I have a '91 240 that ran fine one day, and wouldn't start the next. It turns over fine, and it has spark, but isn't getting gas. I might add that the car is an hour away from home, and I'd much rather diagnose and fix it than have it towed to a dealer. Here's what I've done so far in my attempt to diagnose it.

The fuel pumps won't operate. I checked them by jumping fuses 4 and 6 and they both worked, and the car ran although at high idle.

I next checked the relay. Actually, I swapped relays with my other '91
240 and determined that the relay was not the problem; however, there is no
juice at terminal 87/2.

I next checked the diagnostic box for error codes (with the plug in
socket no. 2). I recieved no signal - just steady light. I swapped the
diagnostic box from my other car and the same thing happened. I performed the diagnostics for the ignition and it had an error code stating that the load signal is missing from the ECU.

Next, I tested all of the inputs to the ECU. A few appear to be faulty -
the upshift light ground wire, the AC switch, and the oxygen sensor - but these
shouldn't result in a no-run condition. The grounds appear to be okay, too. I
unplugged the air mass meter to determine if it was the culprit, but no luck.

My Bentley manual refers to an in-line fuse, but my '91 doesn't appear to
have this, or I'm not recognizing it.

I'm running out of ideas, other than the ECU itself may be faulty. I hoped
to swap ECU's between my two '91 240's, but, alas, one has an LH-2.4 and the faulty one is an LH-3.1. As luck would have it, the price for a used or rebuilt
LH-3.1 is much higher than the more common LH-2.4, so I'm trying to diagnose this correctly before ordering a new or rebuilt ECU.

If anyone has any other ideas I'd appreciate hearing them. Also, if anyone
knows of a good source for ECU's please let me know.

Please copy replies to my email: dragnfly@bitstream.net

Thanks!

Tom MacDonald
Minneapolis, MN