I thought I'd share my experience getting my beloved, purchased-brand-new 1981 Black/Grey GLT Turbo - the God Father of Volvo's entry into the performance market (Turbo and Volvo in the same sentence?) back in shape after having been relegated to convalescence. I was having several problems with the car that were annoying - hard warm starting, lack of power and poor fuel mileage. After Volvo quoted me over $1,500.00 dollars, I thought I'd repair it myself. Here is what has to happen. Remedial: 1. The fuel filter must be replaced, 2. ALL vacuum lines must be replaced and clamped and 3. The fuel injector seals must be replaced. (This is the foundation upon which to proceed). Hard starts: The check valve on the fuel pump is always cited as the first culprit; however, it is robust and not the first thing to fail. The frequency valve is. It will work but also leak back pressure to the return line directly at rest. The next problem is also hard start related but addresss the lack of power under boost issue. This is control pressure regulator related. The regulator controls fuel pressure in the warm up sequence as well as controlling pressure under load. The rubber in it will fail over time, the pressure becomes unstable and will not perform it's pressure-related function required under boost. (It is imperative that the vacuum lines and air check valve are working). Lastly, there are two little o-rings in the Fuel Pressure Regulator assembly (one inside the fuel distributor, that should be checked). These can be turned over and re-used. They are not super critical and mine were fine at 23 years. This can all be done without fuel pressure gauges (although I bought one) if one does not alter the basic system pressure (the shims in the Fuel Pressure Regulator assembly. The cold start valve can contriute to the problem and can be replaced if the problem persists. Ignition: the Bosch ignition is very robust. The one thing that should be checked is the clearance inside the distributor between the sensor plates (20mm)...the relays and sensors are very robust. Tune to specification.

I Hope this helps you. This is applicable to the 240s (the control pressure regulation varied every few years but the principals are the same).