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Fuel pump runs constant, where to buy fuel pump/efi relay for 1977 Z?


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My fuel pump has been running constant as long as the battery running. It may have been doing this since I bought the car as I noticed my battery was running down when the car was parked last fall when I bought it. I didn't notice the fuel pump running until recently when walking past the car, I heard a hissing sound which I mistook for a leaking tire, but quickly found to be coming from the fuel pressure regulator (much louder than the fuel pump itself). My parking procedure than included pulling the battery terminal every time I shut the car off.

 

Anyways without attempting to troubleshoot, I ordered a new fuel pump relay, not being able to think of anything else that could cause the issue. Anyways the relay showed up yesterday, and after searching for it's location I found it above the ECU under dash, but of course the one I pulled out was nothing like the one I just acquired, it had 2 plugs into it, and I believe it's the combination fuel pump and EFI relay I've heard mention of. The FSM had instructions on how to test the relay (matching the relay I removed, not the new one), and sure enough I wasn't getting a click and it failed one of the continuity tests. Since it was presumably stuck in the closed position, i decided to give it a couple smacks and sure enough it then tested good. I reinstalled it and now the fuel pump is shutting off, so I've stopped pulling the terminal. I'm still a bit nervous about it sticking again, so I'd like to replace it for peace of mind, however I'm unable to locate another.

 

Does anyone have a source for a new one? The only ones I can find are the same as the wrong one that already showed up to my door.

 

 

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I had the same issue and this is how I fixed it. The main power feed for the fuel pump has a connection just behind the passenger seat. I unplugged this and ran my own power lines from that connection to a bosch relay under the dash. I then used the original signal and power connections to the new relay. You can use spade connectors in the original wire harness plug so to keep the harness intact. This took me about 30 min and has lasted 7+ years with no issue. I also installed a blade type fuse to the power supply at the relay for extra insurance...

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Head to the junkyard. I've got a good 20-30 relays that I've pulled from relay boxes in anything from Fords to Daewoos, they tend to use the same size blades. Got all of 'em in one day for $20. I promise you, that's a good $400 of relays if you bought 'em online new. It's just an electronically operated switch controlled by the ecu in this application. 

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Head to the junkyard. I've got a good 20-30 relays that I've pulled from relay boxes in anything from Fords to Daewoos, they tend to use the same size blades. Got all of 'em in one day for $20. I promise you, that's a good $400 of relays if you bought 'em online new. It's just an electronically operated switch controlled by the ecu in this application. 

 

 

I would have thought the 10 or 12 blade relay I'm referring to is pretty specific to the car. Unfortunately I live on an island where the chances of a Z popping up at the junkyard are pretty much 0. So far the "give it a smack and reinstall" fix has worked, of course it's probably bound to stick again, but I figure that's when splurge for the new one, unless I can find a cheaper source.

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My 78z has a five blade relay for the fuel pump. You might have the ten blade relay that also contains the EFI relay. IIRC it's just two relays in the same housing. So two five blade relays will do the trick. Actually, since the relays are set up to be used as normally open, you could just get two normally open 4 blade relays and wire them in, but in the end it's no different.. The FSM or a good wiring diagram will tell you what wires to go where, but the harness might be designed so any Nissan 5 blade will fit and operate without modification. 

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You can uncrimp the sides of the metal cover and take it off.  Look inside and see why it's getting stuck.  It has eleven blades so it's not so simple to replace with one or two common relays. 

 

 

Added a drawing to show the complexity.  From the 1976 FSM.  Doesn't look like fun, although it could be figured out.

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post-8864-0-81472900-1370973904_thumb.jpg

Edited by NewZed
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m1ghtymaxxx :

 

I'm sure I have that relay spare, maybe two. Nothing fun about replacing THAT with regular relays.

 

I think I can beat the $115 MSA pricing. Hows $114.95!  No?  okay, $5.  + postage. Its a long way to there.

 

Drop me a note z240@shaw.ca and we'll get this going. Gotta take care of my brother-on-the-rock!

Edited by z240
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m1ghtymaxxx :

 

I'm sure I have that relay spare, maybe two. Nothing fun about replacing THAT with regular relays.

 

I think I can beat the $115 MSA pricing. Hows $114.95!  No?  okay, $5.  + postage. Its a long way to there.

 

Drop me a note z240@shaw.ca and we'll get this going. Gotta take care of my brother-on-the-rock!

 

 

Thanks a ton! You have mail

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It sounds like you have this covered.  I went through this two years ago and bought

the new one figuring if the original lasted 35 years the new one was worth it.  Last

year I did the hybridz thing and now the relay sits in a drawer.  If z240 is not able to

help drop me a PM.

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we've got a lot of guys on here parting out S30's so if anything post up a request in the Wanted section.  As for the good whap and reinstall fix. That's probably all you need unless it's corroded inside. there's not that much that could go wrong in a relay so you're probably good.

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