Fluctuating MP on rear engine

[Ken MacLean]

Yesterday I was flying my T337C and began to experience fluctuating MP (22"-26")on the rear engine. I had been flying at FL220 and was doing descending holds to 12,000 when the problem appeared. OAT was -35 Fahrenheit, and no problem with the front.

I tried adjusting mixture (no effect) and throttle position (raised upper and lower limits of fluctuation range ). In descent to 8,000 the needle steadied, then below 7,000 fluctuation reappeared with fuel flow reading 12 GPM (front engine was 8.5). I went down to 4,000 and was able to continue to an uneventful landing with no further problems, except that the fuel flow remained stuck on 12 GPM (rear engine) even after shutdown.

All other indications were normal - EGT, oil pressure and temp and cylinder head temp.

During the worst of the fluctuations the engine seemed to be surging.

I remember reading a thread about folks with a similar problem that ended up being rather simple - some screw or something in the fuel control unit. Do I remember correctly? Any other ideas?

Thanks.