First, let me say that this "brick" (1987 240 [August 1986]) has been a super-car! Bosch Jetrontic LH 2.2? We bought it for $2K back in 2000, and it owes us nothing!! Miles have to be over 200K, odometer stopped years ago at 146K. But, lately I've had to do more and more to keep it happy. The last California Smog test cost us almost $500, so I'd like to get a few more miles out of it.

About 4 years ago I (successfully, I believe) installed a NEW wiring harness, the one with the junction block at the firewall. It solved a lot of "gremlins",
but I did NOT swap out the harness which is routed under the crank
pulley, and goes to the Ignition Control Unit. Is this a place to start?
Crumbling wiring insulation?

The situation; The Grey Ghost sat for almost two weeks, and when I drove
it around the block, it ran for about 5 minutes, then died. Now, I cannot
get it to fire up. ZIP, not a whimper. Cranks like a MONSTER, but otherwise,...In the past it would sometimes die at a light, or
somewhere, after running, but would always start again. Once it was
warmed up, it was (usually) quite happy. I've gone through the archives,
but haven't found quite this set of symptoms, so,...

My suspicion is that it has been running DESPITE itself, i.e. it has
some unresolved (electrical?) issues which weren't quite enough to keep
it down. But the car always seemed to run for us. Until recently.
Some symptoms, but not with any logic, or relativity;

A.) The fuel pumps will hum even though I remove the 4 and 6 fuses!

B.) The in-tank (pre-)pump will work when removed from the car, but NOT when
installed. I guess the main pump has been doing all the work?

C.) The pump seem to run continuously when the ignition is turned on,
i.e. won't shut off after the correct pressure has been reached.
Is that SOP?

D.) The unit (air control valve?) under the manifold "buzzes"
continuously, and I can feel it vibrate. Don't remember that as a
feature, back in the day.

E.) I do have fuel to the system, as evidenced by opening the union where
the line enters the rail from the pump.

F.) I have NO spark at the end of the coil primary cable, when grounded
to the engine block, and the starter cranking. I have 12 Volts to the
#15 terminal, BUT when I crank the engine, the #1 terminal shows 12
volts, but doesn't go out completely. It only glows brightly, then less
bright. I have NO spark at the end of the coil primary cable, when
grounded to the engine block, and the starter cranking.


I have access to a bunch of extra parts from a friend's dead 240, and
a good junkyard nearby. This time I have done the following;
1.) NEW battery (just to rule it out), cleaned up the cables and the
poles.

2.) replaced the 25 amp fuse and holder (the one next to the battery). Have juice at both ends.

3.) replaced the distributor (with a known good used one). Cleaned up
the cap & rotor, and tested the spark plug wires. Hall sensor looks like it's in working order, with clean intact wires

4.) swapped the coil out for known good used one, Bosch.

5.) I have swapped out the ECU (under the dash, at the passenger
footwell) with the correct (XXXXX-544-known good used) one.

6.) swapped out the air control valve (with a known good one, I think)

7.) swapped out the fuel pump relay (under the dash, at right). I have a
bunch of spares, so ONE of them has to be in working order, no? They
"click" when the ignition is switched on. The GREEN/BLUE wire (terminal
#86/2) has been spliced with a black wire to chassis ground). Car
wouldn't previously run without it.

From what I understand of the ignition system, the Ignition Control Unit
(behind the right headlight) has to send a signal to the coil, and the
ECU (under the dash @ right). So, is that ICU my next "culprit"? How do I
diagnose an Ignition Control Unit, aside from buying a new one? What are
the chances that the wiring harness between the left side of the engine,
UNDER the crank pulley to the ICU is defective?

I have a '91 240, but am reluctant to use it as a "donor" car for test parts, even if they are compatible.

So, what do I have here, guys? A can of (electrical) worms, or just a
defective part? I promise to post the (soon to be successful) results
back to the BB. I've been guilty of not doing that in the past. I'm more
at home with the really early pushrod Volvos.