Hi guys! I'm new here, literally just bought a blue 1985 Volvo 245 DL with a 4 spd overdrive transmission. During the test drive it ran great, then at the very end it started acting up. Heres what happens: car runs great, after idling for a minute or so it will start revving up and down, between 700 and 1300 rpms. Once you take off it lurches like crazy. Once it seems to build a little pressure it takes off and drives fine. It seems to be fuel pressure related. If you only let it idle for 25 seconds or so it will take off great. Its just after idling for a bit that it acts up. Thoughts? The PO thought it must be the pre pump? I'm completely new to Volvos so I'm lost.

 

I would check the fuel pressure regulator, try unplugging the vacuum line and see if there is any signs of fuel in there. Also check for vacuum leaks cracked hoses etc.


If its a fuel pump its most noticeable on the highway under a load then idling.