Hello all I have a 1983 280zx na that sat for a while and in February I went to get it going again. It started but didn't drive for crap went through all the diag in the bible and the fsm concluded the fuel pump wasn't up to task, replaced it and all was well. Due to unfortunate circumstances I had to leave it until this Monday and it started right up then immediately started acting up if I rev it to like 3-4k I can get it kinda steady but when I stop it slowly peteres out and wont start up again, then it did it again yesterday same exact thing. Sparks there gets fuel to pressure. The only thing I can find wrong diag wise is on a pressure leak down test, with the pump running it stays at 40 with the car off (can't see pressure gauge from in the car during the 60 seconds of running I get as im by myself) and as soon as pump stops it's drops to 0 within 2-3 seconds I know it's leaking back through the pump and not anything on the fuel rail. Since I know it's gets to correct pressure I can't understand why it won't start back up after the initial crank idk what I'm missing and it's driving me crazy. If the check valve on the pump being bad can actually cause this issue can someone please explain why. This is my first time ever going on a forum of any kind so if I didn't follow a protocol of sorts or I was to long winded I apologize, any help would be greatly appreciated please and thank you

She had problems with the valve and after a bunch of back and forth finally found one on E-bay from somebody like "sam the fuel guy"???

Her's is a '78 280 but it will be the same as far as I know.

Edited April 16Apr 16 by siteunseen

Is the spark strong and blue or weak and orange? I had an ignition module go bad and it showed spark. But the engine would only start with starting fluid.

As far as fuel, the fuel pressure regulators tend to start leaking down if they sit for a long time. The seat n the FPR gets corroded. They will maintain pressure while the pump is running but leak down quickly once it stops. The simple test is to clamp the feed or return lines and see what the pressure does.

Sparks not particularly strong, coil seems to test well, not entirely sure how to check the module. Just finished doing test at the ECU connection via the fsm and about to check fuel. Relay due to a bad air regulator read. Like I said in post I know the fuel pressure is due to check valve on the fuel pump side so I'm not worried about fpr failure

38 minutes ago, SublimeLizard80 said:

Like I said in post I know the fuel pressure is due to check valve on the fuel pump side

You said but you didn't describe.

Try starting fluid. If it starts but runs poorly, it's not fuel pressure.

Fair enough. Not by the car now but tried starter fluid yesterday and it didn't do anything. All the tests at the ECU checked out except the voltage test for the air regulator on pin 21 so I know I probably need to do some harness tracing. Do you know of any tests for the icm? The coil seems fine but I'll probably just buy a new coil since they're not to expensive just to make sure it's not that.

I should have mentioned the distributor itself also. They are known for worn bushings allowing the reluctor wheel to contact the stator ring, breaking things. If it won't start with fluid, it's not going to start with gasoline.

Good old Blue wrote up a thing about them. The magnetic pickup can fail, there's a test for that. The air gap can be off, there's a measurement for that. Described in the Electrical chapter.

https://www.atlanticz.ca/zclub/techtips/distributorrebuild/index.html

Edited April 16Apr 16 by Zed Head

5 minutes ago, Zed Head said:

Good old Blue wrote up a thing about them. The magnetic pickup can fail, there's a test for that. The air gap can be off

😇Good ole Blue! I miss that rascal.

On 4/16/2025 at 11:50 AM, Zed Head said:

I should have mentioned the distributor itself also. They are known for worn bushings allowing the reluctor wheel to contact the stator ring, breaking things. If it won't start with fluid, it's not going to start with gasoline.

Good old Blue wrote up a thing about them. The magnetic pickup can fail, there's a test for that. The air gap can be off, there's a measurement for that. Described in the Electrical chapter.

https://www.atlanticz.ca/zclub/techtips/distributorrebuild/index.html

Good call was finally able to get back to the car, the rotor bushing in the distributor seems shot now, it's just like the picture in the link. Anything I can do to fix that without buying new?

Sorry meant to quote the air gap, link is the refurb it seems so I reckon I'll read threw it and try a repair

ZCarDepot has been good at sourcing parts. He shows a pickup coil for a ZX. The other parts are hard to find though. I've seen the bushings for sale in the past but not recently. Might be simpler to put in a 240Z distributor with a Pertronix conversion. Or a 280Z with an HEI module.

Z Car Depot Inc

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