'92 240 hard start

joshyoder · Post by **joshyoder** » 05 Jan 2019, 22:39

my '92 240 is hard to start when the engine is cold. In hot weather it starts pretty easily, but if the temperature is below 60F it is nearly impossible. Engine idles very slowly and dies. If I press the accelerator it dies instantly. After several tries, lightly tapping the accelerator, I can get it revved up, then it runs fine. When the engine has warmed up it runs great.
The tank pump was dead, I replaced it. Idle improved if I pinched the fuel return from the regulator; so I replaced main pump and filter. I replaced the coolant temperature sensor, but that didn't change the problem. I am getting a coolant sensor fault code from the ignition computer, but not the ECU. I've tested the resistance on the wires that carry temp sensor signal to the ignition module and ecu. Both wires test proper resistance (2Kohms).
I don't know where to go from here. Should I try another temp sensor? I think I got the Bosch, but cant remember for sure. Is the ignition module defective? I'm thinking about opening it and looking for cracked solder joints. Does anyone have a spare they would sell me?

Post by **jimmy57** » 05 Jan 2019, 22:55

2K ohms on the coolant sensor circuit would be a good reading for something around 70F. what temp was the engine when you checked it?

joshyoder · Post by **joshyoder** » 05 Jan 2019, 23:05

Ambient air was about 65, and engine had only been running a few minutes. Another problem I forgot to list- at 65-70mph the engine starts sputtering if I press hard on the throttle. the car jolts pretty hard, feels like the engine is completely cutting out momentarily. I've replaced the throttle position sensor (twice, first one was defective.) Maybe I should try running the car with the tps disconnected and see if that changes?

dj_v70 · Post by **dj_v70** » 06 Jan 2019, 12:07

It sounds like low fuel pressure. I’d look at fuel pressure regulator.

joshyoder · Post by **joshyoder** » 06 Jan 2019, 19:44

replacing the pump and filter has improved performance at highway speed. Pinching the return line does not help the cold starting problem.

joshyoder · Post by **joshyoder** » 10 Jan 2019, 21:32

okay so I tried pinching the return line again tonight. After several tries it started and idled very slowly, nearly stalling. When I removed the clamp from the return line it died. I'll replace the pressure regulator before I try anything else.

joshyoder · Post by **joshyoder** » 09 Feb 2019, 13:55

okay, so I replaced the regulator and that hasn't solved the problem. Out of sheer desperation I opened the ignition control unit to look for a cracked solder joint or burned component. It looks fine. Any other suggestions? I'm desperate. It would really hurt my pride to take it to a professional.