Fuel Fuel Pump Rewire, New Fuel Lines, and Installation of New Fuel Pump Hanger with AN6 Connections


lube between the nut and the face
Founding Member
Oct 28, 2001
Claremore, OK
So I wired in a secondary relay a long time ago when I switched to a Walbro GSS340 255 lph pump but it was pretty much all on the stock wiring. I have finally started the laundry list of things that need to be addressed on the Coupe and upgrading the wiring on the pump is at the top of the list being I am starting to push the pump with the 331 putting down a little over 460 fwhp. Tuner had to bump the base fuel pressure up to feed the motor in the 5,000+ rpm range and told me any more and it needed more pump. This caused me to go down a lot of rabbit holes doing research which lead me to a few YouTube videos.

I cam across this guy and what he was saying made sense:

View: https://www.youtube.com/watch?v=lEYD5-plOUs

I then found this video by Pro-M which sealed the deal as I could see what the guy above was talking about:

View: https://www.youtube.com/watch?v=3osqtEtIEig

I am going to do the flexible fuel line extension on the stock hanger as I am still running the stock fuel lines. And speaking of the stock fuel lines I did some research there as Pro-M brings up the fact that the 1/4" return starts to become a restriction with a 255 lph pump. I do not see the pressure come up at idle on my car and I am running a full sweep Autometer electric gauge and it stays at 45 psig through a full pull in 4th on the dyno. I think with the short lines he was running and no engine consuming fuel is what contributed to that. I also noodled around and there are cars making 600+ fwhp on stock fuel lines so I am not messing with them. —-See Posts #8 & #12 as I changed my mind on this.—-

So to get this done I have ordered or bought locally the following:

(1) Fuel pump hanger lock ring and seal from AutoZone - Spectra Premium Fuel Tank Lock Ring, P/N LO03
(1) Fuel tank filler neck grommet from AutoZone - Spectra Premium Fuel Filler Neck Seal, P/N FNA03
(1) Fuel pump to hanger S hose from Walmart (quicker shipping) - Quantum P/N HFP-RH2
(1) Walbro GSS340 sock filter (strainer) from www.walbrofuelpumps.com - Walbro P/N 125-157
(1) Walbro GSS340 replacement electrical connector plug from Amazon - Ballenger Motorsports P/N CONN-76039 (fits 10-12 ga wire)
10 ga PTFE jacketed wire - Mar Vac Electronics (10' of black and 10' of orange)
(2) Rubber grommets 3/16" ID from Lowes - Lowes Item #423561
24" of 1/4" rubber fuel line from O'Reillys - Gates P/N 27002 (Gates website says good for all gasoline blends and E85) —-won’t be using this now, see Post #8 & #12—-
(1) 30A Bosch relay - I bought a lot of 30 a few years ago and still have some left so I’m going to replace the one I put in years ago.

New stuff due to going to a different hanger and upgrading the fuel lines:
(1) Pro-M fuel pump hanger with 3/8" fuel lines and 6AN fittings - Pro-M P/N HANG
(2) 25' lengths of 3/8" plastic fuel line from Amazon - Dorman P/N 800-072
(2) 5/8"(16mm) ID Heat Shielded Fire Thermo Armor Fire Sleeve Silicone Coated Fiberglass for Automotive Hose Lines & Electrical Wiring Black, 5 feet - BSTFLEX P/N FIRES16MM
(1) 3/8" ID Black Silicone Coated Fiberglass Heat Shielded Sleeve Fire Thermo Armor for Hose Lines & Electrical Wiring, 5 Feet from Amazon - KRD Performance M/N HSA-10-5_BK
(2) 6AN Male to 3/8" SAE Quick Disconnect Male Push On EFI Fitting Adapter Aluminum from Amazon - Evil Energy No P/N
(2) -6AN Female to 3/8 Male EFI Adapter from Amazon - Fragola P/N 491995
(1) Fuel Line Straight Quick Connector - Adapts 3/8 In. Steel To 3/8 In. Nylon Tubing from Amazon - Dorman P/N 800-082.5 (box of 5)
(1) Fuel Line 90 Degree Elbow Quick Connector - Adapts 3/8 In. Steel To 3/8 In. Nylon Tubing from Amazon - Dorman P/N 800-086 (single)
(1) 3/8" Fuel Filter (quick disconnect on both ends) - WIX P/N 33243, Good for 75 psig
(1) 3/8" Inch Stainless Steel Cable Clamp, Rubber Cushioned Insulated Clamp from Amazon - Lokman P/N LK-88 (20 Pack)
(1) 3/4" Inch Stainless Steel Cable Clamp, Rubber Cushioned Insulated Clamp from Amazon - Lokman P/N LK-88 (20 Pack)

So the plan is to remove the orange rubber nipple from the 1/4" return line on the fuel pump hanger and add about 12" of 1/4" rubber line to the hard line with a clamp. When the pump goes back into the tank I will use a long screw driver or whatever to guide the hose outside of the slosh baffle that the pump sits in. If it is a pain in the rear then it will go inside the baffle. —- See Post #8 and Post #12 as I changed my mind on this...twice—-

I watched a few videos of increasing the wire gauge size to the pump and this guy always cracks me up and he had a video on it. About the only thing I am using from his video is drilling the rivets on the factory white connector and running the wire through those holes. Watch the rest of the video at your own peril...

View: https://www.youtube.com/watch?v=TR-3SRXWuRI

Most of the videos reused the wires on the hanger which I do not want to do. I am going to use his trick on drilling the rivets, enlarging the holes for 0.1875" ID grommets, and passing the 10 ga wire through them. If the wire is a tight fit through the grommets a little dish washing liquid may be in order. The PTFE jacket on the wire will be really slick so it may pass right through. Did a bit of reading on what to seal the grommet and wire to the hanger and the resounding answer was two-part epoxy. I plan on covering the entire grommet as they are just rubber and the gasoline will eat them up over time. I am only using them for chaffing on the wire so covering them top and bottom with the epoxy is not an issue. I am also going to cover the end of the crimp connectors that go into the fuel pump connector with the epoxy as I do not want fuel to migrate up the wire. This will get the pump installed into the tank and next will be getting the wires into the trunk.

I will be installing a Delphi Weatherpack connector so that I have a quick disconnect under the car to get the tank out. Just in case someone does not know what a Weatherpack connector looks like (finding a smaller image was taking too long):


I will use the 12V+ and ground in the stock wiring harness to trigger the 30A Bosch relay that will be mounted in the trunk. The relay will be mounted behind the panel that covers the rear tail lights and I will ground the pump at the same location. I will run a 10 gauge wire from the battery back to the relay and fuse it up by the battery with a 15 amp fuse and see if the inrush when the pump starts pops that or not. Most say that they have 10 amp fuses and have no issue but all the new wiring will support more than 15 amps so things should be safe.

The whole idea behind this is to keep the voltage as high and steady at the pump as possible. With the age of the wiring on the car, the factory power wire being 14 gauge, the power wire passes through five connectors. Power starts at an 18 gauge fusible link that is at the starter solenoid on the inner apron, goes to the fuel pump relay, then to a connector in the passenger kick panel, then to a connector in the driver kick panel, then the inertial switch connector, then the disconnect plug between the body harness and the tank harness under the car, then the connector on the fuel pump hanger, and then the fuel pump connector. After I rewire it there will be a fuse, relay connection, weatherpack connector, and then to the pump connector. My guess here is right now it is loosing over one volt based on all the connections and the length of the wire. The additional volt will basically net the flow rate about 35 lph at 45 psig.

Anyhow, I will update this as progress is made. Right now I have the tank out and the hanger stripped. Progress will depend on how busy the week is at work.
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Ill follow along your progress :nice:

I just upgraded my pump wiring last week (you replied to my post) I used the quantum fox body fuel pump wire upgrade harness which is 12g, but ran a 10g from my leash electronics 70a relay and used a non insulated butt connector with adhesive heat shrink. Now I'm considering using a weather pack or duetch connector after reading this.

That walbro connector you ordered only comes with 18-14g crimp connectors you'll need to order 10g.
This is definitely going to come out better than the video in the post. Too many colorful insulated junk butt connectors and electrical tape. Then the "quick disconnect" spade connectors at the gas tank instead of a proper connector like you're going to use. Had to cringe while watching that, the theory was there the execution not so much. I still have the 14g wire thats in the tank at the pump, maybe this thread will inspire me to fully complete eliminating the factory 14g feed wire. Good luck, keep us posted.
Hopefully it comes out like I want it to. I am fairly good at this stuff but there are others on here that do some really nice work. I am 100% sure that whatever I do it will be about 95% better than that video but again he is running three cars now with the way he did so it works its I just would not trust it.
Got the fuel pump strainer in and it was about 2/3 the size of the one I pulled out so that sucked. Searched a bit and found that the part number is a 125-157 for what I pulled out so I ordered two of those and they should be here early next week. Corrected the part number in the first post to keep the confustion down to a minimum.

Have some family stuff this weekend so won't get to work on the car anyhow. I am debating on having the tank cleaned which means I am going to have it done as there is some rouge in the bottom of it and that stuff will clog up a filter really quick.
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Parts are slowly coming in. Got the fuel pump connector and the terminals are 10-12 gauge so that was a relief. Company I bought the wire from contacted me and said they were out of the red but could offer orange so as hard as that was to find I agreed and it should be here early next week. Only think I lack to reinstall the hanger is the sock filter and that should be here early next week as well. I ended up ordering some weather pack terminal specific crimpers from Waytek so hopefully they will make crimping the terminals a lot easier than the crappy ones I had. Hopefully I can get to this in the next couple of weeks.
Okay, so I ordered a new fuel pump hanger with AN6 fittings and the return line upgraded to 5/16".

I am also going to rework the fuel lines from the tank to the fuel rails with AN6 line which I will cover here as well but this is the thread on the AN6 line, fittings, and fuel pump hanger:

Okay, so I ordered a new fuel pump hanger with AN6 fittings and the return line upgraded to 5/16".

I am also going to rework the fuel lines from the tank to the fuel rails with AN6 line which I will cover here as well but this is the thread on the AN6 line, fittings, and fuel pump hanger:

Hope that Quantum hanger works better than the one I had,never could get the feed to stop leaking.
High today was 46 degrees just like yesterday so I could not take not doing anything to the car and went out into the garage and made a little headway on the pump rewire portion of the project. Stripped the ground and hot wires for the pump out of the fuel tank harness and to do that I depinned the wires out of the connector. The old wire loom just crumbled in my gloves so that all went in the trash and I grabbed some new from my stash.

Wiring harness with the fuel pump wires depinned:

Wiring harness with the new loom, cleaned up connectors, and I even saved the original part number sticker:

Pulled the body harness back through the trunk floor, stripped the loom off of it and cleaned up the connector, and installed new loom on it as well.


All the other parts should be at the house when I get home after work tomorrow so hopefully I can make some headway in the evenings as the temperatures are supposed to start going back up. Need to get the fuel tank sealed up so I can wash it and get all the road grim infused dirt off of it. I removed the fuel level sending unit and took a look in the tank it is really clean so I am not going to mess with having it cleaned. The only place that had some rouge in it was the pump sump and I got that out with a rag and some carb cleaner. Once I get the wiring on the hanger done and the tank exterior cleaned up then I will start running the fuel lines.
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So Monkeybutt2000 and 2000xp8 pushed me over the edge on another thread and I canceled the order on the Quantum hanger and I ordered the Pro-M hanger this morning. They cautioned me on the Quantum unit so I started digging into it and there are a couple of threads over on the Corral that are not necessarily bashing the Quantum hangers but not speaking to highly of their support. The other part is that I am increasing the feed and return lines to 3/8" so having 5/16" lines on the hanger was chewing at me as well. Monkeybutt2000 had issues with a Quantum hanger in that he could not get the feed side to quit leaking and I do not want to deal with leaking hanger connections . I will never say that cost is not an issue but in this case I am definitely feeling you get what you pay for. Pro-M was twice the cost but I would rather have piece of mind so it is on its way to the house.

I added the hanger to the list in the first post and commented on changing directions on the stock fuel lines and hanger.
So parts poured in today all but the hanger and the 10 ga fuel pump wire. This is litterally about $175 worth of parts.


I had to try a fitting so I stopped by the big box chain lumber store and bought a 6" clamp to put the fittings together. Took the rubber feet off of it and then used a large diameter round rasp to notch the handle end for the fuel line.



From there it was getting the plastic fuel line in the brake line clamp and then putting that in the vise (tried holding all of this stuff and it was a pain in the ass), line up the 90 degree fitting (needed a really thin shim to keep it square) to the hose, and slowly squeeze the clamp handle.

Mock up of what it looked like but the brake line clamp was held by the bench vise:


Finished end:



So now that I figured out the hardest fitting to install this is definitely a green light.
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Not much progress this evening but I did relax the fuel line in hot water. Got the water up to about 200 deg F, submerged the fuel line that was in about 8” coils, let soak for about 2-3 minutes, removed and uncoiled it. It relaxed back to about 24” coils.


Should be able to get it to lay down from here with an old hair dryer.
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Fully committed as of 20 min ago. Factory fuel system is out from the rails to the tank. Appears the rear lines got a little hot at one point or several times.



Fuel lines were not impacted but the “protective” covering is no longer doing its job.
Haven't updated in a bit but the fuel pump hanger showed to have just delivered to the house so there will be some work in the garage this evening. I already have the fuel lines from the rails to just under the passenger door / floorboard area put in and was waiting for the hanger so I could figure out the line from the fuel pump hanger feed to the fuel filter inlet. I also got the fuel pump connector to the new 10 ga wires done. Used the weatherpack crimpers to do these terminals and it worked really well. Mixed up some epoxy last night and applied that to the bare wire portion of the terminal and around the area where the back of the terminal crimped into the PTFE jacket on the wire. This an effort to keep the fuel from migrating up the wire. I will do this on the weather pack connector as well for some insurance.