Fuel High Pressure Fuel Pump Went Silent...

Discussion in 'Fox 5.0 Mustang Tech' started by stang89bidges, Apr 11, 2014.

  1. Oh boy. So I have a high pressure fuel pump for my Vortec SC. This thing from day 1 has always been super loud. Every time you get in car, turn the key to let it prime before starting the engine it screams under the car for 2 seconds.

    Well, about 3 days ago it stopped screaming/whining loudly and now it sounds more muffled. What do you think is up? I believe it's still working as the car doesn't run any different.
  2. I had a similar (if not the same) pump & it sure was loud. Wrapped some foam around it to make it a bit quieter. Removed it when I had to replace the in-tank pump.

    If it suddenly went muffled, something is up. Is your fuel filter between the in-tank & the boost pump?
  3. I will get under the car tomorrow and do some troubleshooting I guess. I will probably just go ahead and replace the filter while I'm under there, might be a good idea. Hell, maybe I will take off the rear diff plate and change the lube too.. o_O
  4. So I got under the car. I will include a few pics. It appears the new fuel pump is before the fuel filter. So the high pressure fuel pump has to pump through the filter before it gets to the engine.

    Here are pics. They aren't great, not much room, when I finish my water pump I will be able to jack it up and get a better look.




  5. Looks like a nice pump. Vortech T-REX 50/70. I guess that makes sense with my vortech SC ;)
  6. That is how I am setup. I will change the fuel filter and hope for the best first time I turn the key on afterwards.
  7. So I got my car back together finally. Got all my mods done(that I could afford). Had a friend turn the key for me before I started her up and yep, the inline vortech fuel pump has gone out. I put a meter on her pos terminal and ground to chassis and she is getting elecricity.

    So. How bad would it be to drive this thing without the high pressure until new one came in? I'm running the vortech V2 with FMU. Stock In-Tank fuel pump working fine.
  8. What size is the in tank pump?
  9. Original Stock Pump
  10. Stock Fuel Pump runs at 88LPH. That converts to only 23.25GPH. My inline t-rex was pumping at 50GPH.

    If I may use some common sense here, then I assume that running the car normal, driving slow, or driving mildly on the pedal for a few days shouldn't hurt. I am assuming this because under slow driving boost levels from the SC aren't a factor if at all.

    I also assume I need to be carefull speeding up from a dead stop and merging onto a highway for example as you tend to speed up quickly to not hinder other drivers speeds.

    Are my assumptions correct?
  11. Stock pump is good for 250 naturally aspirated HP.

    Note: For forced induction engines, the above power levels will be reduced because as the pressure required by the pump increases, the flow decreases. Every 1 PSI of boost require 1 PSI of additional fuel pressure to maintain the same flow rate of the injectors.
    In order to do proper fuel pump sizing, a fuel pump map is required, which shows flow rate versus delivery pressure.

    My recommendation would be to take the belt off the supercharger and re-route the air intake directly to the MAF. That will keep you out of trouble.
  12. If I take the belt off the SC, will that hurt the oil flow? My SC is not self lubed so it has 2 oil taps one for intake and one for drain back to oil pan. I'm assuming if the SC isn't turning it's not collecting oil and therefore it will be ok?
  13. Simple answer: Cap or plug the oil supply line and secure it out of the way. As long as the supercharger isn't turning, you won't need it.
    Just remember to reconnect it when you put the supercharger belt back on...
  14. Just ditch the trex completely and install a walbro gss340 in tank. You could also use the new aeromotive 340 (or whatever it's called), but with a stock block it's not real necessary.

    You may even be able to find the walbro local.
  15. Completely unnecessary to remove or cap the oil lines.

    That's what I did. I have the T-Rex sitting in a storage box.

    It's oiled from the engine pump. There's a nozzle that sprays a mist over all the internals. Gravity drains it back to the oil pan. Whether the SC spins or not makes no difference.
  16. I opted for the BBK 255lph in-tank pump. Thanks to all for your suggestions!

    blown88gt, I left the oil lines connected. I'm simply driving the car short distances and keeping the rpm's down below 3000. I wanted to test out my other mods until my new pump arrives.

    I'm hoping this new pump will install easy and work for long long time. I'm also hoping my gas tank is clean. My fuel filter had a lot of gunk in it when I changed so it could be another set back but my glass is always half full...
  17. Update. I drove for about 3 days on stock fuel pump and just kept the RPM's down. Never passed 2500 actually. Everything was fine. Drove great. Today I dropped the tank and replaced the stock with my new BBK 255LPH. Got that old pump out and started to examine and to my surprise the pump was NOT stock but had been replaced by PO at some point with a Walbro 155LPH... So, I was probably ok to run this thing a little harder than I did but not wide open. The 155 still isn't up to Vortech spec. They told me minimum 190LPH.

    View attachment 115879

    Never the less, good to know. So it's weird to me they put in a walbro 155 in the tank, then installed the T-Rex outside. :shrug:

    New pump installed now. Running great. Deleted the old t-rex but left all the wiring and zip tied it away just in case I want it back for some reason in the future. Who knows right..;)

    Thanks for all the help!