4.6l (1999) Fuel Rail Screws On New Manifold.

Discussion in 'SN95 4.6L Mustang Tech' started by Bill9000, Jul 28, 2014.

  1. Hey y'all, I just had a quick question... I had to replace a cracked intake manifold on my 99 GT. It's dont and back together, havent started it yet, as I need a new alternator bracket... but my question is, the fuel rail screws... the factory maniflold had metal inserts and screws holding the fuel rail down and the injectors in place... the new plastic manifold has self tapping screws... all is well except for one of the screws doesn't tighten, just keeps turning... it's sort of snug... but not tight as I woudl like it to be considering it's fuel... the rail feels solid and doesn't move, I'm just concerned about high fuel pressure and a fuel leak? as in the vibration of the engine working it loose? should I be concerned?

  2. What intake did you buy for a replacement? Sounds like you got the Dorman which is designed to work on both PI engines (99-04) and the NPI (96-98) so you will have to use the self taping screws to mount the rails and the cops. Also before you do tap it and start the engine consider removing it and taking it back for your money and buy the FRPP OEM PI intake from some where like Summit Racing or American Muscle. I do not know if there is any performance loss with the Dorman intake but side by side tbe Dorman looks like it has smaller intake runners and is not as deep to accomodate NPI motors coolant lines that run under it in the vally. Basically the FRPP intake is OEM PI with the updated coolant x-over for durability. You will still need the updated alt. Bracket (which i thought the Dorman came with) (Dorman gaskets are horible too) which you can snag from any 4.6 car engine that has had a updated intake replacment. I got one off a Crown Vic when i did mine.

    Please dont get the idea im trying to step on your toes here but rather trying inform you.
  3. Thanks for the reply, I was at Summit (I am fortunate to live within 20 minutes) and I ended up getting the Dorman one, as the other was a lot more expensive... it's already installed and back together minus the alternator bracket... I would've liked to buy some better intake but, this situation came at a terrible time. LOL

    That said, all the self tapping screws for the fuel rail are fine except one, that doesnt REALLY tighten as I would like it to.... it just turns.... the rail feels good and secure... but I"m concerned after running it... I know the Fuel system is likely high pressure, but that would be "to" the injectors, there's probably not a ton of force pushing from the injectors upward on the rail, otherwise, they'd have a better mounting system for the rail?
  4. The Dorman replacement WILL cost you power.
  5. I wish I lived that close to summit. The rails run at around 40-42 PSI give or take. Maybe you could try a slightly bigger self tap screw to see if you can get it tighter. I think Dorman did it that way to work for the 96-2004 4.6L cars. There are a few different arrangements.
  6. awesome thanks.
    I loc tite the screw in there with hi temp, loc tite and it seems to stay good, but now I have a different issue, the car is running really bad since being back together, sounds like it has a burnt valve or something of that nature, has a bad flat spot if you try to rev it and pops and is generally running poor...

    very sporatic popping type sound, here's a cell vid:

    View: http://youtu.be/EXwPBYjuU-o

    thanks for your help!
  7. Has the CEL came on yet? Since you removed everything to replace the intake i would start with the COPS. Check all the plugs to the injectors and the COPS
  8. The CEL is always one because of my off road X pipe, but I have since fixed this issue, I bought a brand new set of coil packs... and replaced them and the plugs and all runs perfect now. Interesting thing I was able to buy a set of Accel high performance coil packs for about HALF the cost of OEM ones even from Napa... crazy!

    thanks for the help! :)