What would cause this?

[MrMarcDude]

Hey guys i was wondering what would cause me to not get power to the fuel pump? This is on a 78 280z... totally stock. I replaced the fuel pump, and still nothing. I'm getting pulse to the injectors, and im getting spark... just no power to the pump. Could it be one of the sensors on the motor?

[EScanlon]

Don't know if the 78 has the inline fuse as the 73 + cars did, but that's one place to start.

The other, is are you sure you have the polarity of the pump connected properly? Check to make sure that, as simple as this sounds, that that isn't the case. Some motors will not accept reversed voltage.

FWIW

E

[MrMarcDude]

yeah I'm sure its not the polarity.. i took off the fuel line while cranking the motor over, and watched the fuel in the line. Didnt budge... before it stopped starting, the motor would sometimes cut out while driving... losing all power. But then would start right back up again. wtf? Its annoying the crap out of me!

[sblake01]

Possibly the ignition relay. It's located in the relay bracket in the passenger side footwell.

[aldersonr]

I ran into the same problem with my 260Z. As a fix and theft detterent I reran a wire with a cutoff switch on the positive side. Just make sure you use the right amp fuse and tap into a source that only has power with the key on in case you forget to turn it off!

[sblake01]

A 260 is set up differently than a 280.

[zpizzaman20]

Grounds Grounds Grounds! They effect these cars in so many ways.

I had a 78 Black Pearl in 1983 that would not start. Got out the Factory Service Manual and ran through all the stuff. Figured out that the fuel pump was not working and did not have a meter (or like to use one). Had it towed to an electrical shop. They charged me for 2 hours labor and it was fixed. Problem they told me: The dome light was grouding to the frame. Have never understood that but I hate electrical.

Funny 'cause I spent all day yesterday wiring an aftermarket stereo into another 78 BP that I have now. Could not get one speaker working, tried everything. Finally took it back out and found the wire had broken at the connection.

I hate electrical!

[LB260Z]

probably a break in the wire somewhere.... or corrosion....??by the way you described the intermittent on again-off again pump while driving sounds like thatis most likely your problem.I believe the wires are in the harness that goes to the taillights. that is where I would start. sometimes things that are not even seemingly related are involved because of the way circuits are wired.check all wires in the cargo area first for any damage, then follow that harness to the fuse block checking all the way up.. not a fun project but you could end up saving$$$$ good luck.

[MrMarcDude]

ok turns out im a moron. When i pulled the wires under the car to connect them to the new pump it ended up pulling the bullet connector under the seat apart. good times! One more question... does anybody know where i can get an aux. air regulator for that? Nobody has em!

[sblake01]

.........One more question... does anybody know where i can get an aux. air regulator for that? Nobody has em!

I have a couple that work. Is your missing or just not working? PM me if you need it. Or if you want a new one try here. I know it's for a BMW but it works. We discussed that here in a thread a couple of years ago.

http://www.bavauto.com/shop.asp

[sblake01]

Addendum to the previous post: Search for part number 0 280 140 124. It's for a 1980-81 BMW 528i. I've had one on my car for years. It works fine.

http://www.bavauto.com/shop.asp

[Rick Bolus]

I think I have a few air flow meters still in some boxes headed to ebay when i get time, let me know if you need one before that.