Bahman

I have a 1972 911E Targa in mostly original condition. The engine has developed a problem which exhibits itself by cutting out, stumbling, coughing, spitting, and almost dying when throttle is depressed rapidly, with engine at normal operating temperatures. I have done the following, but none has helped:

- Replaced fuel filters (2) and drained fuel tank (it's clean)

- Replaced fuel pump and lines

- Replaced all electrical parts (coil, dist cap, rotor, points, plug wires, connectors and plugs)

- The MFI pump was rebuilt and calibrated a few years ago; have not had any issues

- The ignition timing is spot on

I have gone through most of the issues addressed in Rennlist in this forum but cannot find any applicable solution. Would appreciate any information that can shed some light on this issue.
18 W. Mountain Street, Kernersville, NC 27284

myflat6

Was this happening before the coil replacement? I have had issues with replacement coils causing this behavior.

Bahman

myflat6
This was happening before I replace the coil. The new coil is factory original OEM, from dealer.

raspritz

There could be dirt or rust in the hard lines running through the tunnel, which are very difficult to plumb or replace. Though you have gone through all the usual suspects, to quote Sherlock Holmes, "Eliminate all other factors, and the one which remains must be the truth."

Spyerx

Fuel pressure validated?
Checked injectors?
Checked wiring at engine harness, ground strap, fuel pump?

Bahman

raspritz
I have replaced all rubber/flexible fuel lines, but not the solid ones in the floor. Good suggestion. Will check and update the post.

Spyerx
Fuel pressure and injectors are good. There is not grounding of the fuel pump, except for the sealed harness (2-wires) that plugs into it for power. The connection is good.

Thank yo both for suggestions.

Bahman

“Thank you” to all who helped by providing advice & suggestions.

I narrowed the problem to a faulty ignition combo of points, coil and CDI box. CDI was the culprit, but I replaced the points and coil again.

the engine now runs flawlessly, as it used to.

Thanks again. 😊

Super90

As my local guru Ed Mayo says, 95% of drivability/fuel/carb/mfi problems are usually ignition issues.

Glad you found it !!

Bahman

Super90,
25 years of my car’s 48 years were spent in Dallas area, and I came to recognize and appreciate Ed Mayo’s mastery of 911 expertise. It was he who guided me remotely (I now live in NC) to look at the ignition area, especially the CDI.

Comforting to know maestros like Ed exist, and generously share their knowledge.

Cheers,
Bahman

Gdub

Always love a happy ending.

Al Gebra

You might want to kill the points and go with a more modern replacement.