'78 280z fuel issues- Help? - ZDriver.com

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'78 280z fuel issues- Help?

Old 12-21-2018, 06:55 PM
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'78 280z fuel issues- Help?

Hello all, and happy holiday season! I am a first time Datsun owner, and looking forward to some fun with my new 56k mile survivor. When I acquired the car, it had been sitting for ??? I purchased the car in belief that it was sorted, but within a few test miles I noticed a hiccup (slight miss) ) when I feathered the throttle from acceleration to less than acceleration. I cracked the fuel filter supply line and drained it and it showed a bit of water and some rusty debris, so I worked backwards to the tank. When I dropped the tank.... OMG! Rust galore!! So, acid bath, sealed, and reinstalled. I inspected fuel lines, and blew some compressed air through the fuel lines towards the disconnected fuel filter. So, all the fuel lines were empty when I recommisioned the tank. When I reconnected everything, I turned the key to accessory, thinking the fuel pump needed to prime the system, and turned the car over.... and over.... and over... and she finally fired up. She ran for a bit, then hiccuped, missed, backfired a bit, and died. My first thought was air in the fuel lines, and it would work it's way out, but after starting again... another spit and sputter session, and dead. Lather, rinse, repeat for another few times and it never got any better. SO- being that the fuel filter was so gooked up in the initial session, I have removed all the injectors and sent them for service and they are due back just after Xmas.... My questions are: What am I doing wrong?? I purchased a fuel pressure gauge and want to hook it up on the line prior to the fuel filter to see if the fuel pump is doing what it should... Where else should I be looking?? When purchased, it ran fine for a bit, but the hiccups got progressively worse, with what I thought was a bad fuel supply issue. Any thoughts and courses of action would be MOST welcomed!
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Old 12-23-2018, 06:19 PM
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Good talk

Guess I should look elsewhere for advice.
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Old 12-24-2018, 12:10 PM
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Depending on where you live and how much ethanol is in the pump gas, you might want to think about flushing the lines between the filter and the injectors with clean gas as well. Don't forget about the return line from the pressure regulator back to the tank.

I've got a '76 I bought two years ago and after 12 years sitting with Oregon's version of pump gas in it, still is totally soured. The tank was in the same shape as yours. I'm not planning on turning the key until this summer (the engine is out of it) but have already taken the system apart and run non-ethanol gas back through every line until the stink was gone and the gas came out clear. Do it outside and don't set yourself on fire.

Hopefully the injector service will cure it. Who are you using?

I'll be curious to see what others think. I'm probably gonna have the same starts and fits. I don't think you're doing anything wrong, but maybe need to do more of the same on the rest of the system.
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Old 12-24-2018, 01:49 PM
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One other thing...the Factory Service Manual has a section on trouble diagnoses in the EF chapter (Engine Fuel). If flushing and cleaning the injectors doesn't help, it's might not related to bad gas and you might find something in the FSM that leads you to the solution. The FSM is found here:

https://www.zdriver.com/forums/gener...car-com-29115/
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Old 12-24-2018, 02:00 PM
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Thanks Z Bear, I have a copy of the FSM, and another factory guide to troubleshooting the EFI. I read in the latter that the fuel pump has a difficult time priming itself if the tank has run dry. Since that's essentially what I did by removing all the fuel in the system, I am hoping this is my smoking gun. So, after I install the injectors and button everything back up, the EFI guide recommends topping the fuel tank off to help to prime the pump. Fingers crossed she can get rid of the case of hiccups. FYI- the gentleman doing the service on the injectors is a gentleman named Bill Johnson aka-Mr. Injector. You can read his stuff at Mr Injector - Home
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Old 12-24-2018, 02:23 PM
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Looks like you're ahead of me. I think I'll send him my injectors too.

Thanks for the lead and good luck.
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Old 01-02-2019, 06:34 AM
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I thought I posted this yesterday, but apparently it didn't go through. So, here's the update: After cleaning, sealing and reinstalling the fuel tank- a fresh fuel filter- injector service and reinstall- yesterday I turned the key. Attempt 1- nothing. Attempt 2- sputter. Attempt 3- ITS ALIVE! Runs and idled smoothly in the driveway for 10 minutes or so, so decided to do a road test. Here's what's going on:

Under hard acceleration, she pulls like a bat on fire! Under "feathered" acceleration, there's still a miss in the low rev range. It happens from idle to about 2500rpm, and then it pulls without the sputter. It is particularly obvious in 1st and 2nd gear. I also notice it when I am trying to maintain highway speeds and just feathering the accelerator.

Would love to have some expert ideas on where to look next. Fuel pump? Electrical? TPS? Help!!
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