The following information is for anyone with a 1989-1990 faulty fuel pump assembly (plastic unit that the pump and fuel gauge sender hangs off of).
My fuel pump unit had one of the plastic ports broken off where they exit the tank. Neither the aftermarket or the factory provides a new replacement fuel pump assembly or fuel tank for the 1989-1990 Dodge gassers. I did not like the idea of putting a junkyard unit in. Given the age of the plastic on used parts, I was afraid of a repeat problem.
So, I retrofitted a newer fuel pump (from the 1991-1993 Dodge rams with the gas engines) to my old tank which required cutting the opening larger and RTVing in the pump (not ideal though it shes holding fast).
To avoid bodging the pump unit in like I did, get a 1991-1993 tank from a newer ram. The filler neck and straps are the same from 1989-1993, so it should bolt in. I tried to locate one but could not find one in Montana in time.
Everything will bolt up nice and clean with the 1991-1993 tank, just make sure you get the same size tank (22gal vs 30gal) so you can use the same straps.
If you are going to do this, grab
-A 1991-1993 tank. Make sure you grab the electrical plug for the newer fuel pump.
-A new fuel pump unit from 91-93 Ram gasser.
-I also replaced all the rubber hoses (get 2 feet of 5/16” high pressure fuel hose, one foot of ¼” low pressure fuel, and a foot of 3/16” ), fuel filter, and the filler neck grommet (seal around filler neck as it enters the tank).
The install was fairly easy.
1) Remove the bed. Remove the 8, 9/16 bolts holding the bed down. Remove the filler neck, and unplug the electrical plugs at the rear. Pinch a nice fat power dip (I prefer Cope) and lift off the bed with a few buddies. Crack beers.
2)Remove the electrical connector, fuel lines (take a picture of these before you disconnect them so that you know what goes where).
Pro Tip: Some of these gas lines are stubborn; I find firing up a Pall Mall keeps my nerves calm and my hands steady. Just make sure you lean away and put on your safety-squints on when you pull the pressurized (output) fuel hose, it likes to spray fuel.
Once your lines are disconnected you can drop the tank.
3)Bolt in the newer tank. I’d make sure the tank is clean. The interior is black which makes it hard to see inside of; a lighter does the trick if you don’t have a flashlight handy.
Install the new fuel pump and connect the fuel lines. Both my new and old pumps were marked for the input and output lines. The 3rd line is for venting vapors to the charcoal canister (Thanks Obama).
I used fuel hose from the auto parts store with hose clamps. My factory hoses that clip into the fuel pump assembly fittings were shot. I cannot say whether the old factory fittings will connect to the newer style fuel pump (if someone can verify yes or no, let me know).
4) Solder the newer plug onto your truck. If you want to break down and risk getting towed by a Ford, use crimp connectors.
This is as easy as wiring gets.
-The green/black wire is the hot for the pump. The colors are the same for both new and old plugs.
-The blue/yellow wire is for your fuel gauge. The colors are again the same for new and old plugs.
-The last 2 wires are for ground. On my truck the old plug had white ground wires. The new plug had black ground wires. Don't worry about swapping them, they join a couple inches up the harness on the truck.
-The center prong on the fuel pump is not connected to anything and is not needed. To be crystal clear, even though there are 5 prongs on the fuel pump only the 4 above connections are necessary. The center prong is not connected to anything.
Make sure you fire up the truck before you put the bed on to make sure everything works well. My truck is running better than ever with the new pump (was hard starting and stalled while rolling up to stops). Now she fires up instantly and no stalling. My fuel gauge works great too.
Notes on my photos: Take note of hose routing. I also needed to plug a hole in the top of the new pump (ace hardware had a brass fitting that fit tightly. I drilled and tapped if for a barb fitting to install the vent tube to. I RTV'd it for good measure (Permatex Gray).
The 2nd photo compares the wiring from the old round plug to the newer flat plug. Before installing I checked the resistance of the fuel gauge sender, it was basically the same. Everything works great.
