electrial assistance needed

[Chase 3]

I have a '78 280Z all original. Sometimes it will not stay running. It sounds like it is running out of gas but it is not. The engine will attempt to start and rev up and down then just die. When this condition happens the red alternator light comes on at the gauge. I changed the alternator and that helped.

If I add a battery charge the car will stay running. The parts store states both the alternator and battery are fine. I have cleaned all light bulbs and sockets, electrial grounds to the engine and chassie, changed all fuseiable link connectors and wires. Simply running out of areas to investigate. Like I mentioned, this comes and goes. Any help will be greatly appriciated. Chase 3

[beandip]

I want to welcome you to the Club. Frankly I cannot remember if your '78 had a internal regulated Alternator or if it has a Regulator on the inside fender. You said that the engine will continue to run if the battery is charged. Does it go dead or become discharged? If you check the voltage in the Battery with the engine running and then with it off, you should be reading about 13 v+ with it running. If not and you have a side mounted regulator , be suspicious of the regulator. Have you or anyone altered the wiring or has there been any damage to the wiring harness? Thinking a bad splice or broken wire. Some one else will jump in here with more info. You came to the right place. Gary

[sblake01]

78 is the one and only S30 that came from the factory with an internally regulated alternator.

[280~Master]

Have you checked the fuel presure. I have heard of the fuel presure regulator causing problems like this.

[TomoHawk]

When was the last time the fuel filter was changed?

[Chase 3]

Have not inspected or changed the fuel filter or reviewed the fuel pressue. Interesting that fuel pressure and filters are mentioned. The first 2 times this happened was at the gas station after I filled the tank with fuel. Kind of like it could not pick up the fuel and deliver it to the engine. I will check these out this weekend. Thanks for this direction. Mike

[280~Master]

Could also be a bad tank. When you fill up it slushes all the crap at the bottom of the tank around and this could cause clogging of the pick up line.

[Chase 3]

Wonerful!!!! If memory serves we right is there not a little ticking sound when you turn the ignition on? Do not here this anymore? I am beginning to question the fuel pump or electrical system for the fuel pump. I will investigate this weekend.

Thanks

[Chase 3]

Problem corrected...There was no voltage going to fuel pump....Applied 12v direct and the pump functioned....there are 2 relays on the driver side fender under a large metal cover, they control the fuel pump...One appears to trun the other on...Clean both relay's contact points...reinstalled them on the car, turn the key and the car started....I have one replacement relayson order but will have to go to Nissan to get the other one.

Car actually stopped one time after I cleaned the relay contacts...I tapped/bumped the relay cover and the car started.... I have driven for 3 more days without any issues....Enough confirmation for me that the issue is electrical machinical failures of these relays.

Thanks for all the assistance.

[sblake01]

You know, I've went through that exact same thing myself when I bought my 78 in 1997. Including having to bump the fuel pump control relay (the larger of the two-#1 in the pic) to get the car started again. I would bet that that's the only one that's bad. I didn't change the smaller one (#2) and the car has been fine ever since. It's been so long the I had forgotten that episode.

[full house]

maybe your out of fuel or its been stock!

[sblake01]

Ah, wwwwhhhhhaaaatttt????