Warm Up Regulator??!!

Hi folks........I need some much needed help on this one. I had my 15K service, valves, plugs, points, cap, etc., and headed out for a two day road trip. Car ran great after warm up but once I shut down for 20+ minutes and restarted I was getting some backfiring and HARD start. On shorter intervals (just after fill up) it started right up. I do not know how to diagnose the problem but hear the WUR is usually the culprit. That brings to this forum what my local Porsche Parts guy said. "The WUR on the 911T (1973.5 model)was not good at holding pressures"; therefore, a Porsche tech. bulletin in 1983 recommended an update of the WUR to a 1975+ unit. A retrofit kit would have to be used and a slight body modification done for the right fit. I understand Bosch no longer sells the original WUR for that model. What is the best way to test for the problem and what in the CIS usually is attributed to this problem, bad springs? Its driving me nut!!!! and if it were not for the pop off valve I could have a garage full of airboxes..

Thanks
Bob
1973 911T

Hard start problems after a hot soak usually point to the accumulator, not the WUR. It's the accumulators job to hold system pressure for up to 20 minutes after the engine is shut off.

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Bill Krause
'79 911SC Euro

But even a good accumulator is no match for a leaking fuel pump check valve which is the most common reason for failing to hold residual pressure.

Regards,

Joe