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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

Reply to
James B.
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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).
Reply to
Peter K L Milnes

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

Reply to
James B.

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

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User

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