD right at the pump, just like you described JT. My exhaust is gonna have to wait for this fuel situation. Thanks.
On edit: You guys are right. It is just pushed on one end and there is a QD right at the pump, just like you described JT. My exhaust is gonna have to wait for this fuel situation. Thanks.
Last edited by Tenn01PSD350; Mar 4, 2006 at 10:46 PM.
Posting Guru
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Tenn, there are quick disconnects between the fuel pump and the engine - but don't worry about those. The QDs are designed to seal under pressure AND since the fuel at this point is pressurized, there can't be any air sucked in.
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
Hey I appreciate that. But that leads me to another question because I suffer from over ****yzation. Many here that have gone to a regulated return have pointed out that they leave an orifice or some other provision in order to allow the system to bleed off pressure when not running. If this works as advertised, could air not get in those fittings? Maybe when I finally get to doing something instead of all this postulating I'll just eliminate all Qds.
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Lead Driver
Joined: Oct 2004
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From: Columbia, MO
Are you talking about the fittings on our regulated return systems? All of the fittings I used are air tight, none of them are QD's. Plus, the whole system is under pressure. The air comes from getting into the QDs that are under a vaccum, thus the need to only eliminate them pre pump. And there's no way for air to get into the orifice. The orifice is almost at the very top of the fuel system, and nearly the last step in the fuel lines, so any air that may be in there will be gone in just a few seconds once the pump kicks on. The orifice is constantly under pressure when the truck is running.
Maybe I don't understand what you're asking.
Maybe I don't understand what you're asking.
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
No not at all JT. Your system is the model I am currently working on gathering the hardware and putting on my truck. I'm referring to the QDs that are between the pump and the engine fuel filter. Sorry for the mix up. I just don't have any use for a QD anywhere in the supply line if I'm going through all this trouble to eliminate air. But while we're at it, does the stock system bleed down pressure when not running and how? Hope you're feeling better and off the couch. Mike
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Originally Posted by Tenn01PSD350
I'm referring to the QDs that are between the pump and the engine fuel filter. Sorry for the mix up. I just don't have any use for a QD anywhere in the supply line if I'm going through all this trouble to eliminate air.
Actually, the QDs were designed to seal with positive pressure. They weren't designed to seal under negative pressure (suction), which is why they can be problematic in the pre-pump fuel line.
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Post Fiend
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From: Middle Tennessee
Originally Posted by arninetyes
The fuel line from the pump to the fuel filter is under positive pressure (hopefully more than 60psi), not suction. If the QDs leaked here, they wouldn't allow air in, they would leak fuel out. You can replace them if you want, but it won't make any difference - unless they ARE leaking fuel, that is!
Actually, the QDs were designed to seal with positive pressure. They weren't designed to seal under negative pressure (suction), which is why they can be problematic in the pre-pump fuel line.
Actually, the QDs were designed to seal with positive pressure. They weren't designed to seal under negative pressure (suction), which is why they can be problematic in the pre-pump fuel line.
Lead Driver
Joined: Oct 2004
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From: Columbia, MO
Originally Posted by Tenn01PSD350
But while we're at it, does the stock system bleed down pressure when not running and how? Hope you're feeling better and off the couch. Mike
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Post Fiend
Joined: Feb 2006
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From: Middle Tennessee
Originally Posted by jtharvey
Yes, the stock system does bleed pressure down. The stock FPR has holes in it the cap that holds the spring and plunger in place. It's through these holes that the fuel returns to the tank. Due to the design of the factory FPR providing pressure by just the use of a spring and those small holes, when the fuel pump is shut off, the pressure is easily bled out as the spring relaxes.
