'92 740 suddenly dies.....

[geronimo]

It will be running fine, and then it just shuts off. Usually after it
sits there for a day, it will start again. Thought it was fuel pump
or pressure problem. It has a new fuel pump (not the one in tank...the
other one), filter, and a new fuel control relay. The plugs are firing
after it dies, its not ignition. The car has been with a very
exerienced pro mechanic now for over 2 weeks, and he can't figure it
out. NO codes are set. The mechanic says it still has fuel pressure
when it dies. He pulled out one or more plugs, and said that they are
soaked with gas, so he thinks the engine is flooding out. I didn't
think this would happen with injected engines....it just dying like
you switched off the ignition key.

If I remember right, this car has a separate fuel control (Jetronic)
computer module. (or maybe I'm confusing with my 88 Camry?) Maybe if
it is intmt. failing, the injectors would be stuck open, or open way
too long, flooding the cylinders with gas? But there is no code being
set for a faulty fuel ctrl computer. It costs big bucks to buy a new
one, and then we might find its not that!

I don't know if the mechanic has put noid lights on the injectors when
it has failed, that is what I'd do...and try reseating the ECM
connector if the noid lights don't indicate a failure.

Ideas?

 

[James Sweet]

It will be running fine, and then it just shuts off. Usually after it
sits there for a day, it will start again. Thought it was fuel pump
or pressure problem. It has a new fuel pump (not the one in tank...the
other one), filter, and a new fuel control relay. The plugs are firing
after it dies, its not ignition. The car has been with a very
exerienced pro mechanic now for over 2 weeks, and he can't figure it
out. NO codes are set. The mechanic says it still has fuel pressure
when it dies. He pulled out one or more plugs, and said that they are
soaked with gas, so he thinks the engine is flooding out. I didn't
think this would happen with injected engines....it just dying like
you switched off the ignition key.

If I remember right, this car has a separate fuel control (Jetronic)
computer module. (or maybe I'm confusing with my 88 Camry?) Maybe if
it is intmt. failing, the injectors would be stuck open, or open way
too long, flooding the cylinders with gas? But there is no code being
set for a faulty fuel ctrl computer. It costs big bucks to buy a new
one, and then we might find its not that!

I don't know if the mechanic has put noid lights on the injectors when
it has failed, that is what I'd do...and try reseating the ECM
connector if the noid lights don't indicate a failure.

Ideas?

When it dies, try unplugging the air mass meter and see if it starts
back up. That can fail in a way that makes the mixture go full rich,
though it's not common.

 

[Perry Noid]

I think your car is similar to my '89 240... I had a problem with it running
erratically a year or so ago. Replaced the fuel pump, still wouldn't run
reliably. No codes. Then I checked the large plug-in fuse located along the
left (driver's) fender, right near the spark coil. It is apparently the main
fuse for the engine computer and such. Turned out the socket it was plugged
into had broken apart! I was able to push the connectors back onto the fuse
spades, and the car ran (and has been running) fine since. I know from
experience that if you pull the fuse, you turn off the CHECK ENGINE light
and also lose the codes, so perhaps your problem is similar? Wouldn't hurt
to check the fuse, socket, and associated wiring anyway.... I think it is
about 30 amp, and mounted at the top of the fender, right above the
wheel.....