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No voltage to fuel pump

Old 07-05-2005, 10:21 AM
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No voltage to fuel pump

Newbie here, I have a 1978 280Z that sat for several years before I purchased this car in May. I drained and cleaned the fuel tank, replaced the fuel pump and the car fired right up and drove with no problems. I haven't driven the car much after this, however.

My problems began as I replaced the starter, which was acting up occasionally. As I reattached the battery cables I accidentally shorted the cables and got a small arch to the frame, but only momentarily. As I attempted to start the car I noticed the pump didn't seem to prime and the car would not start. I did a voltage check at the fuel pump terminals- no voltage. The strange thing here was that I could not get the pump to run when applying 12V directly. pulling the pump, It was not working and was shorting badly when applying voltage- and I replaced it.

I checked all of the relays (fuel pump, fuel pump control, etc.) and the fusible links, all are functioning. I also did a continuity check on the control unit and everything checked out OK. I have a factory service manual and did these checks per the manual. any other suggestions? Hope I didn't fry anything too bad, but who knows. Any help would be appreciated. The pump works now when applying 12V, but should as it is new! Thanks!
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Old 07-05-2005, 01:54 PM
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Since you fried the fuel pump you must have fried the fuel pump relay. Try bypassing it to see. Also, can you hot wire the pump while it is installed? Some one had this same problem but the post was in the ZX forum just a few months ago.
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Old 07-05-2005, 03:03 PM
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Originally Posted by theramz
Since you fried the fuel pump you must have fried the fuel pump relay. Try bypassing it to see. Also, can you hot wire the pump while it is installed? Some one had this same problem but the post was in the ZX forum just a few months ago.
When wiring the pump directly to a 12V source, the pump works and the car will run.....The relay acts normally-- that is it gets continuity only when applying voltage to the (2) terminals 90 and 91 per the shop manual. You are saying the relay can still be bad, even when acting"normal" so to speak? Excuse my ignorance, I'm new to thes Z cars- but I love them!
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Old 07-05-2005, 04:31 PM
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No, a relay is only a switch. But it must have the right voltage in and out so check the volts out also. If the points are bad, it can still pass a continuity check. Be absolutely sure you are checking the right relay.
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