740 wouldn't crank-black shiny plugs

Last Friday morning my '91 740 would not crank. I checked fuel pump
fuse,fuel pump relay, and sounded like fuel pump was buzzing with ignition
on.
Car turned over but wouldn't engage.
As last resort I pulled #4 plug(Bosch) and it was black and the tip black
and shiny. plugs had only been in car about 6 weeks. Tried putting new plug
in car and voila...car cranked. Went ahead and changed the other three. two
smelled like there was gas on the threads. all the plugs were black .
Question: what would cause this?
I'm getting a 2-3-3- code but have been getting this intermittently. Just
cleaned the idle control valve to see if this would help with other problem.
Mechanic has sprayed around the intake to see if there are leaks and there
do not appear to be.
Please help.
Thanks for your time.
James

 

2-3-3 is Adaptive idling control valve signal absent or faulty. Thi smeans
that the wiring or connector has become loose (intermittent). As well as
thoroughly cleaning the Idle Air Control Valve, you should also ensure that
the whole inlet tract (filter to manifold) is thoroughly clean including MAF
and throttle body. Should take almost a whole can of carb cleaner for the
throttle body. Then reset the idle setting and synchronise the throttle
switch. The whole cleaning up of the inlet tract should be done every two
years to keep the system running fine.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).

 

Thanks a lot Peter. I will check the connector and wiring. I have had this
problem before.
But that would not cause the car not to crank and get a quick build-up of
black deposits in the spark plug?
Thanks,
James

 

Make sure the fuel pressure regulator isn't dumping raw fuel into the
manifold. Pull the vacuum line off and check for fuel. There should be
none there.

Bob