I recently bought a 1976 911 with the stock 2.7 motor in it. Took a risk had zero paperwork or history, but the engine ran very well until recently. Some weeks ago, noticed harder starting then usual and rough idling. Also sounds like it is “missing” when revved. So I thought a “tune up” was in order. I replaced the cap, rotor, plugs and wires. Still running the same. Bought a fuel pressure test kit and was unable to proceed because of multiple fuel leaks. The Nylon fuel line fittings had rust on them and apparently once I broke them loose, now leaked. So I bought all new fuel lines, banjo fittings, and while I was at it, new fuel injectors, sleeves, and o rings. Starting it up, and same rough running. So I started looking for air leaks. Did a smoke test and found zero leaks anywhere. Also replaced the fuel pump, fuel filter, and the fuel accumulator.
Did a re-test of the fuel pressures and here are my results.
System pressure. 4.5 bar.
Cold pressure. 1.5 bar (20psi) graph shows should be 1.7? WUR power disconnected.
Warm pressure 3.1 bar (45psi). With WUR plugged in.
Pressures seem pretty close to in range other then the cold pressure, but may even run worse when warm.
So I’m back to ignition. Re-wired some sloppy wiring around the distributor and installed a pertronix electronic ignition. Still runs rough.
Maybe a bad coil? I checked the resistance between the two posts and got 0.8, so I think that is in spec. Could the CDI cause this problem? Maybe I missed an air leak or 5? Haha. Also seems like its running rich, lots of smoke at startup and is “spitting” oily moisture out the tailpipe.
I’m stumped, low on funds, could use some help!
