Fuel Pulsation Dampner Elimination
RX-7s made during this time frame had a small round device on the primary(lower)
fuel rail called a pulsation dampner, or PD/FPD for short. Often these
fail allowing raw fuel to be shot out, which then runs down the side of
the engine onto the hot exhaust manifold. Many junkyard rx-7s died a fiery
death because of this, and many owners have had their cars catch fire
spontaneously due to this. However, there is a simple and cheap permanent
fix with no side effects for the owner who wants to take the time to correct
the condition. Here are directions:
1. obtain a spare primary fuel rail from an 86-88 non turbo engine. Note
the FPD on one end, (the larger mushroom shaped part) and the banjo bolt
on the other end(hollow bolt). Remove the banjo bolt (banjo bolt size
is 12mm x 1.25) and discard the rail. See image 1.
2. Remove the primary rail from your car. You will need to remove the
intercooler(turbo models), upper intake, middle intake(nonturbo models),
and assorted hoses, cables, and wires to do so. The lower fuel rail is
bolted to the pass. Side of the block, where the intake mates to the engine.
3. remove your FPD from your fuel rail. See images 2 and 3.
4. install the banjo bolt you removed from the spare rail into your rail.
Be sure to use both copper crush washers and tighten this bolt down well.
See image 4.
Put it all back together. Be sure to get the fuel lines and injectors
seated and tight, and inspect for leaks. See image 5.