After thinking about it I decided not to replace the check valve.

I cleaned (rinsed) the idle control motor and seem to have corrected the problem.

I had the same problem removing the idle control motor as some others have had. The nuts on the back of the plate were loose and I was unable to (not small enough 10mm wrench and hands) secure them while loosening the 3 bolts. The idle control motor is (like the flame trap) not readily accessible with the intake manifold in place. After about 30 minutes I just gave up.

Instead I removed the hose from the air filter hose (just ahead of the throttle body) and poured about 4oz of throttle body cleaner down it. I let it sit for a couple of minutes then started engine.

Probably just a temporary fix but initial idle problem is now cured and warm idle is smoother at this time.

Given the gum and bailing wire approach I used I expect the problem reoccur. When it does I will make a better effort at removing the ICM for workbench cleaning or replacement.

Thanks to all for suggestions.
Howard

Hi Howard:

This sounds more like a failed Fuel Pump Check Valve issue to me. I had the same issues with my car several years ago, and the problems went away when I replaced this $16 part. Available from FCP Groton, it does not take long to install.

http://www.fcpgroton.com/product-exec/product_id/5147/nm/Volvo_240_Fuel_Pump_Check_Valve_1985_1993_Bosch_/category_id/149

It's easy to check the fuel pressure regulator under the hood, just remove the vacuum line, and check for gasoline or a very strong gasoline odor. If that's not the issue, then I would check the check valve on the fuel pump. Did your new fuel pump come with a new one, or did you re-use the old one?

The check valve keeps fuel in the fuel line so that you have full pressure when you start your car. If the valve has failed, after 30-60 seconds, your system has been re-pressurized, and all is back to normal, so no stalling.

Be sure to follow up and let us know what you find out.
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If it needs to be maintained, repaired or replaced on a 1990 240, I've probably done it. '90 240DL, 323,320 miles, will she make it to 400K ?? >>You haven't really worked on a car until you draw blood<< :-}