Need Help!

[Restorer72]

I need a 911 guru's help!. I have a 1970 911 2.2s that wont rev past 5800rpm. The car runs perfect, goes good but gets to 5800rpm and just wont rev anymore. I have tried:
Replacing spark plugs, plug leads, distributors, distributor cap, rotor button, points, electronic fuel pump, MFI pump, muffler, CDI box, coil, battery. I have removed the filters from the petrol tank and they are clean. The steel fuel lines from MFI pump to the injectors have been replaced. The injectors have been cleaned. I can drive the car but it just wont rev past 5800. If you put the car in neutral with the handbrake on it will rev all the way up to 7300rpm.

I will be grateful for ANY advice.
Restorer 72

[Early_S_Man]

So, the malfunction is only under load, while driving, right?

Sounds like a fuel delivery problem to me ...


Have you tested fuel pump delivered qty in 30 seconds in a large, clean, dry two or three liter soda bottle? The spec book says 900 - 1000 ml in 30 seconds.

Prepare the soda bottle by using a measuring cup to find the fill level at 900 ml and 1000 ml ... mark lines with a permanent marker.

[304065]

Fuel starvation. Did you replace the silver can filter? Did you hook up the lines correctly?

There's a failure mode of the MFI pumps that prevents revs over 5K but you have replaced yours?

[Restorer72]

yes i did test the fuel flow rate 1lt for 30 second and yes i have replaced the silver filter and i have tried swapping the line into the filter and made no difference thanks guy for your input any more suggestions

[304065]

Ok, there's a procedure known as CHECK MEASURE ADJUST which is a systematic diagnosis written by the factory to assist in troubleshooting MFI engines. I suggest you proceed systematically to identify the problem in accordance with CMA. You can download it free here:

Ultimate MFI resources thread