Thanks everyone! It is time for today's episode of Dave guesses at FI problems...

Again following the Volvo Problem Solver, I check voltages and resistance at the AMM. Following the book and Art's good advice, I did this with the connector on the AMM, the boot pulled back, and (for voltages only) with the key in the on position. My results seem to match expectations ok:

1. The yellow wire (term 12) shows 2.27v and this is in the high range of 0-2.6v.

2. The red/white wire (term 7) shows 1.57v right in the middle of the range 1.2-3.5v.

3. The black (term 36) and green/yellow (term 6) are both grounds. So no voltage but both show continuity to ground individually and continuity to each other.

4. The orange wire (term 9) shows battery voltage 12.8v as expected.

5. The white wire (term 8) has no voltage spec in the book but I got minimal of .02v.

With the same setup except with the engine running I tested voltages:

1. The yellow wire still looks good and as I turn the AMM screw the voltages change within the expected range. So whatever is attached to the screw seems to work right.

2. The red/white wire show 4.15v at idle (which is low and rough) and this increases if I engage the throttle. This is far over what I expect from the book which says 2.7v at idle and 3.5v at 3500 rpm. Could it be that the AMM is trying to send a powerful signal to the controller to lean the mixture out? It is very rich and smelly despite everything.

With the same setup but the key off entirely I tested resistance:

1. Between terms 6 (green/yellow) and 12 (yellow) the book says 0 to 1K ohms. My readings (using the 2k range on the meter) were .280 to .363 so I think that is basically ok.

2. Between terms 6 (green/yellow) and 36 (black) - both grounds - the book says 2.6 to 4.0 ohms. On the 200 range on the meter, I get .1 to .3 ohms. I am not sure how to interpret this.

Then I decided to follow the suggestion made to check the coolant temp sensor under #3 intake. The book says to find the blue wire in the big, tape-wrapped wiring harness along the firewall. And then to probe it with a needle and check the voltage between it and ground with the key on (engine not running). The book says 0.1v with the engine hot and 3.2v at 20 degrees. It also says a voltage of 4.5v is bad sensor, disconnected, bad wire, or bad terminals. I get .45v. The engine is not very hot since only ran a few minutes while testing above. So maybe this is an ok reading?

I appreciate your comments on these findings.

Thanks