DigiFant, Single Fuel Pump Conversion

Start with Brian's in-tank pump replacement write up to get you into the tank and the old in-tank pump removed.

I removed both the in tank pump and external pump from my '92 Cabby, replaced both with a Chevy in tank pump and a Dodge Truck fuel filter mounted under the hood.
ALL the external stuff around the main pump is gone, including the accumulator.

Since there are no baffles inside the tank and there is no longer an accumulator to keep supply to the main pump inlet, it will starve while hard cornering and below 1/4 tank. I may retrofit a CIS accumulator to address the starvation issue. (This also told me the stock in tank pump must also starve during hard cornering with low fuel, since the accumulator keeps fuel available to the main pump inlet, the driver never notices.)
The starvation is self correcting, the cornering speed simply drops until fuel gets back to the pump. I don't corner hard often enough to care. I used to.

As currently installed, the pump is considerably noisier than the factory set up, eventually I'll pull it back out and fine tune the fit up.
I did pull it back out and installed the Aitex supplied rubber noise damper sleeve, see the last pic. I also put the origial VW pick up screen on, it fit perfectly. The Chevy screen was a bit of a beach to wrangle in there.

The Chevy pump has a built in check valve, no worries on that score. It put out a quart in about 22 seconds, factory pump takes about 30 seconds. Pressure is regulated by the fuel pressure regulator, I didn't bother checking.
 
I did have to crimp one connector, solder one other. I had to shorten the pipe on the fuel level sender to get it to fit, the Chevy pump is a little longer. Shortening included removing the hose barb, or flared end, the Chevy pump had no barb either, I figured it wasn't really needed, there's no place or room for the pump to blow itself off of the fitting.
 
The pump I used was an Airtex E3240, I used a WIX 33321 fuel filter.

The Chevy pump comes with a connector kit of a sort, there's plenty to work with. The Chevy GROUND IS BLACK!!! Totally Bassackwards from what we are used to with VWs where black is power, brown is ground.
 
Before you yank the hoses, stuff a 'leader' wire well inside each, I used 12 gauge. Pull the hoses with wires out through the bottom, remove the accumulator with the hoses as a unit. Follow the new hoses up the leader wires. It was pretty easy reaching top and bottom sides at the same time by myself with just one jack stand under the right rear of the car.
 
There is one spring clip on the leading edge of the tank you'll have to deal with, it holds a hose. I pried, levered and pulled on it until it was finally mutilated enough to remove it, I left it out and still sleep easy. It was holding either 6 or 7 in the layout pic below, the clip itself is similar to 34 in the vent hoses pic..
 
I initially used the stock fuel filter, didn't even have one to change. I had planned on an underhood mounted filter, so I left enough hose between the sender and the stock filter inlet that I could re-route from the sender directly to the main feed line once the stock filter was removed.

It's been in the car for at over a year, probably 15,000 miles or more, no other issues besides what's already been mentioned.
 
Shop that Airtex pump part number, compare to the the cost of replacing both stock DigiFant pumps, you'll know why I went this route. I think the WIX filter I used is considerably less than OEM too.
 
Anyway, approximately a quart in 30 seconds is the stock in-tank pump's specs, what it is expected to pump. If a stock pump can't pump that quart, it's due for a dirt nap.

You know that while plastic accumulator/reservoir in-line between the in-tank and main pumps? All the in-tank pump has to do is keep that accumulator/reservoir full so that the main pump can draw from that accumulator/reservoir.
That accumulator/reservoir has four hoses, the output of the in-tank pump, the inlet for the main pump, return flow from the fuel loop/pressure regulator and return flow into the tank. There are no valves or anything else inside except for a slight restriction in the return line to the tank.

The in-tank pump pumps rather freely with little restriction into the accumulator/reservoir, excess in-tank pump flow goes to the back tank, in-tank pump pressure build up is avoided (or relieved) via the return line to the tank.

Stock, all the in-tank pump and the accumulator/reservoir do is to keep fuel available to the main pump especially during hard cornering with less than 1/4 tank when the in-tank pump starves, there being no baffles inside an A1 (or I think A2) tank.
 
 
2 pics of old and new pumps side by side...........


How much to cut off from the pipe on the level sender:
Cut it short enough that when assembled, there's no pump to pipe contact at the top, nor pump to tank contact at the bottom.


As assembled and installed the first time, make sure those hose clamps are TIGHT, there are no barbs on the fittings.


Soldered wire connection at the sender plate, old and new.......


The factory hose layout.


The vent hose layout....


Components removed and discarded.


WIX, Dodge Truck fuel filter. I bolted it's mounting tab to a stud on the right (passenger side) front strut tower where an Air Conditioning line used to bolt on.
I found a wide variety of fuel filters and mounts available. Hound your Parts Store Counterman/woman to let you browse the WIX catalog. You want 5/16" fittings in and out and a mounting configuration to suit your application and taste.


Slightly tweaked assembly, 2nd time, 4 months later.

There is absolutely no way I'd expect this swap to work on a CIS car. If such a pump was capable of adequate pressures for CIS, I'd expect immediate failure of the hose clamps holding the pump to the lever sender plate pipe, there are no barbs there.

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