no spark

[autocross97]

the engine will crank but will not start. i am not getting spark from the coil and the fuel pump relay will not turn on. both the coil and the relay have power but are not being grounded by the dme. the dme is getting power on pins 37 and 18 i have good grounds on pins 2 14 19 and 24. i have checked the cps and it measures 550 ohms, it is plugged into the correct connector on the harness, i even tried to swap the tack connector and the cps connectors to make sure they were plugged into the right connectors. what else could be causing this?

[billybobjoseph]

Check the fusible link on the smaller of the two positive battery leads. It's about a foot from the battery under the carpeting in the trunk. Looks like a flat spot have to peel back the rubber to check if it's blown or not.

[autocross97]

its got power from the main relay to to the dme on pin 37 which is fed by the wire with the fuse link right?

[jlevie]

If the DME has power when the ignition switch is on, the fusible link is good. A static check at the main relay socket won't necessarily reveal a bad fusible link. The link can be corroded and thus present a high resistance path. So you need to check voltage from the fusible link under load. With the ignition switch on and the DME powered up, check the voltage at the power point where the small wire from the battery terminates.

After verifying the integrity of the CPS circuit at the DME connector, I would try a different CPS and then a different DME in this case.

[billybobjoseph]

You can also test the resistance of the link directly with an ohm meter and back probes. Disconnect the ground then the positive battery cables and test the resistance across the link.