280z starts and then dies a few minutes later

[Usain_Boat]

A few months ago I started this thread on this site but had to leave for school and couldn't work on the car. From this point, I have tested a few things and found at least one problem. Previously it was suggested to check the fuel pressure and after the engine dies it is still at 32 psi. Also in the previous post I mentioned the first time the car died like this was on the road after I clutched in, upon looking around the clutch pedal I found this red wire in the ECU loom that was worn away by the pedal. I haven't traced it yet so this could be part of the problem. 

Just to save a click here is the original problem post from me : I have a 1978 280z that I've recently put back together after rebuilding the engine, rust work, and paint. I've gotten the car to the point that it has run three times for various lengths of time. The second time running, I timed it and got it as close as possible but ran out of adjustment on the distributor. When it ran this time I had it on for around 25 minutes and with the initial break-in done decided to go for a ride. I made it 1/2 a mile down the road before it died grabbing fourth and wouldn't run afterward. After an emergency tow home, it would briefly fire up for maybe one second and then die. The next afternoon I tested to see if I had fuel flowing to the rail (I haven't tested pressure) and there is definitely fuel flowing while cranking. Knowing this, I tried running it again and it fired right up and idled for about a minute until I pushed the clutch in to back out of the garage where it died and would not restart. At this point, I have done lots of troubleshooting to get it to this point and any help would be greatly appreciated.

[Av8ferg]

I’d do a continuity check with a multi-meter on the wire bundle. If you have one wire that has compromised the insulation there is a good chance you have others that you can’t see. It’s a PITA sometimes to run wire problems because they could have an intermittent connection only manifesting during vibrations or upon heating up. So be patient, try and move the wire bundle while testing and test multiple times and see what you find. Wal280z has a wire diagram he made that’s awesome that your can download that will help you find the end points of each wire you’re chasing.


Sent from my iPhone using Tapatalk

[Zed Head]

1 hour ago, Usain_Boat said:

until I pushed the clutch in to back out of the garage where it died and would not restart.

 

 

Looks like you created a short circuit.  Check your fusible links.  Hopefully they did what they're supposed to do.  The wire is still red instead of charred so the odds are good.

[siteunseen]

4 hours ago, Av8ferg said:

 Wal280z has a wire diagram he made that’s awesome that your can download that will help you find the end points of each wire you’re chasing.

Yes!  It's very nice...

 

[Usain_Boat]

4 hours ago, Zed Head said:

 

Looks like you created a short circuit.  Check your fusible links.  Hopefully they did what they're supposed to do.  The wire is still red instead of charred so the odds are good.

Well I cranked it today and it ran for 45 minutes including driving it around my neighborhood. I'm really confused now

[wal280z]

4 hours ago, Av8ferg said:

Wal280z has a wire diagram he made that’s awesome that your can download that will help you find the end points of each wire you’re chasing.

Yes, but the OP has a 1978. Use of this diagram for your car may help, but it also may have you chase circuits that were modified for the 1978 model. Just saying.

Each one of the 280 models had their own unique diagram, specific to THAT YEAR OF PRODUCTION. That being said, there may be some overlap between the end of model year and beginning of model years.

@Av8ferg & @siteunseen, thank you very much for the kudo's. Hard to believe that diagram is coming up on it's 15 year anniversary... Where did all the time go?

Wayne