Jump to content
HybridZ
SoFlaZ06

cranks, but no start/ignition (video)

Recommended Posts

SoFlaZ06    0
 

I have a 1978 280Z, I'm new to the Z and this platform and looking to see what direction to start diagnosing this.

 

So i'm driving one day, and car  just dies. It will turn the engine over, but won't start. it appears everything electrical if off when the key in in the "On" position. then I noticed the switch is working funky, but I haven't had the car long enough to confirm is this is abnormal. but i appears to be working backwards, like everything (gauges,fuel pump etc) turns on when key in the "Acc" position, but turn off when in "ON"

 


 

So I figure the switch is bad and wanted new keys anyway, ordered new ignition, same problem

 


 

Where do I go from here? where can I get schematics for these cars

I tried manually engaging the starter, with the key in the "acc" position, to see if it'll run since the fuel pump etc is running, but that didn't work :cry

Share this post


Link to post
Share on other sites
NewZed    56

You can get service manuals with schematics at nicoclub.com.  Link below.

 

1978 has an odd fuel pump power circuit, with multiple relays.  It's shown in the Engine Fuel chapter.  The pump should get power at Start, and when the engine is running, but not at Run if the engine is not running.  But your problem, since things seemed to work right, might be related to the Ignition Relay.  A short maybe.  It's schematic is shown in the Body Electrical chapter, with location, and in Engine Electrical too.

 

Could also be that somebody mucked around with the wiring and it has failed.  I'd figure out why Acc is powering the pump first, then figure out why Start is not.  

 

Good luck.

 

http://www.nicoclub.com/FSM/280z/

Share this post


Link to post
Share on other sites
Pharaohabq    13

I think Globerunner513 is onto it.  That's the first thing I'd have checked.  Most of the systems run through those fusible links.  When I've blown one it was like a complete systems failure.  No starty, headlights acted funny.  all the fuses were still good, but the fusible links burn slowly so momentary high amp draws will heat, but not burn one. A little longer draws will burn it.  I'd check those and then keep looking.

Share this post


Link to post
Share on other sites
SoFlaZ06    0
ok so I have spark, I can prime the fuel system in the accessory position, the fuel pressure gauge will peak at 36psi, sometimes it'll hold it during cranking, sometimes it won't, I'm not sure how the fuel relief is setup on these cars. but the fuel pump definitely isn't running on the "on" or "start" position. 

 


 

So I went back to the ignition switch, I have constant 12.5v from the White/red wire, in the ignition Acc position, i'm getting 12,5v there too, that's the blue/red wire, in the ON position, I'm getting the 12.5V there also. from the switch to the fuse box, and leaving the fuse box. 

During starting phase, the black/yellow wire is reading 12.5V also. So assuming the wiring isn't mixed matched. the ignition switch checks out as functional. The schematic I have doesn't identify the colors.

 

No i'm trying to figure out which is the Fuel pump control relay and which is the fuel pump relay, so i can start testing there. I see 4 relays on that bracket

 

Which is which?

 

36790169611_d519b6f023_b.jpg

 

36095748184_b05e9ed369_b.jpg

 

and here's my schematic sheet i'm working with

 

36533916750_7d278ef42f_b.jpg

 

36930004785_ae2b844a13_b.jpg

Share this post


Link to post
Share on other sites
NewZed    56
Posted (edited)

Nissan's FSM's grow from simple to complex.  The farther you go the more they tell you.  EF-41 shows where the relays are.  And. of course, the next page from your schematic shows the test procedure.

 

Edit - the relays are in the engine bay, by the battery.  Nissan's pictures aren't the clearest.

post-8864-0-55237200-1504148275_thumb.png

Edited by NewZed

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×