I have a '69 Special w/ 455. I have converted to FI, and would like to use an in-tank pump. Can I just use a GN setup complete with sending unit & fuel pump, and drop it into my tank? Will it fit, or am I gonna have to make a custom unit? Thanks! -Bob Cunningham bobc@gnttype.org
Nope Hey Bob, I've had both my GN and GS tanks down and sorry to say, but I'm pretty sure the GN unit has a bigger opening to accomodate the fuel pump. I'm not sure the factory GN fuel pump could feed your 455 either.
The factory GN pump couldn't feed a horse!ou: You might try switching out fuel tanks and then get a good pump from Red Armstrong!
Thanks! I wasn't gonna use the stock pump, it's more the pickup arrangement that I'm concerned about. I found a place (Rock Valley) that will take my tank and convert it for FI (pickup, sump, etc.), so I'm gonna go that route. The pickup on the GN is totally different than the GS, so that ain't gonna fly... Thanks! -Bob Cunningham
Bob, the GN pump(I actually have the HP Walbro replacement) can fit in the stock tank, I have one in my 64. However, it's a precarious fit, and you have to trust the fuel hose to hold the pump in place. After some teething problems, mine has been working great. I ran a new 3/8 line and use the 5/16 for the return. The pump works all the way till the gauge gets to "E" just like with the stock arrangement. If you get yours converted, be sure and post some pictures. I think the in-tank is the best way to go for reliability, appearance, and performance. External pumps are a PITA. :af:
And? Adam, can you elaborate on your in-tank pump set-up? I have been searching for info on an in-tank fuel pump for my 71 GS 455. Bob is using a high pressure fuel injection set-up,so that won't work for my carb. What Walbro pump did you find that had the proper pressure and volume for a healthy Stg. 1? How did you regulate it? o No:
Al, I used the same pump as the GN, 255lph unit marketed for GN's and 5.0 Mustangs. They are all the same Walbro pump once the package is opened. I got mine from a Mustang guy for $100. Just because a pump is capable of pumping high-pressure doesn't mean it won't work on low pressure. It just doesn't pump at peak efficiency at the lower pressure. You can see the pressure Vs flow curves for the pumps on GNT-type.org. However, anybody that thinks that you'll have fuel delivery problems with this pump because of too many G's on acceleration is very wrong. It delivers enough fuel for some GN's to run in the 10's with a 50 PSI line-pressure. It delivers a little more fuel at the lower line pressures we use. Ideally, I'd like a pump designed to deliver more volume and dead-head at about 15-20 PSI to overcome any g-forces of acceleration, but this one works and is cheap enough. I cut the sending unit's pickup tube off so that the inlet of the pump would sit about where the pickup tube used to start. Using a flaring tool I then put a bulge in the tube to help keep the hose on. I drilled the old 1/4 return-line in the sending unit and replaced it with a 3/8 tube I soldered in its place. The outlet of the pump is a slippery and small plastic deal. I took another scrap of tube, put a bulge in it, and drill a couple of small holes in it . I then heated it and slipped it over the plastic outlet of the pump which extruded the melted plastic through the holes and into the tubing. Have some cooling water handy as I almost ruined my new pump when it stayed melted longer than I thought it would. I took the sender from a tbi equipped car and removed the fuel pump wire assembly to retrofit it into my sending unit. Here's the hard part. You have to put the pump in the tank first, suspended by the plug. then put the float for the fuel gauge in, and lastly, hook up the fuel line. Of course its a bugger, but I've done it several times before getting everything right, and it can be done (lots of swearing). Don't use the crappy line you get with the fuel pump, and of course use fuel injection hose. If I did it all over, I would use 3/8" for both feed and return lines. I have a Mallory return style fuel pressure regulator that (just last week) replaced the Holley unit I started with. I think because the 5/16 return line I can't get fuel pressure below 7-8 PSI. My 64 has the sending unit install in the front of the tank, but I'm pretty sure you can adapt what I did to your newer top-loading tanks. I am thinking of trying to make a patch-panel to weld in a sending unit from something newer that is more installation friendly. A bracket may also be possible from the return line to help hold the pump. Getting it all through that little hole is the tough part. Ask any industrial pump guy, a submersible pump is the only way to go for efficiency. Let me know if this doesn't cover anything well enough. I shoulda took pictures but didn't.
Excellent Thanks Adam, I had no idea I could use a high pressure pump and regulate it down. With the info you've supplied I should be able to come up with a set-up. I wonder how close a GN tank is to a 71 GS tank..........That would solve a host of problems..... Adam, did you switch to a Mallory regulator simply because it's a return style or was there a problem with the Holley?
The GN tank is not centered- the GN has a spare tire well in the trunk. The fuel pump opening on the GN is about 5", vs. 2-1/2" on the GS tanks. If you try to go like Adam, I would consider trying to add some internal baffling, and keeping at least 1/4 - 1/2 tank of gas in the tank at all times. -Bob Cunningham
I have a fuel pressure gauge,and only when the gas tank is close to empty have I seen any pressure fluctuations. I am sure that baffling would be a nice thing to add though. I went to the Mallory because it is a true bypass regulator. The holley I had set up so that it bled fuel back through the return line, but it couldn't handle the pressure the pump was able to build when it was trying to limit pressure to the carb. Basically the Holley setup I was using was half-a**ed. It got me by, but I knew it needed changed to be right.
