This question is not for a Miata, but a 1992 Mazda B2200 truck
I am having fuel pump problems, with it working occasionally only. I cut out a panel in the bed to get access to the pump ( EFI ) When I unplug the connector from the pump to the harness, I get 11.85V at the pump wire, but when I re-connect the plug to the pump part, I get no voltage. It simply vanishes.
The pump works when I connect 12V to it and the relay checks out ok.
Any suggestions?
Disconnect the fuel pump and using a pigtail bulb socket and 12v bulb as a tester across the pump socket, see if the bulb will light. Next, find the fuel pump relay, identify the N.O. contact pins, and jumper them to see if the bulb lights up. What is happening is that you are likely using a high impedence input DVM, and reading "stray" 11.85 voltage. If I remember correctly, there is a relay and timer involved. The timer causes the pump to run momentairly when the ignition is turned on, then shut down until the engine is actually running. There may also be an over ride that causes the pump to run during start cranking. A common problem with some of the older mazdas was ignition switch failure. This can be a cause of your problem if the relay coil does not get operating voltage.
Thank you for the info. Will try this on weekend. Meanwhile, I have connected the pump directly through a switch and run the truck that way, but I would like to have the original system back.
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