Hi

I recently purchased a 1992 240 wagon with around 250K miles on it and have been having an issue with hesitation and stalling when I give it gas at idle. If I accelerate slowly it usually does fine, but when I try to accelerate quickly it bogs down and stalls. It idles fine, and runs good at highway speed. It seems slightly worse when started from cold, but still does it when warmed up too.

I have replaced the in tank pump which was dead, the fuel filter, plugs, wires, cap, rotor button, mass air sensor, O2 sensor, and new flame trap, I have cleaned the throttle body, and Idle air control valve and have fixed a few vacuum leaks. The Check Engine light is not currently on though I haven't checked for any codes (plan to do so today).

Any ideas on what to try next?

Thanks

 

OK I just checked the codes and got 3-2-2 (Mass Air Flow sensor burn-off signal missing or faulty (MAF wiring fault)), and 2-3-1 (Lambda control – too lean or too rich at part load). I cleared them and am going to go for a drive to see if they return.

 

The 2-3-1 code came back after a short drive

 

I think I figured it out. I noticed the vacuum line to the fuel pressure regulator was a different color than the other vacuum lines (bright blue) so I thought it had been replaced at some point. I pulled it off and it was very thin walled tubing. I replaced it with thicker walled tubing and no more hesitation. I’m thinking the old tubing was collapsing under vacuum and messing with the fuel pressure regulator.