Bad Injector O Ring Question

Discussion in 'Fox 5.0 Mustang Tech' started by flashback87, Jul 28, 2014.

  1. Can someone tell me what bad injector o rings look like. I have my injectors out and i don't see any cracks but they move around kind of freely. I am trying to diagnose sumble/hesitation under 2.000 rpm. when i installed my explorer motor i never changed out these o rings.

  2. Are they hard or still plyable?
  3. i would say more pliable than hard but they are pretty dirty and some are wet. The inector by the #5 cylinder is the most wet and the o ring on the injector behind that one has a lot of "up and down" play in it. the rest fit pretty snug.

  4. Dohner90 likes this.
  5. Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $3-$4 per kit.. The following are listed at the Borg-Warner site ( ) as being resellers of Borg-Warner parts: or or or

    Most of the links above have store locators for find a store in your area.

    Use motor oil on the O rings when you re-assemble them & everything will slide into place. The gasoline will wash away any excess oil that gets in the wrong places and it will burn up in the combustion chamber.

    The pintle caps fit either injectors with a pin sticking out the injector end or 4 with more tiny holes in the injector end
    The pintle caps hold the O ring in place and keep it from sliding off and into the manifold. If the correct pintle caps are used, they do not have any effect on the injector spray pattern or engine performance.

    Heating the pintle caps in boiling water makes it much easier to install them.
  6. Replace them! And have an extinguisher ready on start up. I've learned that one the hard way.
  7. Thanks! i replaced them but it did not help the low rpm hesitation. I will start a new thread to see if anyone has some insight.