Hi, my 960 will crank but will not start. We already checked the timing belt, cam sensor, crank sensor and fuel and all are fine. The spark on the spark plug is almost unnoticeable, there is 12 volts on the coils. About a year ago it did the same thig but it will do it sometimes only, and after some minutes it would start, but then it stop doing it, it started perfectly everytime. now its been three weeks. can somebody help me?

What year is it? Are there any codes stored? Read it even if the check engine light is not lit up.

Did you check the spark on all the cylinders?

There is a test socket at the back of the head where the cam sensor and rpm sensor connect, this socket is a single female wire, white and red I think. A volt meter connected there and ground should read battery voltage, this current is coming from the ignition relay.

Also a bad Air Mass meter could cause a no start condition, with the ignition off, disconnect and try starting, if it is bad it should start, stumble for a while and then go in limp home mode.
Is the little hose from the idle speed motor attached correctly, sometimes a back fire will dislodge it enough to look as though it is still on but is letting air in.

You don't state what the year of the vehicle is, but my '94 is very prone to electrical malfunctions due to corrosion on the connectors, in my opinion they are weather resistant not weather proof. Annual cleaning and tightening is required especially where there may be salt in the air.

Another source of faults is the big block connector on the left wheel hump, under the black box. This would be only for '94 and older, the newer cars split up that connection into smaller ones throughout the engine compartment.

Check and clean all of your ground points, by the battery, the back of the head, and the one on the driverside engine mount bracket.

When the ignition is left on, does the idle speed motor making a humming noise? Take it off the car and gently twist it, does the valve body hit it stop limits internally? It will make a slight clicking noise at each end of the twisting action.

I would also clean the connections to the power stages, they are located on each side of the lower intake manifold, for and aft of the ball shaped area.

Also depending on the year, the ignition relay and the injection relay are located on the driverside, under the hood along the top of the fender edge. You can swap those, they are the same part#s, if your problem becomes fuel related and your spark is strong now, then it is one of those relays.

Report back with your findings.

DanR '94 964 332,000 miles (98,000 on the new engine)

Thanks DanR, I will try all this and report back.

I forgot to mention its a '93 960.

Hi again,

I changed both power stages and cam sensors and did no start either, I tried some starting fluid and it started while blocking the air intake hose prior to the air mass sensor, it stayed on for 15 minutes, then it stalled and hasnt started since. Is there a way to test the power stages? Thanks

Could it be that the little rubber hose that connects the idle motor to the intake is missing or just not fully on? Using starting fluid I imagine richens the fuel mix, closing off some of the intake might help get the air/fuel balance right. I have had that little hose blow off from a back fire and then it would only start with gas pedal part way down.

Is that little hose correctly positioned?

DanR '94 964 332,000 miles (98,000 on the new engine)

Finally, after almost a year the 960 is back. It all resumed as "I had a bad mechanic all this time." I asked him what computer or system was he using to make all this tests, he replied that he had another Volvo in his garage and was exchanging parts from the other car to mine and none of the parts he exchanged made the car start. Well when I went there to check, I found out that he was using the parts from a 940. I took the car to a mechanic that has a nice computer and voila!, he had to replace the crank sensor, Cam sensor, oxigen sensor and the coolant temp sensor and the power stages again. the car is runnig smooth. Thanks for your help and I hope this helps somebody else in the forum.