Losing it!!

[BOMBAYBOB]

My 78 280 barely starts and throttles up and down once started. everything is new from fuel pump to injectors. cold valve is working, new cap,rotor, coil, pickup,wires and plugs. The plugs got fouled after a few minutes of this rollercoaster idle. I got the car after it sat in a garage for a few years. replaced the fuel stuff and it started and ran great.(at least the motor did) I started it each day for about a week, then this crap.

[280~Master]

What kind of fouling were the plugs? Fuel, carbon, oil?

You could have a bad ECU try switching with one that is good and see if that helps.

Fuel injector relays could be going out (located by the wiper tank.)

Your timing could be off

You could have the cap and rotor on wrong, I did this on my first 240

The wires could be mixed up on the cap

your pick up could be spaced wrong

What I would do first is test the ECU with another one.

Start double checking your self and make sure you replaced everything correct kind of like a process of elimination. Start eliminating with the basic stuff. make sure your getting fuel to the engine compartment. check the rotor and cap to see if the are right then double check the wires and make sure they are on the right way. check the pickup and timing. ect ect ect

[BOMBAYBOB]

Whats got me is It ran fine and then this without me touching anything. That makes me think something went. the fouling seems to be a combo. I def. smell fuel.

[sblake01]

I don't suggest swapping ECU's just yet. People always seem to suggest that but in my years of dealing with these cars I only actually seen one of those go bad and it was caused by the car owners lack of wiring skills. What John is referring to as 'located by the wiper tank' are actually dropping resistors not relays but I wouldn't look at those yet either. The statement "I got the car after it sat in a garage for a few years" leads me to ask if you checked the fuel tank for blockage caused by sediment from the old fuel. Fairly common problem on these cars when they sit for long periods with old gas in the tank.

[BOMBAYBOB]

I drained the fuel that was in it. I put about 10 gal of fresh fuel in the tank and drained that through a paint screen. It was free of debris so I used that fuel in the lawn mower. Filled it up with new fuel. is there something else I can check?

[sblake01]

Check the fuel pressure when you start it and see if it remains constant or drops as the car throttles up and down.

Edited December 6, 2008 by sblake01

[biddljj]

How did you drain the fuel ?

Have you replaced the fuel filter ?

Are you sure about the wire sequence on the cap ?

Not just a Z - zdisease

[280~Master]

What makes questions like this so hard to answer or help with is the fact that there is not really enough info, nor are you at the car listening, smelling, feeling, testing ect.

I would like to recommend a great piece of reading for anyone who has an EFI Z car.

This book in based on the 75 280Z but will work for your 76 280Z. 77-83 Z cars the EFI has most of the same basics but they do differ here and there and this book does not cover all for those cars.

http://www.atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf

Try some of the trouble shooting and see what you find. Let us know how it goes.

[BOMBAYBOB]

drained the fuel through the drain plug at the bottom of the tank.

Fuel filter has been replaced. I never touched the cap until the problem started.

Tomorrow: Fuel pressure, another timing check. I am noticing a stight tap in the top. Could a valve or somthing else up there cause this??

BTW I appreciate all the responses. Nice to know you can get info like this.

Thanks

[BOMBAYBOB]

Fuel pressure flucuates between 36 and 30 when throttles up and down.

Put in another fuel filter. Waiting for a timing gun

[DatsunZsRule]

Ahh another victim of "sitting for a few + years"

I realize that you replaced many fuel components and replaced old gas with fresh new fuel and thought that by doing that would solve the problems. Well Thats a start but more than likely not enough. If she sat for 3+ yrs, I'm willing to bet there is crap inside that gas tank and when the new gas gets sloshed around, the junk stuck to the walls/bottom of the tank is going to break free and clog components like filters, injectors ect. I bet the small filter at the inlet of your fuel pump is restricted bad too. have you looked at that one? Another common problem from sitting is corrosion on electric connectors from sitting which will cause lots of running problems on EFI 280Z's (Temp. sensor, thermotime switch, wiring connections to injectors to name a few)

I guess I'd start with dropping the fuel tank and have that thing either professionally cleaned or replace it and go through some of the basic things mentioned above then give it another try.

36 PSI is perfect, but what does it read when the idle problem starts? If it drops, it's like I said earlier, The junk is getting stirred up and restricting fuel flow more than likely.

Just my thoughts Trust me, taking on a Z or any vehicle that has been parked and sitting for months or yrs. is no small project.

Best of luck.

[sblake01]

Fuel pressure flucuates between 36 and 30 when throttles up and down.

Put in another fuel filter. Waiting for a timing gun

It should pretty much remain constant as 36. Does it go continue to go down causing the car to stall? If that's the case it sounds to me like DZR's synopsis is accurate. My car sat for four years before I got it and exibited the same symptoms. Eventually replaced the tank and it's been running ever since, over 11 years now. Edited December 7, 2008 by sblake01