Jason280ZX

Hey guys, so im gonna need some advise on why some things happen when I installed a toggle switch to a 79 280zx. I personally own an 83 model but im working on my brothers 79. So because im making a toggle for the FP is because lately the car has been having a hard time to stay on and even idle very rough but manages to stay on. Before all this, the car would run very fine, and at the time being I was trying to adjust the distributor timing and I had the distributor turned all the way completely to the right when facing the intake side of the engine. The engine would idle very high of doing so. The adjustment is another issue to explain later. When I press the accelerator pedal down just enough to reach 1000rpms, it'll stay on, but when I give it more. It drops very quick, enough to die. From what I know about this year model is that it comes with a dual relay system to allow the FP to actuate. Im very understandable with my 83 wiring for the fuel system that when I made my own toggle switch, the wiring diagram was simple enough to understand that no problems will occur if I did so. My 83 runs fine and everything, but that's because of the simple 1 relay set up. From what Ive been testing, the car is receiving strong spark from the spark plugs. The fuel injectors fire. I checked the FP relays #1, passed all test, but #2 didn't. I wasnt too sure if the relay can be causing why the car was acting the way it was. I also check the EFI relay and it was fine also. So for awhile ive was in a loop of confusion. Then just recently when I was running the car. I removed the #2 relay. The engine just shot up idling high again like before, but due to the non adjusted distributor. Now thinking I found the problem , I looked back at the wiring diagram of the fuel system and apparently if the #2 FP relay were to fail, it will cause the FP not to operate. Relay #2 is also linked with the alternator and fuel pressure switch. So whats been happening is when I turn the car over with the new toggle switch directly connected to the FP. The engine turns over but doesn't turn on. After leaving the FP on for a bit; I shut it off and crank it over again, then it starts up strong, BUT THE FUEL PUMP ISNT OPERATING! I know the engine can remain on for a while without the fuel pump on but just enough fuel pressure to keep the fuel injectors supplied with fuel to fire. Knowing that makes me want to keep the FP on the whole time, but when I turn it on as the engine is running. It idles down to near stalling. So whats happening? I need someone with 79 model experience who might have done the same with making a toggle switch for the FP. Or some sort help who might have an idea what can it be. Suggestions? Sorry for the long explaination but I want to specify everything that's happening.

ZXR616

I've got a 79 280ZX that was loosing fuel pressure after sitting for a short period...the check valve at the fuel pump obviously not working. This made restart harder. The 79's do NOT turn the FP on until there is oil pressure or the alternator shows the engine is turning. Rather than replace the check valve, I decided to have a "cool" red toggle to turn on the FP after key on. Wiring is easy...wire the switch in line with the BROWN wire going to the oil pressure switch/sender on the right side of the engine. This allows turning on the FP before cranking, allowing the fuel rail to pressurize, making starting easier.

The rough idle etc. may be a result of a vacuum leak or a thermodine problem.

Jason280ZX

Thanks for the advise! It really helped!

FricFrac

Fix the problem instead of working around it. If the oil presure switch isn't working replace it.

XenonS130 and get the FSM - it will guide you through 99% of the problems you'll run up against.