My 1990 760 turbo wagon with 240K is still having an intermittent stalling issue that is getting worse. I have followed the FAQ's and my Volvo wiring diagram (124 pages!). I have the version of an intermitent stall where the tach goes instantly to 0. It always happens on the freeway where all I can do is pull over and wait for the car to restart. The only code I get is a 144 from the EZK port.

Here is what I have done so far.

Swapped the radio suppression relay with the fan relay (they are identical part #'s on my car).

Resoldered the the FI relay (I have no fuel pump relay) and then resoldered the radio suppression and fan relays because I could.

Replaced the power stage and flywheel sensor.

Cleaned all grounds.

Checked all effected fuses.

I noticed the fuel pump continues to run with the key in position II even after the customary 5 seconds so I pulled the FI relay again to look for bridged solder traces, but found none.

Now for the questions:

Could I have cooked something in the FI relay while resoldering it that would cause it not to shut off after initial pressurization?

What controls the the timing of the intial pressurization by the fuel pump? Is it the FI computer or the relay itself?

Where do I go from here? The problem is getting worse and since it always happens on the freeway, I cannot jump out and do diagnostics.

With the exception of a broken park pawl in my 1982 240, I have never let a Volvo problem beat me, but this one has me stumped. All the clues point to either a bad FI relay or a bad radio suppression relay, but resoldering these relays has always fixed my problem in the past.

Onkel Udo