Warm running issues - 82 ROW SC

[chockymonster]

I've been trying to get my head around a rough running issue I have at the moment.

The car starts on the button and runs perfectly, no idle hunt, after a few minutes the idle drops off and starts to hunt and normally stalls.
When driving I have to keep the revs up if I'm coming up to a junction as it will die on me. On deceleration I get the occasional backfire.

Searching the boards gives loads of things to look at but I'm not 100% sure where to actually start.

When I bought the car it had been laid up for 13 years and had a very similar running issue which I traced to the fuse box in the front. It was as good as gold all last year but come this spring she's running badly again.

Any suggestions of where to start would be appreciated.

I've checked fuel relay voltage, all is as it should be.
I've read the sections in the Bentley manual but it might as well be written in a foreign language! I've got a fuel pressure test kit to text with but I'm guessing a bit of handholding advice would be helpful!

[Paulporsche]

It sounds like your control pressure is correct for a cold start, but as your WUR moves through its cycle to its warm setting the control pressure becomes too low, resulting in a too rich mixture which has the symptom of idle hunting that you described.

I would let the engine get cold, hook up the fuel gauge, take note of the ambient temperature and start the test. Then, over the next five minutes or so, record the control pressures.

Post the findings here or compare them with the chart for your WUR.