fuel pump??? 760T

Check the FPR before the fuel pumps. This is a well known failure on

AC

What does the tachometer do when it stalls? Does the needle ride down with the engine RPM or does it fall like a rock?

When the prepump or connecting hose between the prepump and outlet tube in the tank fail the car will stall religiously on left hand turns from about half empty and below. Often it will show a flat spot on hard acceleration. If the prepump has indeed filed it would be prudent to change the main pump as well since the repeated absence of fuel from the preump will have damaged the bearings in the main pump since they rely solely on fuel for lubrication.

Bob

I believe the tacho, just drops like a stone..

A common cause of ignition cutout (which will be the case if the tach does drop like a stone) in that vintage is the Hall effect sensor. IIRC the part runs a little under $200 US, but I lost the list Mike F posted so long ago about which model/years had the sensor in the distributor and which had them at the flywheel. The sensor can be very difficult to catch in the act, and many are diagnosed on the basis of "changed it - no more problem" or "changed it - still have problem." Symptoms are typically engine cutout any time it wants for as short or long as it wants, although some fail completely.

If the fuel pump is quitting the power will disappear somewhat smoothly, but if the ignition is quitting it jolts off and on - assuming there is an "on" :-)

Mike

It's not a fuel problem then. My first guess would be the hall sensor in the distributor, or depending on the year it could be the problem I had, a crumbling wiring harness. It's also possible the ignition power stage is failing.

Yikes, no you can order the hall sensor for about $45, not nearly so painful.

Turbos had the hall sensor up to and including 1989 model year (up to and including 1988 for non turbo). The ignition power stage is mounted on the inner fender on an aluminum plate just behind the left headlight. If your car is post hall sensor, the part that replaced it, the crank position sensor, suffers from similar problems. It's located in a bracket on the top of the bell housing.

That's good to know - it puts it in the range of being "shotgunnable" (replacement on suspicion). Where's a good source? I looked at IPD but didn't see it.

Mike

Both FCP Groton and alloemvolvoparts.com sell it I believe, I know at least one of them does. I forget who is cheaper but I shop between the two depending on what I'm getting.