QuestionQUESTION: there My 96 850 will not start, I checked the fuel pump it runs, there is pressure at fuel rail, dont know how much. I hooked up timing light to coil wire to dist. no spark or light while cranking.Sometimes it will try to start but not now. I had this problem before but it cleared up. On the rare occasion it starts it runs fine. By the way there are no trouble codes.
I have read some of your answers from before and was wondering how the system knows there is no gas pressure, because you stated "no pressure sometimes means no spark" I subscribe to ALLDATA and could find any info on no gas press, I have noted that it says no cam position signal no spark.
ANSWER: Robert,
If there is fuel and no spark check for fault codes like the cam or flywheel sensor. If no codes then look at the coil and power pack. They will not set codes. If the fuel pump relay goes bad it will not complete the circuit for the spark.
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QUESTION: I have checked the fuel relay starts the pump and it runs I have 40 psi at the fuel rail. What tells the system there is no fuel and how do you check it. Like I stated there are no codes 121 131 314
ANSWER: Robert,
No code(s) no spark look at the coil and the cap and rotor. If there is spark and still no start I have seen many that the fuel has washed out the oil in the rings and not enough compression. At that point I pull the plugs and give a squirt of oil to all the cylinders.
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QUESTION: Hi again Ray
Let me start from the beginning. I have work on car all my life but not too much on electronic ignition, and never on a Volvo. But I also have 40 years as a service tech on HVAC and digital control systems for Johnson Controls.
I bought the car 1 month ago. It had some hard starting problems may once a day,then it got worse. Now it may start or not. It has a mind of its own. I have installed new cap, rotor and plugs 1 week ago. I have tried everything. I have disconnected the can sensor, the rpm sensor one at a time and checked to see if error codes appeared and they did I have cleared the codes and right now when I check it says 1 1 1 . I have checked the primary and secondary of the coil and both are good. I have checked the wiring as described by the ALLDATA sheets and they are OK. I do not know what the signals the power stage on the coil to spark I have tried 3 differant coil and can not belive all are bad, all three start the car when the car wants to. All that I do know when I hook up my timing light around the coil wire to the distributor it dose not flash at all.Is the problem in the control module telling the coil to fire? As far as taking it to the dealer I have heard too many horror stories about them. Maybe I`ll call the cae Christene, if you remember the movie
Thanks once again for your time
Rob 1
AnswerRobert,
I guess that the control unit could be bad, I haven't had one yet. I have seen bad wire under the control unit go bad. I have seen intermittent cam and flywheel sensors. I have seen MAF sensors that are bad and do not set a fault code. What about when the car will not start unplug the MAF and see what happens. To the best of my knowledge the flywheel pick up is the signal for the spark. Could the flywheel be damaged? One of the windows in it bent. When it will not start can you hook up the Vantage and back probe the flywheel pick up for a reading/waveform?
