2000 s40 barely running

jared455 · Post by **jared455** » 03 Sep 2011, 15:14

Two days ago on my way home my car stated losing power. The rpms would drop every time I would press on the gas pedal. I was able to limp it home by barely giving it any gas. Since then I have cleaned the throttle body, the IAC, the TPS, checked the FPR and replaced the fuel pump and fuel filter. Also checked the fuel pressure and it is at around 12 psi at the fuel rail and also right before the fuel filter coming right off the sending unit which seems rather low. Also took out and cleaned the spark plugs which were pretty black. After all that work the car will start but whenever I give it gas the rpms drop and it will not run steady at all. I pulled off the hose coming off the intercooler going into the throttle body and sprayed starting fluid into the intake and it wakes the motor right up. Also checked the plugs after just a few minutes of running the car and they have quite a bit of carbon build up on them after running it only a short amount of time. It seems like there is a fuel delivery problem but what else could be the cause??

joolsax · Post by **joolsax** » 09 Sep 2011, 03:52

Hi, there tempremental cars , had a simelar problem with the s40 auto matic i drive, revs hunting, give it the gas cut's out,
have you tryed spraying cleaner in to the stepper motor located on the front of the engine? also the vacume pipes cleaning?
i had that done by my mechanic friend job sorted, hope that vhelps you out

jared455 · Post by **jared455** » 10 Sep 2011, 22:41

So after days of research and trying different things to fix the issue I narrowed it down to the fuel pressure regulator in the actual sending unit. What happened was the FPR metal housing had broke loose from the plastic housing on the return line. The fuel was bypassing the FPR and it caused the pressure to drop dramatically. In testing the part it completely broke away from the FPR housing and obviously needed to be replaced. After finding a used sending unit on ebay I replaced the part and the car started up and ran even better than before since it now had a new fuel filter, clean throttle body, IAC, and TPS. I hope this will help someone that might have the same problem as I did.