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Fuel Pump Plumbing Tutorial

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Fuel Pump Plumbing Tutorial

Old 05-20-2010, 01:42 PM
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Harley Condra
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Default Fuel Pump Plumbing Tutorial

I have read many words regarding this basic task. Some folks know the correct way to accomplish it, and some folks are way off base.
The method that I use is time honoured and well proven.
Safety is a prime concern.

Leaks are the bane of a fuel system...an air leak on the suction side can turn your jet into a glider, and a fuel leak under pressure can turn your jet into a fflying fireball.
I have seen one jet go up in flames during flight from a pressure leak. The result is not pretty.

Another thought...Festo or other brands of "push in" fittings are very convienient...but they are not the best thing on the suction side of the fuel system, in other words, don't use them upstream of the pump. If used on the suction side, any bends in the tubing runs should be of maximum bend radius; sharp bends into a Festo type fitting increase the chances of an air leak.
In order to make a leak proof fuel pump installation, some easy steps must be accomplished.
We will be using polyurethane tubing for this job in both 4mm, and 6mm OD.

First, cut one end of the the 4mm tubing making sure that it is square. No angled cuts allowed. I use a tubing cutter for this job. I used transparent red colored 4mm tubing so it would be more visible in these photographs.

Apply a small amount of Vaseline to the pump fitting, then heat the cut end of the 4mm tubing with a heat gun to soften it. Push the 4mm OD tubing onto the fitting, making sure to bottom it out.

Cut it off flush with the end of the barbed fitting with a sharp razor blade.

Cut the 6mm OD tubing square with the tubing cutter.



Telescope the 6mm OD tubing over the 4mm tubing on the pump inlet fitting, and using .020 Stainless Steel safety wire, double wrap the wire around the tubing, and twist, being sure to pull the wire tight enough to visibly indent the 6mm tubing.

Cut the wire and bend the end over so the sharp end cannot snag fingers, wires etc.

Add the pressure line to the pump using the same method dscribed earlier foer the pump feed line.

This entire operation only takes a few minutes to perform, and will deliver leak-free service for the life of the installation.
Any questions, or clarification required?? I'll be happy to help...
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Old 05-20-2010, 01:51 PM
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KFX450
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Default RE: Fuel Pump Plumbing Tutorial

I have a quick question,

I noticed you were using the polyurethane tubing, hard, stiff,..correct?? Is tygon tubing reliable, in this method, coming from the UAT to the pump??? What are your thoughts??
Old 05-20-2010, 02:12 PM
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Harley Condra
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Default RE: Fuel Pump Plumbing Tutorial

Lots of people use Tygon for their installations, however, Tygon F4040A tubing as purchased at your local hobby shop is smaller ID...it runs .125 ID, versus the 6mm polyurethane, which has an ID of .1575 (20% larger than Tygon).
Tygon works just fine on "small block" engines. I wouldn't even consider it on a high thrust, high fuel flow engine (like a P-180 or P-200), because of it's smaller ID.

The reason that many use Tygon, is that it is usually available locally. The local hobby emporium usually stocks it for the gassers.
6mm polyurethane is available at BVM, Dreamworks, McMaster-Carr, etc. Your local hobby shop doesn't carry it.

Both types of tubing will deteriorate over time with exposure to kerosene, so that's a toss up.
Also, Tygon is soft. I prefer the stronger polyurethane tubing. You must be much more careful when using safety wire on Tygon to avoid cutting it with the wire.

My personal preference is to only use Tygon on the overflow and vent lines. I never use it on any other part of the fuel system.
Old 05-20-2010, 02:16 PM
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Default RE: Fuel Pump Plumbing Tutorial


ORIGINAL: KFX450

I have a quick question,

I noticed you were using the polyurethane tubing, hard, stiff,..correct?? Is tygon tubing reliable, in this method, coming from the UAT to the pump??? What are your thoughts??
I wouldn't use tygon between the UAT and pump. Tygon is soft and can collapse restricting the flow. Use the poly tubing.
Old 05-20-2010, 02:18 PM
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Default RE: Fuel Pump Plumbing Tutorial


ORIGINAL: Harley Condra
avoid cutting it with the wire.

My personal preference is to only use Tygon on the overflow and vent lines. I never use it on any other part of the fuel system.
Same here, but I do use it for the fill line going to the UAT because it gives a better seal on the removable plugs and its more flexible for moving around.
Old 05-20-2010, 02:28 PM
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Default RE: Fuel Pump Plumbing Tutorial

Thanks guys..Exactly what I was looking for. I only have it on the test stand now, but will be changing that set up. I can see how some good suction cold collapse that tubing, and I'm sure the safety wire after time would be digging into it. 6K just in jet and turbine, nevermind everything else, want to make sure everything is right. thank you for taking the time and answering my questions..I really appreciate it..
Old 05-20-2010, 02:35 PM
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Harley Condra
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Default RE: Fuel Pump Plumbing Tutorial

Well, I am glad to be able to pass some hints to anyone that is interested.
That is what this forum is supposed to be used for.
Old 05-20-2010, 07:46 PM
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hooker53
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Default RE: Fuel Pump Plumbing Tutorial

Harley, Very good. Now give us some insight on how you run your new pumps in, that is if you are the type that does this!!! Thanks Roy
Old 05-21-2010, 06:53 AM
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Harley Condra
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Default RE: Fuel Pump Plumbing Tutorial

Roy,

The point of the exercise is to make sure all of the crud and burrs that may be inside the pump are removed, and that the pump gears run free.
If the engine was run by the manufacturer or importer with the supplied pump, it's probably going to be just fine.

If you still consider it to be necessary, here's a way to do it.

Just get a mason jar and fill it half to three qyarters full with mixed fuel (Containg turbine oil or your favorite lubricant).
Attach a line to the intake side of the pump that is long enough to reach the half way point in the fuel level.
Attach a 4mm line to the pump output.
Install a filter in this line, and return the open end of the output line into to the jar. Secure the lines because the pump is a strong little bugger...

The pump will suck fuel from the jar, pass it through the filter and return it to the jar, making a continuous loop.
The filter will catch all of the crud that may be inside the pump during manufacturing.

Hook up a battery to the pump circulating the fuel until the pump runs smooth. If it is not smooth at the start of the process, it will smooth out shortly, indicating that the pump gears were contacting the gear cavity bottom and cover plate too tightly. The steel gears mesh will run in, and they will wear the aluminum housing and cover just enough to sllow the pump to run smoothly.

Old 05-21-2010, 07:10 AM
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hooker53
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Default RE: Fuel Pump Plumbing Tutorial

Harley, Is there any ideal Voltage to do this with?? Thanks for the info. With all the newbees on board this stuff is just great!!! Roy
Old 05-21-2010, 07:48 AM
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schroedm
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Default RE: Fuel Pump Plumbing Tutorial

Can our fuel pumps really collapse a large bore tygon (i.e. 3/16") tube in a 200SX setup??!
Old 05-21-2010, 08:50 AM
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Harley Condra
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Default RE: Fuel Pump Plumbing Tutorial

Roy,
6 volts is easy to do, and the motor will be happy......
Well, some think it is possible for the pump to collapse the tubing.
It sure as heck can't collapse polyurethane.

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