JGC403
Well-Known Member
Figured there might be some interest in this since there are more of these Self Learning Fuel Injection Systems coming on the market. My truck is a 1985 D-150, Its got a mild build 383 in it, Mopar Performance Solid Lifter Cam, 906 heads ported with Mopar templates, 9.8:1 compression ratio, Eddy Performer RPM intake manifold, and Quick Fuel Technology's Fuel Injection System. I'm having issues with the QFI system right now, doesn't seem to be self learning like its supposed to. If I was going to get one again I would get FITech system. I haven't heard anything but good news about that system.
Onto the In-tank pump. All of these fuel injection systems require a high pressure electric fuel pump. I got the QFT kit that came with a 255LPH external pump. The pump couldn't pull the fuel out of the top of the tank. For these pumps its best to have the fuel gravity feed to the pick up, since they don't suck as well as they push. Since its a plastic tank you can't cut and weld a sump in the bottom of the tank for the pick up. So it took some time but I finally tracked down a fuel tank from a 1991 D-150. The 1991-1993 trucks use a in-tank fuel pump. The stock pumps are only about 121LPH and can only support about 300hp.
So I wanted to put a 255LPH pump in the 1991-1993 tank. There are no bolt in sending units with the 255LPH pump for the 1991-1993 Trucks.
So the following is how I modified a stock sending unit for the universal Walbro 255LPH pump.
IMPORTANT: If you are going to retrofit a pre-1991 truck to fuel injection, you need to find a fuel tank and a stock sending unit with a return line. The replacement Dorman sending unit will not work, its all glued together and doesn't come apart like the stock sending unit does.
You will also need:
-1991-1993 Fuel Tank
-1991-1993 return style sending unit
-pigtail from donor truck that plugs into sending unit
-Walbro fuel Pump part #: GSS340
Walbro GSS340 Fuel Pump - 255LPH High Pressure Fuel Pump
-Replacment Fuel Pump kit would make it a little easier but you will get an extra pump that you don't need, part #: GCA749
Dodge D100 - 150 - D200 - 250 - D300 - 350 - 1993-91 6 Cyl. 3.9L Walbro OEM Fuel Pump Kit - PN# GCA749
-Or Gates In-tank fuel line part#: 27093
Amazon product ASIN B001R5XSGU-hose clamps
Amazon product ASIN B0040CU0HM-Fuel Rail fitting 3/8"
Tanks Inc. Fuel Rail Fitting Adapters 640853
-Fuel Rail fitting 5/16"
Tanks Inc. Fuel Rail Fitting Adapters 640863
*If you buy the Walbro replacement fuel pump kit you don't need to get the Gates submersible fuel hose. The kit comes with fuel line. But you should replace all of the filters on the sending unit, the big bottom one and the one that is inside the sending unit.
I got the fuel tank with sending unit from the junkyard. When I got it home I started with removing the sending unit from the tank then disassembling the sending unit to take out the old pump. I had to cut the hose clamps off of the plastic line coming out of the pump. I tried saving the line, heated it a little but i still messed it up, never had luck with those hard plastic fuel lines. So I cut the fitting off of the other end of the hard plastic line, the fitting will be re-used. Took the rubber bushing off the bottom and the rubber isolator off of the old pump and put it on the new pump. New ones come in the Walbro kit so you don't have to do this.
I removed the pump and here you can see the difference between the height of the stock pump and the Walbro 255LPH. The Walbro is shorter. You can see that the pickup side of the pump, both are in the center and the same size. The pickup on the walbro is a little shorter but it doesn't matter.
I re-assembled the parts that go inside the lower half of the sending unit, set the pump in and put the blue cage on top of the fuel pump. I was able to figure out where to re-drill the holes for the screws that hold the blue cage in place. The blue cage should press down a little on the pump to hold it in place. In the picture below you can see I have one screw in place and I'm drilling the hole for the 2nd screw on that side. A couple of inches above you can see the original holes for the screws that held the cage in place for the taller stock pump.
Here you can see inside the sending unit with the fuel pump mounted. You can see the 4 screws that hold the blue cage in place.
So I took the pump back out and put the Gates submersible fuel line on the nipple coming off the pump and clamped it on with one of the hose clamps. The hose came 12" long and I just left it like that for now I'll trim it later. I then reassembled the lower half of the sending unit put the filter back on the bottom of the unit then the pump and the blue cage last.
Next I measured the depth of my tank. I will be able to determine how much I need to trim off the Gates hose.
I then trimmed a couple inches off of the Gates hose put the fitting (that I had removed off of the hard plastic line earlier) on and plugged it into the underside of the top of the sending unit. Here you can see the fitting plugged into the underside of the top of the sending unit.
I then assembled the rest of the sending unit. With it on a flat surface measure to the lip that seats onto the gas tank. It was a lot taller than the measurement that I took of the fuel tank. So I took it apart and took a little more off of the hose. I then put it all back together again. It was a little taller still but you want it a little taller so its pressed up against the bottom of the tank. I compressed it until the measurement was the same. I checked to make sure the hose didn't kink. The hose was OK.
So last thing I had to do was change the electrical connector for the pump, inside the sending unit. I soldered the old wires to the wires coming off of the new plug but you can probably use crimp connectors just make sure that the crimp connectors on the positive and the one on the negative will never touch. When I spliced the new plug into the wires I cut the ground and positive wire un-even. I used shrink tubing on my soldered joints, but if for some reason the gas would dissolve the shrink tubing where the soldered joint is the ground and positive wires will never touch one-another because I cut them un-even. If you look close you can see the shrink tubing on the red wire then a couple inches down you can see the shrink tubing that I have on the black wire.
Next you will have to splice the plug that plugs into the sending unit into your trucks wiring harness. There are 3 wires coming off of this plug one is a ground one is for the fuel gauge and the other is power for the pump. The wires that go to the factory tank on pre-1991 trucks will be for the ground and for the fuel gauge. The power wire for the pump you will need to run back from whatever aftermarket fuel injection system you decide to use.
Last I used braided nylon fuel lines, that is was came in the QFT fuel injection kit. I found that the fuel rail adapter fittings snap right onto the feed line and return line coming off of the sending unit. The 3/8" one is for the feed line (blue one in pic) and the 5/16" one is for the return. Those will connect to the -AN hose ends.
I then put it all back together and have a sending unit that will support 500+ horsepower.
Onto the In-tank pump. All of these fuel injection systems require a high pressure electric fuel pump. I got the QFT kit that came with a 255LPH external pump. The pump couldn't pull the fuel out of the top of the tank. For these pumps its best to have the fuel gravity feed to the pick up, since they don't suck as well as they push. Since its a plastic tank you can't cut and weld a sump in the bottom of the tank for the pick up. So it took some time but I finally tracked down a fuel tank from a 1991 D-150. The 1991-1993 trucks use a in-tank fuel pump. The stock pumps are only about 121LPH and can only support about 300hp.
So I wanted to put a 255LPH pump in the 1991-1993 tank. There are no bolt in sending units with the 255LPH pump for the 1991-1993 Trucks.
So the following is how I modified a stock sending unit for the universal Walbro 255LPH pump.
IMPORTANT: If you are going to retrofit a pre-1991 truck to fuel injection, you need to find a fuel tank and a stock sending unit with a return line. The replacement Dorman sending unit will not work, its all glued together and doesn't come apart like the stock sending unit does.
You will also need:
-1991-1993 Fuel Tank
-1991-1993 return style sending unit
-pigtail from donor truck that plugs into sending unit
-Walbro fuel Pump part #: GSS340
Walbro GSS340 Fuel Pump - 255LPH High Pressure Fuel Pump
-Replacment Fuel Pump kit would make it a little easier but you will get an extra pump that you don't need, part #: GCA749
Dodge D100 - 150 - D200 - 250 - D300 - 350 - 1993-91 6 Cyl. 3.9L Walbro OEM Fuel Pump Kit - PN# GCA749
-Or Gates In-tank fuel line part#: 27093
Amazon product ASIN B001R5XSGU-hose clamps
Amazon product ASIN B0040CU0HM-Fuel Rail fitting 3/8"
Tanks Inc. Fuel Rail Fitting Adapters 640853
-Fuel Rail fitting 5/16"
Tanks Inc. Fuel Rail Fitting Adapters 640863
*If you buy the Walbro replacement fuel pump kit you don't need to get the Gates submersible fuel hose. The kit comes with fuel line. But you should replace all of the filters on the sending unit, the big bottom one and the one that is inside the sending unit.
I got the fuel tank with sending unit from the junkyard. When I got it home I started with removing the sending unit from the tank then disassembling the sending unit to take out the old pump. I had to cut the hose clamps off of the plastic line coming out of the pump. I tried saving the line, heated it a little but i still messed it up, never had luck with those hard plastic fuel lines. So I cut the fitting off of the other end of the hard plastic line, the fitting will be re-used. Took the rubber bushing off the bottom and the rubber isolator off of the old pump and put it on the new pump. New ones come in the Walbro kit so you don't have to do this.
I removed the pump and here you can see the difference between the height of the stock pump and the Walbro 255LPH. The Walbro is shorter. You can see that the pickup side of the pump, both are in the center and the same size. The pickup on the walbro is a little shorter but it doesn't matter.
I re-assembled the parts that go inside the lower half of the sending unit, set the pump in and put the blue cage on top of the fuel pump. I was able to figure out where to re-drill the holes for the screws that hold the blue cage in place. The blue cage should press down a little on the pump to hold it in place. In the picture below you can see I have one screw in place and I'm drilling the hole for the 2nd screw on that side. A couple of inches above you can see the original holes for the screws that held the cage in place for the taller stock pump.
Here you can see inside the sending unit with the fuel pump mounted. You can see the 4 screws that hold the blue cage in place.
So I took the pump back out and put the Gates submersible fuel line on the nipple coming off the pump and clamped it on with one of the hose clamps. The hose came 12" long and I just left it like that for now I'll trim it later. I then reassembled the lower half of the sending unit put the filter back on the bottom of the unit then the pump and the blue cage last.
Next I measured the depth of my tank. I will be able to determine how much I need to trim off the Gates hose.
I then trimmed a couple inches off of the Gates hose put the fitting (that I had removed off of the hard plastic line earlier) on and plugged it into the underside of the top of the sending unit. Here you can see the fitting plugged into the underside of the top of the sending unit.
I then assembled the rest of the sending unit. With it on a flat surface measure to the lip that seats onto the gas tank. It was a lot taller than the measurement that I took of the fuel tank. So I took it apart and took a little more off of the hose. I then put it all back together again. It was a little taller still but you want it a little taller so its pressed up against the bottom of the tank. I compressed it until the measurement was the same. I checked to make sure the hose didn't kink. The hose was OK.
So last thing I had to do was change the electrical connector for the pump, inside the sending unit. I soldered the old wires to the wires coming off of the new plug but you can probably use crimp connectors just make sure that the crimp connectors on the positive and the one on the negative will never touch. When I spliced the new plug into the wires I cut the ground and positive wire un-even. I used shrink tubing on my soldered joints, but if for some reason the gas would dissolve the shrink tubing where the soldered joint is the ground and positive wires will never touch one-another because I cut them un-even. If you look close you can see the shrink tubing on the red wire then a couple inches down you can see the shrink tubing that I have on the black wire.
Next you will have to splice the plug that plugs into the sending unit into your trucks wiring harness. There are 3 wires coming off of this plug one is a ground one is for the fuel gauge and the other is power for the pump. The wires that go to the factory tank on pre-1991 trucks will be for the ground and for the fuel gauge. The power wire for the pump you will need to run back from whatever aftermarket fuel injection system you decide to use.
Last I used braided nylon fuel lines, that is was came in the QFT fuel injection kit. I found that the fuel rail adapter fittings snap right onto the feed line and return line coming off of the sending unit. The 3/8" one is for the feed line (blue one in pic) and the 5/16" one is for the return. Those will connect to the -AN hose ends.
I then put it all back together and have a sending unit that will support 500+ horsepower.
Last edited:
