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Replacing entire fuel system

M.H. Yount

Active member
Joined
Nov 1, 2008
Location
Charlotte, NC
Decided it was time for a change. I'll be putting a Deatschwerks 300 L/Hr in-tank pump in the car and completely re-plumbing the system. The Ford engine has supply/return connections on the front/passenger side of the compartment. So I'm doing away entirely with the Volvo fuel pumps/lines/filter (firewall) -- and replacing it with a system that runs up the passenger side of the car. It'll start with the fabrication of a new tank-top using .0625" aluminum plate. -6AN bulkhead fittings will attach to that -- and from there I'll run Push-Tite series 8000 textile-braided hose to the front for supply and return. I'll mount a Russell 10 micron Profilter up front some place I can easily access to change the paper element. Not in a big hurry - so this one will take a week or two (or three -- I just retired and seem to not be in a hurry for anything). This set up should handle the LS3 I ultimately want to put in the car, and also make room for a pair of mufflers on either side of the car ahead of the rear axle.

Starts by rough cutting the aluminum plate to a 90mm size (a bit more than 3.5"). I'll trim it for a perfect fit once I've removed the existing in-tank pump assembly and can measure more carefully. I went to the Pull-A-Part to see if I could modify a factory tank-top --- but once I saw how the compression ring holds it in -- it was easier to simply cut a piece of aluminum.


 
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My fittings arrive today and tomorrow (3-16/17) so I should be able to remove the factory in-tank tomorrow. I want to pull it out and take some careful measurements/references before I start drilling holes in the aluminum. I'll be creating a brand new circuit to fire the pump. The Ford ECU has a circuit that provides ground specifically for a fuel pump -- 3 seconds of prime at ignition on unless it sees an alternator field (engine running). Hot out of a new 16A fuse in the fuel pump spot on the box, and a new 10 gauge wire to the back --- all out of a new and more robust relay. Do away with the factory set up altogether.
 
About 90% of what I ordered arrived today....enough to begin taking the existing system off the car this weekend.

 
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Most of the rest of the fittings arrived today. So -- no reason to put things off any longer. Safety first -- started with flipping the disconnect on the battery. Also realized I'd have some gasoline fumes in the car/garage - so went ahead and turned on all lights, box fan on low and opened window/attic stairs. Wanted to minimize any ignition sources -- so turn everything on first and leave it on.

Started here --



Popped the plastic carpet pins and get it out of the way --



Remove the plastic cover to get to the electrical connections, and remove the access plate --



Doesn't look bad at all given the corrosion I've seen on some of these cars! Cleaned up with a wire brush and a dental pick, shop vac'd all debris up, worked a rag under the supply/return hoses to catch any fuel that might be there when I cut the hoses -- and marked the vent and return lines for a reference when I put things back together (want to be sure the gauge sender is facing the right way.



Cut both hoses (virtually no fuel came out) and put IPD's fancy lock ring tool on and give it a 1/8th turn counter-clockwise.....



....and without too much fuss, out it comes! The whole thing took about 10 minutes. It's an AC pre-pump and the connecting hose looks new so I'm thinking it's been replace at some point. But not since '96.



Then I took my new tank-top (see first pics) and with the old o-ring and retainer I sealed the tank to stop fumes from filling the garage and to keep stuff from finding its way into the tank.



I'll take some careful measurements on bottom of pump and sender location and then decided if I want to modify the factory assembly or make a new assembly using the aluminum plate.
 
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After examining the stock assembly more closely I think I'm going to take a stab at modifying it to accept the new fittings. I believe I can install the new bulkhead fittings in the two holes where the sender wire and the pump hot wire exit the top. I'll use the existing vent line (cut off the bend) as an exit point for the wires. This will allow the sender to stay in place attached to the stock return line - which I'll have to seal at the top. The pump can be bolted to the bottom of that same line in stock fashion. I can cut off and seal the stock supply line. The unit will be grounded in the same way it currently is. We'll see what havoc I can wreak with the cut-off wheel and the Dremel in the morning.
 
Partial disassembly of the sender/pump 'assembly'. Removed the pre-pump. I can modify the bracket to accept the Deatschwerks unit. I was able to pry the electrical connections out of the housing. I'll make a new soldered connection to connect the fuel gauge sender to the harness. I simply cut the pump hot wire as new connections will be made for the new pump. There have been issues with bad grounds causing pump challenges/failures -- so I'll run the hot and ground wires out of the tank to be sure I've got a good ground outside the unit. I'll cut the stock supply line off much shorter and use it as a conduit to run my electrical wires out of -- hot, ground and sender. I'll leave the capped vent line as it is and I'll cap the stock return line. In the bottom picture you can see the holes where the electrical connections came through. I'll modify those to accept the -6AN bulkhead fittings for supply and return lines. Time for the baby cutoff wheel...



 
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Opened up the backside so I have access to the bulkhead fitting washers and nuts; cut off the stock supply line so I can use it as electrical conduit; opened up the existing electrical connection holes for the bulkhead fittings.



Also cleaned up the top -- cutting off stock supply/return ells so I can cap the return line. Have one of the bulkhead fittings test fit in the hole.



After I finish up the openings, it looks like if I open up the raised edges ('nubs') of the plastic pump clamp, the pump will go in the stock holder just fine. I'll put a stainless clamp around the pump to create a barrier that keeps the pump from trying to sit/fall any lower. Of course, the hose to the supply line will help hold it in place as well.
 
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Bulkhead fittings installed and the pump test fit. Thought I could open up the plastic clamp enough to fit the DW pump - but was concerned it was too snug and might suffer a stress related failure over time. So ended up making a small 'slit' in the plastic clamp and putting a stainless clamp around it all. Looks like it's going to work fine.





 
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Picked up my $5 40A automotive relay at Radio Shack. And I bit the bullet and bought the SAE30R10 submersible hose for the pump to 3/8" supply line inside the tank. That is one pricey little piece of 1' hose. Also got the SAE30R9 hose rated for EFI systems to make the short connections to the fuel rail barbs up front. This evening I'll try my hand at flaring and bending a small piece of 3/8" aluminum tubing to go between the bulkhead fitting and the pump outlet inside the tank. The piece will only be 4"-5" long -- but it requires some interesting bends in order to keep it as close to the stock return line is possible. I've got to keep everything compact so I can have a hope of getting this beast back through the stock tank opening. I'm also going to take a careful measurement to the bottom of the tank so I can adjust the pump pickup height, the return tube height and the sender float. My gauge reads so it leaves a good 3-4 gallons in the tank when it's showing empty. I can see now how to adjust/fix all that.
 
Thumbs up!

I like....
Kinda backward from most, trying to get rid of intank pump..but would negate vapor lock effect when intank removed and just use under car pump..smart.

Congrats on finding a boat load of time on your hands...looks like it's off to a good start..enjoy..you earned it.
 
In-tank is a better mousetrap -- quieter, cooler, never loses prime. There is little downside especially since Volvo saw fit to make it relatively accessible. I'd prefer a LITTLE bigger opening to work with -- but at least this small opening into the tank makes you think about how you route/package things in this pump/sender assembly. The irony is that I'm doing it mainly so I have more exhaust system options....my wife is going to kill me.

I guess I equate vapor lock with low pressure (carbs) and high under-hood temps. While technically a loss of prime is vapor lock, I don't think the term was coined to describe what happens when you can't overcome a gravity issue to get fuel to the suction side of the inline.
 
Very nice and informative. I've had a DW300 pump sitting around the garage for several months now, I need to get around to putting it in.
 
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