Does the 280zx hold pressure all the time ??

[Pacey]

Hi all and HAPPY EASTER more time to work on the Z

 

I have a L28 EFI

Lately I have noticed that the fuel pressure drops to zero overnight.

I have a pressure gauge next to the pressure regulator, when I start it up the gauge jumps straight to 38psi no problem. At idle she sits at approx 34psi, when I rev it goes upto 37psi.

If I disconnect the vacuum on the regulator it jumps to 37psi.

 

Could I have faulty regulator, a leak somewhere ( that I haven't found yet) or a sus injector or two.

Car runs really well, no issues.

 

Not sure if the lines hold pressure all the time or not

 

Thanks

 

[luvemfast]

So are you saying that you're losing pressure overnight while the car is sitting there in the drive doing nothing?

I woulud expect that to be normal, but I'm no expert.

[Pacey]

Thanks Simon

Yeah it happens while doing nothing overnight.

And I've never noticed this before,

The reason I'm probably asking is that, I went to the wreckers on the weekend and pulled off a pressure regulator from another Z, this car had probably been sitting there for months or years.

When I took it off it still had heaps off pressure behind it.

Which makes me think I have a problem somewhere..

[Zedman240®]

That is what is supposed to happen; the fuel that's pressurised does go back through the fuel return back to the tank and pressure goes to zero. It's behaving as it should. Reason the vac line is attatched to the regulator is that during idling, the engine doesn't need so much fuel so the reg backs off the fuel pressure a tad. Less fuel pressure, less fuel and vice-versa. When there is little to no pressure, the reg gives full fuel pressure meaning more fuel to the injectors.

[.]

I have bought a wreck that I assume had not been driven in months or even years, yet when I cut the fuel lines fuel still spurted out. I think what is happening is the pressure drops to 0 while the pump is not engaged so long as the ambient temp is low (ie over night). But I think rising ambient temps are enough to cause a spurt and it might not be enough pressure to register on a gauge. The bottom line is don't panic. If you haven't got leaking fuel or fuel odors around the engine bay don't go looking for a problem because you are just as likely to cause new ones.

[Pacey]

Thanks guys

appreciate all the feedback.

Thought everything was ok, as the car is running really well, just couldnt really understand why the pressure would drop if it had no where to go.

like i said, it was something that i hadnt noticed before, see what happens when you add things to the engine that show you what it is doing (pressure gauge)

Btw

have a look at my post about the larger AFM for the 280z, i was very excited that it worked out the way it did.

i will post photos as soon as i work out how to..

 

have a great Easter..

[Gordon Dobie]

You say your car is running fine. That makes you a lot better off than some vizcar members.

Life's to short to look for problems. Remember the old maxim " If it ain't broke don't fix it"

 

Cheers

 

Gordon Dobie