'96 900S Won't Start

[HoundGirl70]

We have a '96 900S 2.3. Got in it one morning and turned over but wouldn't start. We have replaced the crankshaft position sensor, coil, distributor, cap, rotor bug, plugs and wires. Still nothing. It was running fine the previous day. Is there anything we missed?

[Oscuro]

Have you checked the fuel pump? You should be able to hear it under the rear seats when first turning the key to "ON" -- lift up the rear seat cushions to make it easier to hear.

[HoundGirl70]

Yep, hubby checked it and does not hear the fuel pump. He has checked the manual, which reads that the ECU could also be the problem. How do you rule out pump vs ECU?

[Oscuro]

Pull fuses 4 and 32 from the fuse box at the end of the dash by the driver's door. Run a jumper lead from the top pin of fuse 4 to the bottom pin of fuse 32. This will directly power the fuel pump (fuse 32) from another circuit (fuse 4), which leaves the ECU out of the equation. The fuel pump should run when the jumper is connected. You could also use a multimeter set on a high DC amp range instead of a jumper lead; in this way you can also measure the current draw of the fuel pump.

Fuel pumps are a common failure point after 100k-150k miles, whereas the ECU itself does not usually have any trouble. The brushes in the pump motor will wear out and make intermittent contact with the commutator. The pump motor will work fine most of the time, but if the pump stops in an unlucky spot when you shut off the car, it can be impossible to get it going again.

[George McKinnon]

We have a '96 900S 2.3. Got in it one morning and turned over but wouldn't start. We have replaced the crankshaft position sensor, coil, distributor, cap, rotor bug, plugs and wires. Still nothing. It was running fine the previous day. Is there anything we missed?

I had a similar problem, check the ground wires in the engine compartment. If they are loose, the fuel pump will not engage. I actually replaced my fuel pump, it did not work either, then I found the loose wire.

[bullet]

Had the same problem. One morning it just wouldn't start. I changed the cps sensor, only to find out it was the fuel pump.

[HoundGirl70]

Hey guys, sorry to be slow to respond. My husband changed the fuel pump, still won't start. He also check all relays and still won't start. Will the ground wires in the engine compartment prevent the distributor from getting spark? My car has been down almost a month and I'm getting pretty frustrated ... thanks!!!!

[HoundGirl70]

Husband is still wondering if it could be the ECM????

[Oscuro]

It seems that you have thrown a lot of parts at the car without a real diagnosis. It is not out of the question that some new parts may be bad out-of-the-box. Run some basic tests to get an idea of what is going on before replacing anything else:

• You replaced the fuel pump. Does the fuel pump now run when you turn the key on? If not, does it run when jumpering at the fuse block? If it works there but not at key-on, there could be something with the ECU or ignition switch, relay, etc.
• After cranking, pull a spark plug. Does it smell of gasoline? If so, fuel is reaching the combustion chambers. If not, look closer at the fuel system or controlling circuitry.
• Pull a spark plug and ground the threads with a jumper wire. Crank engine. Does the the plug produce a spark? No spark would point to a bad coil or worn/bad distributor components. Or maybe a bad CPS.
• Is there fuel in the tank?
• Bench test relays for important circuits.
• If spark and fuel pass muster, check compression on each cylinder. But bad compression seems unlikely unless something really bad has happened.