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[How to:] Siphon fuel using factory fuel pump with no FUSS and no MUSS!

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[How to:] Siphon fuel using factory fuel pump with no FUSS and no MUSS!

 
Old 02-03-2013, 04:36 AM
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JUIC3D
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Default [How to:] Siphon fuel using factory fuel pump with no FUSS and no MUSS!

Hey all,

Here's a quick, easy, and inexpensive way to siphon out fuel from your gas tank without having to fish a hose into your gas tank.

Tools:
  • 6' 3/8 fuel hose: $6 from local auto parts store
  • Shrader valve tool: $5 from local auto parts store
  • 3" 18AWG wire - $1 from anywhere
  • Shop towels or rags

1. Place a handful of shop towels or rags directly below the access port on your fuel rail.

2. Using the shrader valve tool or flat-blade screwdriver, press on the shrader valve to relieve the residual pressure in the fuel rail. There will not be a ton of fuel that comes out, but you will definitely want to have the rags in place.

3. Remove the shrader valve with the shrader valve tool. It unscrews like a regular screw. Make sure the shrader valve tool is completely seated on the valve. The nipple of the valve will be recessed inside of the shrader valve tool.



4. With the shrader valve removed, securely connect one end of the 6' 3/8 fuel hose to the access port of the fuel rail. It should fully seat against the inner edge of the rail.



5. Place other end of 3/8 fuel hose in empty gas can/container.



6. Locate the underhood fuse box(located on the passenger side of the engine bay.

7. Locate relay #55 on the underside of the fuse box cover and remove it.



8. Strip off a 1/2" of insulation from each end of your 3" 18AWG wire.

9. Connect one end of the wire to port #30 (bottom left if you're looking at it from the front of the car) of the relay and the other end to port #87 (top right if you're looking at it from the front of the car). AS SOON as you connect both sides, the fuel pump will begin pumping so BE SURE you have everything in place.



*NOTE* The key does NOT need to be on for the fuel pump to work. Jumping the relay sends battery power straight to the fuel pump, causing it to flow.

10. The stock pump(LS3 at least) flows around 50 GPH so expect it to take a minute or two to fill up a 2 gallon container.



That's it! Hope that helps a fellow drag racer looking to shed a little extra weight in the form of unnecessary fuel. Or, the drag racer looking to add race fuel to the car without mixing with pump gas.
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Old 02-03-2013, 06:07 AM
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thanks good post
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Old 02-03-2013, 07:32 AM
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Good idea!

Be prepared for folks wanting more pics of your helper.
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Old 02-03-2013, 08:00 AM
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Great post! I've been siphoning for years, but it takes a lot of time. I'll try your method next time!
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Old 02-03-2013, 12:11 PM
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You can also disconnect the fuel line at the bulkhead using a quick disconnect and slip the siphon hose over the fuel line. Also, I just wrap small gauge buss wire around the 2 relay contacts/prongs and plug it back in.

BJK
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Old 02-03-2013, 12:35 PM
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^ That's good info too. I just don't like removing the quick disconnect lines very often. That O ring can go bad and the last thing I need is a fuel leak.
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Old 02-03-2013, 01:06 PM
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Thanks for the "how to".

It sounds like a really good way to empty the tank or directly transfer fuel from one car to another. To remove a couple of gallons into a can, I'll stick with the simple siphon method though.
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Old 02-03-2013, 01:16 PM
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Originally Posted by HOXXOH View Post
Thanks for the "how to".

It sounds like a really good way to empty the tank or directly transfer fuel from one car to another. To remove a couple of gallons into a can, I'll stick with the simple siphon method though.
Tom, that's how I do it, but it's tricky to get the siphon hose past the "anti siphon" device in the tank. I tried to walk Justin through it but his hose was too flexible to get past. My clear hose is older, and stiff enough to get past the restriction with just a little fiddling.

omg that statement, while accurate, is full of innuendo. I can't think of a better way to say it however.
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Old 02-03-2013, 01:24 PM
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Originally Posted by JUIC3D View Post
^ That's good info too. I just don't like removing the quick disconnect lines very often. That O ring can go bad and the last thing I need is a fuel leak.
I hear what you are saying. I also have my phobias about jamming a round wire into a socket designed for a blade prong. I would be worried about spreading the contacts to much and reducing the tension that is applied to the relay blades. But that's just me and my forty years experience as an electronics tech.

Thanks for the time you spent to put together this DIY.

BJK
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Old 02-03-2013, 01:33 PM
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Couldn't you have your beautiful helper just turn on the ignition (hit the button without pushing in the clutch) and not fool with the relay at all?
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Old 02-03-2013, 02:48 PM
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Originally Posted by Joe_G View Post
Couldn't you have your beautiful helper just turn on the ignition (hit the button without pushing in the clutch) and not fool with the relay at all?
I could but then I'd have to cycle it on off on off for however long until it emptied the amount I needed.

Originally Posted by 07MontRedcp View Post
I hear what you are saying. I also have my phobias about jamming a round wire into a socket designed for a blade prong. I would be worried about spreading the contacts to much and reducing the tension that is applied to the relay blades. But that's just me and my forty years experience as an electronics tech.

Thanks for the time you spent to put together this DIY.

BJK
Ya, I understand what you're saying and that is why I went with 18 AWG wire. It required 0 effort to put in the slots as it was actually too small to snugly fit in the socket.
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Old 02-03-2013, 07:52 PM
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Not sure whether it makes a difference or not for this purpose but you'll only be pulling fuel from the driver's side tank with this technique. As long as your gauge is 1/2 full or less all of the fuel is in the driver's side tank anyhow though. It takes >50psi in the system for the venturi pump in the right side tank to transfer fuel. With the line open, you'd get nowhere near 50 psi.
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Old 02-03-2013, 07:54 PM
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Good point MH. If you need to drain more than 9 gallons, you can plug the port with the shrader valve and turn the ignition on for a few seconds to let the passenger side tank fill up the driver's side.
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Old 02-03-2013, 07:56 PM
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Originally Posted by Joe_G View Post
Couldn't you have your beautiful helper just turn on the ignition (hit the button without pushing in the clutch) and not fool with the relay at all?
There is a default "Prime Time" of just 2 seconds set in the ECU...configurable up to 410 seconds via HPTuners.
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Old 02-03-2013, 08:22 PM
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I use an old R12 low side AC gauge hose to do this, along with a modified relay that stays energized.

I pump it into a 30 gallon plastic container and use a 12V Carter in line pump to put it back in.
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Old 02-03-2013, 08:27 PM
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Originally Posted by glenB View Post
I use an old R12 low side AC gauge hose to do this, along with a modified relay that stays energized.

I pump it into a 30 gallon plastic container and use a 12V Carter in line pump to put it back in.
Boy the combined knowledge of the forum is amazing.

I have a set of old r12 gauges, I might do that instead of my siphon trick as the siphon trick takes a long time.

I've been concerned about the hose coming off the schrader valve and the ac hose, which screws on, takes care of that concern.
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Old 02-03-2013, 08:29 PM
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3/8 hose is very snug on the threads. The fuel isn't under high pressure with such a large opening in the rail, it just pours out like a garden hose on medium.
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Old 02-03-2013, 08:33 PM
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Originally Posted by JUIC3D View Post
3/8 hose is very snug on the threads. The fuel isn't under high pressure with such a large opening in the rail, it just pours out like a garden hose on medium.
Good point. I guess I could also use a hose clamp if I was that nervous about it.
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Old 02-04-2013, 12:59 AM
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I'd like to add a caution, since this is now a sticky and will be viewed far more often.

Be very careful if you attempt this with a hot engine. Releasing the pressure and removing the valve will allow fuel to spill out. If the rag you use, or if you opt not to use one, doesn't absorb all the fuel, it can easily drop onto the exhaust manifold or headers. Also, once you have finished using the rags, take them out of the engine compartment before you start pumping fuel.
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Old 02-04-2013, 04:41 PM
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Originally Posted by Motorhead-47 View Post
There is a default "Prime Time" of just 2 seconds set in the ECU...configurable up to 410 seconds via HPTuners.
Originally Posted by HOXXOH View Post
I'd like to add a caution, since this is now a sticky and will be viewed far more often.

Be very careful if you attempt this with a hot engine. Releasing the pressure and removing the valve will allow fuel to spill out. If the rag you use, or if you opt not to use one, doesn't absorb all the fuel, it can easily drop onto the exhaust manifold or headers. Also, once you have finished using the rags, take them out of the engine compartment before you start pumping fuel.
Excellent point HOXXOH on the cautionary measures.

---

Motorhead-47 did an excellent write up on tank removal/reinstall in recent pass - which deviated from FSM's lengthy process. I have dropped a few tanks in decades of working on car's fuel system but they were much easier than C6.

Every components has an defined life cycle, thus each time it is energized, it takes that much life out of the component. I would much prefer not having to change out my fuel pump before its time due to unnecessary useage.

If I need gas, I would prefer to get it from the gas station.

Another case of to each his own.

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