A big Howdy from North Texas! I am new to this forum but not too new to the z cars. I just purchased my brother's 79 280zx. Between the both of us we have changed the computer, injectors, fuel pump, and fuel filter. What is it that actually tells the fuel pump to come on or to advance the fuel when you first turn the key on. Its very hard to start. Takes a long time to get pumped up. I cant hear the pump humming when i first turn the key on. I know these cars can be an electrical nightmare, because Ive owned one before. Any help would be greatly appreciated. Im to the point of putting a 350 chevy in it, but I would rather stay with the original engine. Thanks a lot.

Chuck

 

Welcome to ZDriver!

So you are saying that it eventually starts after a lot of cranking? If the pump wasn't pumping, it wouldn't ever start.

Have you checked the fuel pressure?
Have you checked the fuel pressure regulator?
Have you checked the fuel pump relay?
Have you checked for proper spark?

 

Its like first thing in the morning. or after it cools down. When you first hit the starter it barely starts for a second. If you keep hitting the starter it will get better and better until it finally starts. When it does start, it back fires when you give it the gas. Then it clears out and accelerates. Runs very rich when it finally starts.

 

#1: Check your fuel pressure (before starting it when cold). The fuel pressure regulator may be leaking down, which would mean the fuel pump has to re-pressurize the lines before it will start.

#2: Check the AFM, CHTS, & TPS connections for looseness or corrosion. You should probably also open up the AFM and tune it ( see: https://www.zdriver.com/forums/240z-280zxt-s30-s130-tech-tips-275/js-how-rebuild-your-afm-15277/ )

 

Thank you. I will try these out. What if the fuel pump isnt giving it the initial prime when you first turn the key on? And where is the CHTS located?

 

Check the fuel pump relay & ignition switch / wiring.

It's located on the right side of the head between spark plug 5 & 6.... but since yours is a 79, it's most likely in the thermostat housing.

 

ok i remember a sensor being in the thermostat housing. I will check that. There's a little black box by the battery that Ive been having some problems with. Any thing there that would affect the fuel pump? Its the little one with all the little looped wires.

 

< Adam Sandler voice from "The Wedding Singer" > Once again, things that could've been brought to my attention YESTERDAY!

Those are called Fusible Links. What kind of "problems" are you having with that black box?

Minor details....

 

seems like the wires have a loose connection and someone has a regular wire coming out of it to the positive side of the battery. Every once in a while it wont turn over and I have to go jiggle that wire at the battery.Then it will start. I just bought new cables and ends. Im about to clean every electrical connection I can find and I am praying that it fixes my problem. Im thinking maybe more ground cables couldn't hurt either.