I recently purchased a 1987 Volvo 240dl. I literally found it as a couple was pushing it out of the road and I offered to buy it from them. The couple pulled it home and I went to their house later that evening and purchased the car. When I got in it, I turned the key, it cranked but didn't start. I did that twice and then it stated on the third time. It sounded great. I drove it home, (about 10 miles) with no problems. The next day it started just fine and I drove it around a little. Then a couple of more days venturing further from the house each time. No problems. I went ahead and got it licensed and drove it to work. Halfway to work I started up a big hill and it started to sputter. By the time I got to the top it died and wouldn't restart. I took the day off and replaced the main fuel pump and filter. Started fine, and I drove it home. Next day: went to work, almost made it to the big hill and it sputtered and died. wouldn't start. After work I replaced the main fuel pump relay and it still wouldn't start. I jumpered the main fuel pump and the in tank fuel pump at the fuse box, (Number 4 to number 6). It started and I drove it home.

Now I'm trying to figure out how to trouble shoot this further. How do I read codes on this car? What is the best way to proceed with trouble shooting this problem?