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Converting to electric fuel pump on frame

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by CMDR BOB, Jul 11, 2014.

  1. CMDR BOB

    CMDR BOB New Member

    Have a 1998 k2500 slt suburban 7.4---has anybody converted to a frame mounted fuel pump ?????
     
  2. Crawdaddy

    Crawdaddy ↑↑↑ Has no life Staff Member 5+ Years 1000 Posts Platinum Contributor

    I haven't heard of this yet, but I think the tank for the 90s Suburban is very similar if not the same to the 80s bodystyle tank. You may want to check to see if a carbeurated fuel pickup from an 80s Suburban would work. I suspect it would and would allow you to pull out of the tank and keep an operating fuel level sender.

    Why are you wanting to switch to a frame-mounted pump?
     
  3. poncho62

    poncho62 Member 1 Year 100 Posts

    If you have to go into the tank to change the sender, might as well put the proper pump in.....Why are you wanting to do this, to go with a carb?

    I dont think a an external pump is going to give the pressure needed to run EFI
     
  4. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    FWIW, I remember my old Ford BII had this kind of set up (system was designed to run at 40 psi). I thought it worked just fine. Ford's system actually used 2 pumps -- a low pressure pump inside the tank which fed a high pressure pump on the frame. In some ways, I think this was its main weakness -- two pumps, and the system would fail if either pump failed. It doesn't seem like it was any worse than the problems we seem to have with GM pumps. The key will be getting a pump rated for high enough volumes at high enough pressures. Let us know if you decide to pursue this.
     
  5. Raredirt

    Raredirt New Member

    Yes I have. That is, I have installed an external pump in place of the in-tank pump. I can look up the particulars, but I know it was a Carter pump. I also included a large spin-on filter, eliminating the screens on the pickup in the tank. IMG_4232r.jpg

    I felt that $6-700 for a fuel pump replacement was outrageous and resolved to make service easier. I also cut a hole in the floor over the pump so dropping the tank (and a 44 gal tank can be pretty heavy) was no longer necessary. I gutted the pump/sending unit assy so that all that remains in the tank is a tube pickup with the pump housing (to provide a sump) and the sender.
    P1020395r.jpg P1020398r.jpg

    The result is a bit noisier, but once underway, you don't notice it. Some folks will tell you that the pump must be submerged to cool properly, but the volume of fuel it pumps is more than adequate to cool it. I verified this by hooking up a gallon jug to the inlet hose to make sure everything was well primed, and at idle, it sucked down the gallon in nothing flat. Evidently the bypass valve allows nearly full volume to be pumped at all times.

    I'd be glad to share more photos and text off list with anyone who is interested.
     
  6. jmcover

    jmcover Rockstar

    I'm In! Is that a Burb? Did you keep your measurements for the cut out?
     
  7. Raredirt

    Raredirt New Member

    It's a '99 Suburban 1/2 ton. I did not record any measurements, but you can see where the tank top components are by looking through the wheel well over the frame rail. You can see all the way through the vehicle there and gage where you need to cut. Cutting is tricky as you can imagine. You don't want to cut a fuel, vent or return line. I used an assortment of tools. Rotary cutoff wheel, sabre saw, snips and maybe a hacksaw. There is a transverse stiffener just over the fuel pump opening. Cutting that will weaken the floor, but I don't (didn't that is, the rig got wrecked) put heavy dense loads in it.

    If I were to do it again, I'd move the opening about 2" further aft.

    That's food for thought. Any more details we can cover off list if you want to proceed.

    I originally cut the opening just so that it would be easier to service the standard pump. Only later did I decide to replace the in-tank pump with an external one.
     
  8. jmcover

    jmcover Rockstar

    Thanks and sorry to hear about your rig!

    My pump is still healthy now, but when the time comes...
     

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