Modern Fuel Pump Module into an In-Bed Tank

[jamyers]

So my son's 1969 BubbaTruck has a combo in-the-bed fuel tank and toolbox, and ever since we converted from a carb to EFI we've had an in-tank fuel pump and a marine fuel gauge sending unit - which worked fine until the Carter pump started whining loudly after just 3 years. Plus the cobbled-together electrical pass-through to get power to the pump wasn't the best.

A year ago I picked up a GM fuel pump module off an Amazon overstock auction site for something like $40 (instead of the $250 retail).

After taking a good look at it, I realized that it actually specced for an 04-07 Hummer H2 - but it has the same required psi rating (58-60 at the engine), plus it has a filter and 70psi regulator along with a fuel sending unit that I could make work. AND it's got good GM Weatherpack electrical bits, so I can stop worrying about the fuel pump power shorting out to the tank.

Here's a photo of the module in question, a Delphi FG0393.

On the top (made of steel) is the fuel outlet (the smaller tube), a vent (bigger one), plus the 4-pin electrocal connector (2 for the pump and 2 for the sending unit) and a GM fuel tank pressure sensor (which I don't need so I removed it and plugged the hole with a bolt and oring.)

[notsolo]

..On mine The bigger line had several branches off to vent and canister....no return line....mine was from 2005, fuel cartridge looks the same. I modified both my trucks ( Boyd tanks in both) to use OEM fuel pump cartridges. If you have baffles in the tank the fuel gauge float may get hung up.

[jamyers]

out of the box, the module is intended to go into a fuel tank that's maybe 12 inched deep, and out tank is 24" deep- - so I disassembled the module top and bottom.

What's interesting is that the top and bottom can be clocked to each other in about 20 different ways, and I'll bet with different length rods connecting them. The whole thing is held together with plastic tabs.

Makes me think that if the one spec'ed for your modern vehicle was crazy expensive, you could look for one spec'ed for a different vehicle that was cheaper, and just reconfigure the thing.

Shown is the bottom of the top section, with all the different locating holes for the connecting rods. (I've removed the float/stopper for the EVAP system, and the Pressure Sensor).

Also looking at the insides of the bottom section, with the pump, filter, and regulator.

[jamyers]

I used some 1/4 x 20 threaded rod to connect the top and bottom, shifting the clocking around a tiny bit so the fuel sending float arm would clear the interior baffles - I had already cut a slice out of the center baffle for the previous sending unit to clear.

Put some jam nuts to keep pressure on the springs, which will keep the lower section pushed against the tank floor and in place.

Dorman 800-060 fuel repair kit comes with 18" lengths of nylon fuel tube and some barb connectors. Supposedly you can just push the nylon hose into the barbs (with either some grease or heat) and they'll stay put, but I opted to get a kit with a bunch of "single ear" crimp clamps (like PEX plumbing uses) to make sure the fuel lines are on tight. So one piece of 3/8 fuel line later and it's good to go.

Lengthening the wires was easy, with some heat shrink for added fun.

Used some heavy coat hanger wire that's the closest thickness I could find to replace and lengthen the fuel level float arm, had to tinker with bending it so that full was at the top and empty was just above the bottom.

The whole thing is right at 26 inches tall at rest, but the springs on the threaded rods let it compress down to the 24 inch tank height.

Boy do I wish I'd taken a picture of the complete setup before it went into the tank...

Previously we'd cut an access panel in the top of the tank, roughly 9" x 24". Using "The Right Stuff" gasket maker meant that I had to pry the access panel off and bent it up more than I liked, so I picked up a new 1'x2' piece of aluminum diamond plate from Lowes for (iirc) $35. Used "The Right Stuff" to glue the new piece back down (after cutting the holes in it, also emptying and cleaning the inside of the tank. Used a jig saw to cut the 5 inch round hole for the top section.

Installing the new taller module was the only tricky part, had to remove the fuel float arm, put the float into the tank, put the module bottom halfway in, connect the float arm to the sensor, then insert the rest of the module.

Then remove it all in backwards order because I forgot the cork gasket between the access panel and the top.

[jamyers]

Got a Dorman fuel line quick connector and used high pressure fuel hose to connect to the steel line feeding the engine, and a short piece of heater hose with a bolt clamped in the end of it to block the vent line (the tank has vented caps).

I could have hit the local wrecking yard for an electrical connector, but instead sprang for the $25 connector from Amazon.

Cut down and bent the old access panel piece to make a protective cover for the whole thing - keep the sun and monkeyfingers away from things.

And ta-DAH!! The finished product - a GM fuel pump that is SO much quieter than the old one ever was, along with a second filter, a better electrical pass through, and a neater install to boot.

[jamyers]

Originally Posted by notsolo

..On mine The bigger line had several branches off to vent and canister....no return line....mine was from 2005, fuel cartridge looks the same. I modified both my trucks ( Boyd tanks in both) to use OEM fuel pump cartridges. If you have baffles in the tank the fuel gauge float may get hung up.

Yup, apparently GM "got smart" and started putting the filter and pressure regulator inside the tank, so the regulator just dumps back into the tank and there's no extra return hoses.

The bigger outlet is vent, so yes no return lines (yay!)

From what I can tell, GM fuel injection all runs at roughly the same psi (60-70?), so my bet is that 99% of the fuel pumps, filters, regulators are the same, just the configuration changes.

Nice thing is that most aftermarket EFI's run the same pressures - our Holley Sniper runs at 60psi with its own regulator and return line, which I imagine are mostly redundant at this point. (btw, our fuel return is plumbed into the tank's threaded drain port, so any returning fuel goes straight to the bottom of the tank with no spraying.