Now what? Need advice...

Crazy Horse · 10:39 AM

I have an 83 944 NA with 30,000 orig miles. Drove the car from S. Florida and another 2,00 miles and ran perfect.

I decided to install a 6-blade fan in place of the 3-blade A/C fan. Fan works well and even turns the right direction. Guessed right the first time.

Went to start the car and she just rolls over - no catching at all.

I checked fuel pump fuse and is in great shape. I have over 12 volts to the coil when the ignition is turned on.

Anything that I could have easily messed up? Car does have an alarm, but has not been an issue.

I find it hard to believe the coincidence of me doing the fan switch AND it suddenly developing a starting problem. I have a battery disconnect and did disconnect the battery before I worked on the fan. All is back tight now and have plenty of juice.

Any ideas right off the bat?

Any assistance would be greatly appreciated.

Slam · 07-02-2009, 11:39 AM

Did you unplug any sensors when you did the work?

Crazy Horse · 12:16 PM

Slam,

Thanks for replying. I checked the temp sensor, fan switch and oil sonsor - all seem fine.

Slam · 07-02-2009, 01:10 PM

Coil wire?

Usually the first thing guys here will ask is whether or not your tach bounces while you're cranking the motor.

Crazy Horse · 07-02-2009, 01:45 PM

I have 12 volts to the coil (green wire) when ignition is on.

I was concerned as I was looking for bounce and saw NONE at all on the tach while cranking.

Crazy Horse · 07-02-2009, 02:49 PM

Had to wait until my son got home to crank while I watched.

-Suddenly I have no spark at the plug. I checked the neg wire and to the block - all clean.

Is it possible I arced something (DME relay, etc...) when I disconnected and reconnected my battery?

Slam · 07-02-2009, 02:56 PM

Hmmm. Do a search here and read up on speed/reference sensors and changing your ignition switch.

My car did what you're describing and I ended up swapping out the ignition switch.

Good luck!

nynor · 07-02-2009, 03:08 PM

check the connections where the sensors plug into the wiring harness, top center behind the engine.

Razorback1980 · Razorback1980's Garage

Slam definitely knows the early years well but if the tach doesn't bounce, I would look to nynor's suggestion first. There is a checklist to follow if you have no spark. With you having 12V to the coil, I wouldn't think the ignition switch was the problem unless you DON'T have 12V during cranking which is possible.

Here is a short test to help determine the problem...courtesy of SoCal Driver.

Check for power at the coil and at the injectors with the key on.

No power at the coil it's the ignition switch or related wiring.

No power at the injectors it's the DME relay. Sometimes the wiring harness breaks and you won't have power to all injectors so test all of them. You can wire around the DME relay but making a "Y" wire and jump across terminals 87 and 87b and then plug it into terminal 30 last.

Power at the coil and injectors points to a bad reference sensor. The connector may be corroded and/or not plugged in all the way or cracked and may have broken the wires inside. Check for tach bouncing here as well.

No spark can also be the HV wire from the coil to the dist cap. Can also be a loose or broken rotor. Can be a broken timing belt not turning the rotor. Take the cap off and make sure it's turning. Usually if it's the timing belt you bent a valve and the motor will spin very fast. The ignition switch is also a suspect here as it could provide power to the coil in the on position but not in the start. Clip a test light on the coil and see if it has power while key is in the start position.

In most no start cases it's not the coil or the wires or the dist cap or the rotor. Usually the DME relay, ignition switch, reference sensor(s), broken timing belt then fuel pump. The DME is way down the list.

With the key on check for voltage at the coil and at one of the injector plugs.

No voltage at the coil means the ignition switch is suspect/bad. Could be the connector at the back of the ignition switch too.

No voltage at the injector plug (pull one to check) but at the coil means the DME relay is suspect/bad.

Voltage at both means the reference sensor is suspect. Test for spark by pulling the number one spark plug wire, inserting a spare plug, lay it on the intake to ground it in a possition you can see when you crank the car. If you don't have spark check the sensor connectors as described earlier. Could also be an out of adjustment sensor.

No spark can also be the HV wire from the coil to the dist cap. Can also be a broken or loose rotor. Can be a broken timing belt that will not turn the rotor. The ignition switch could be making the circuit to the coil when in the on possition but not in the start posstion. Use a test light with aligator clips on the power side of the coil to see that voltage is there during cranking.

Since you checked for voltage at the DME connector it is to be assumed that the first set of contacts in the DME relay are working. These power the injectors and the DME.

The fuel pump runs only when the engine is cranking. You can hear it if you lean out and down of the car while cranking. It will run for a half second or so after you stop cranking.

You can bypass the DME/fuel pump relay with a simple aligator tip jumper between aux fuse #2 and #3. This will run the fuel pump. Used to check fuel pressure and flow at the rail with out running the engine.

In most no start cases it's not the coil or the wires or the dist cap or the rotor. Usually the DME relay, ignition switch, reference sensor(s), broken timing belt then fuel pump. The DME is way down the list.
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