78 280z idle problem

[Jack Pearcy]

Another thing to note is that I went under the car and checked the fuel pump while the car was running with the switch in the off position, and the pump didn't appear to be running. It was making no sound and when I grabbed it to feel if it was running I felt no vibration or hum other than that of the engine. This was also only a one time deal, every other time I would turn the fuel pump relay off with the engine running the car would die from fuel starvation. Still no idea how this happened but I don't think it was from a swelling fuel line. All of the fuel lines were rotted when I bought the car so I replaced all of them along with the fuel filter in the engine bay.

[Jack Pearcy]

Actually come to think of it this wasn't a stand alone event, when I first got my car moving under it's own power I had vitually no understanding of how the wiring worked and so I bypassed the fuel pump relay with a fuse to prime the engine, took out the fuse stopping the fuel pump and drove the car exactly 3.6 miles before the engine died of fuel starvation. The only issue I had the whole way was if I took it above 4k rpm the engine would start to die out. Eventually I came to a stop sign and made a turn and for whatever reason the car stalled and continued to do so no matter how high I reved the engine up or how slowly I let off the clutch.

[jonbill]

My car's a 280z, so it has EFI instead of carbs

Yeah, I saw that. I mentioned carbs because they have their own local reservoirs and will continue to work until the reservoirs empty. EFI only has residual pressure in the fuel supply line which isn't going to give as much as carbs.

[siteunseen]

Efi fuel filters hold about a quart. 

[Dave WM]

3 hours ago, siteunseen said:

Efi fuel filters hold about a quart. 

yes but they use fuel pressure to atomize the fuel, no pressure no fuel for EFI.

[Dave WM]

I think its safe to say the running/non running fuel pump is a rabbit hole not needed to go down. OP did you check the CTS (coolant temp sensor) per the FSM? do the check at the ECU connector.

[chaseincats]

Here's a nice unsafe way to determine if fuel is somehow being pumped into the engine without your knowledge: unplug the fuel hose between the hardline and engine bay fuel filter, put it in a bucket, and have someone try and start the car (with the fuel pump switch off) and see if you get gas.  You'll know real quick if theres some hidden pump somewhere (or if your switch isn't working/wired correctly)...

[Jack Pearcy]

5 hours ago, chaseincats said:

Here's a nice unsafe way to determine if fuel is somehow being pumped into the engine without your knowledge: unplug the fuel hose between the hardline and engine bay fuel filter, put it in a bucket, and have someone try and start the car (with the fuel pump switch off) and see if you get gas.  You'll know real quick if theres some hidden pump somewhere (or if your switch isn't working/wired correctly)...

Well at least I’d know lol

[chaseincats]

Any luck finding the issue?

[Jack Pearcy]

On 6/24/2019 at 7:46 PM, chaseincats said:

Any luck finding the issue?

No, I haven’t had the chance to mess with it anymore I’ve been pulling doubles everyday in addition to replacing the clutch and flywheel, hopefully I can figure it out today. Now I’ve got another issue as the clutch grinds going into gear even though it’s brand new 

[chaseincats]

55 minutes ago, Jack Pearcy said:

No, I haven’t had the chance to mess with it anymore I’ve been pulling doubles everyday in addition to replacing the clutch and flywheel, hopefully I can figure it out today. Now I’ve got another issue as the clutch grinds going into gear even though it’s brand new 

If you installed a new clutch master cylinder you need to swap the pusher rod (the metal bit that goes into the cylinder) because the reproductions are shorter for some reason (this was my problem).  Also be sure its fully bled.

[Jack Pearcy]

I do have a new master cylinder, but I installed it a while ago, it may need to be bled again, as far as the pushrod goes do you mean use the original push rod? I still have it so it shouldn’t be an issue but right now it has the reproduction push rod in it