10 replies to this topic

[halw55]

While driving the car, it just quit. It turns over alright but the fuel pump is not running and there is no spark at the plugs. I have 12v at the fuel pump relay on both legs. The coil side & the run to the pump but the relay does not click. I checked the main relay in the engine compartment by unplugging it with power on and it clicks as I unplug & plug it in. Have tried a new ECU with no change. If I jumper across the relay for the fuel pump, the pump runs. I have checked ECU fuse in engine bay and HOME fuse under the dash all good. I am Lost at this point. Can the Cam or Crank position sensor have any effect on both systems? The timing belt is only 6 mo. old.  ??

[Ron Alan]

There is a relay under the dash that is part of the fuel(ignition?) system. Also the main fuel relay in the box on the passenger wheel well.

 

Helped a friend with the exact same problem...no fuel pressure (and spark it would seem). The relays tested fine but the path between them was broken?? Basically seemed to be in the wiring harness/plug ends. I wish i could explain this better or REALLY new what fixed it but we bipassed something in the harness with a new wire and it fired up. Another person who could read the factory wiring diagram diagnosed this and told my friend what to try. Not sure if this helps but its what i remember...not an EE or much of a mechanic for that matter  

[DrDomm]

I had a similar situation that was a "short" in the fuel injector harness.  Swapped that and it worked.  Just a thought.

[BustedKnuckle]

Failed crankshaft position sensor will kill injector pulse as well as signal to the coil packs. Check injector pulse w a noid light (admittedly no easy to get to) easiest way to check a crank sensor is to hook up a scanner and monitor RPM pid while cranking the engine. If the value is zero rather than around 200 rpm that's your issue. I unplug the crank sensor for this reason to prime the engine with oil pressure before starting a new motor or engine that has not run for awhile.
-R

[BustedKnuckle]

You can also check the fuel pump relay by grounding the pump terminal in the under hood DLC. The ground wire that closes the relay (Light green and some other color I believe) splices to the terminal in the DLC allowing manual operation of the pump

[BustedKnuckle]

You can also check the fuel pump relay by grounding the pump terminal in the under hood DLC. The ground wire that closes the relay (Light green and some other color I believe) splices to the terminal in the DLC allowing manual operation of the pump

[BustedKnuckle]

You can also check the fuel pump relay by grounding the pump terminal in the under hood DLC. The ground wire that closes the relay (Light green and some other color I believe) splices to the terminal in the DLC allowing manual operation of the pump

[halw55]

If I jumper the fuel pump to ground in the diagnostic port in the engine compartment, the fuel pump works but still no spark on any plugs. Could either the crank or cam position sensor cause this? All fuses & relays have been tested and the ECU has been changed. There is 12v at pin 1A of plug F to the ECU. Have not checked to see if the injectors are pulsing when cranking the engine. ??

[Bench Racer]

halw55, observed your from Memphis, TN. Jim Drago, owner of East Street Salvage and owner of this site is from Memphis. Approach Jim face to face as a mentor to find the root cause of your issue. He has built and sold a gazillion 1999 Spec Miatas.

 

It's ok Jim, it's winter time.

[Mark]

Try replacing the fuel injection relay located in the fuse box under the hood. I always keep a spare or two of these in the trailer as they seem to fail often.

[halw55]

Found bad crank position sensor as the cause to everything. r&r'd said sensor and all is fine finally.

Thanks for all the information.