78 EFI L28 Randomly shuts off while driving wont start for 30 seconds. WTF?!

[Shawn MacAnanny]

I've been driving this car for a month just about every day now getting the engine to 100% before paint and such and i CANNOT figure out what the problem is. I'll be driving along, doesnt matter how fast, going around a turn, stopping, accelerating, there's no pattern to when it does it it just shuts off. Like fuel is cut to it. I can sometimes keep the pedal pressed down and it will spring back to life while coasting in about 15 seconds other times i have to pull over to the side of the road and crank it.

 

It doesnt matter if i leave the key on for a while to run the fuel pump, or i crank the engine sometimes it starts and sometimes it doesnt. Also sometimes it will run really rough when it starts back up. I have no idea what it causing this. The car runs PERFECT. I get about 26mpg (its a 5 speed), has a new head gasket, new FPR, cap, rotor, coil, wires, plugs, fuel filter, ive tested the AFM, TPS, ECT, cleaned every single electrical contact with Caigs DeoxIT, fuse pannel looks clean, everything just seems to be fine. I dont think its the fuel pump contacts in the AFM, the were fine when i checked them.

 

Does anyone know what it could possibly be? I have no more ideas. I dont think its a loose ignition as all my gauges and lights stay on and function. It's like the engine just loses fuel or something. It doesnt buck hard or anything though it just coasts as if i let off of the gas. If i push the clutch in its completely dead though.

 

Thanks for reading guys i'm at a loss for possibilities here.

[HowlerMonkey]

The little black box on the distributor is usually the culprit.

[Shawn MacAnanny]

What black box? its i coil distributor not electronic? I'm gonna go outside and look for it. I've had this distributor out a few times never payed much atttention to it.

 

Whats the remedy for this problem? New distributor? Can i take this box apart and fix it?

[HowlerMonkey]

I am probably mistaken on the module....don't remember what came on the 280z.

 

Was thinking it was a E12-80 equipped distributor but probably isn't.

[Shawn MacAnanny]

Ive been doing alot of research and from everything i have read i have narowed it down to the transistor ignition module which i found ot be water damaged when i inspected it so i have a new one on order and this should hopefully fix the problem.

[woldson]

What year? Oil pressure sensor by the oil filter on the my zx will fuel cut the engine if it looses continuity.

[Shawn MacAnanny]

It's a 1978 i will check that too although the gauge has never lost pressure. It seems low but i dont really trust that gauge any way

[19762802+2]

Have you ever had your tank cleaned? It could be sucking up chunks of crap from the tank.

[Shawn MacAnanny]

Actually i just did that and replaced a fuew fuel lines. I blew compressed air backwards through all the tank fittings and such to make sure the passages were clear (low pressure like 30psi) and cleaned the tanke really good with gasoline. Thre was a good bit of debris in there but nothing that looked like it would be clogging, barely any rust.

[stravi757]

I second it being the ignition module.

[Daeron]

It sounds like you have a good lead on what the problem may be, but I will throw a few ideas out for good measure in case you test/swap and still have the problem.

 

Have you pulled the plugs and inspected them after a stall? I mean, immediately after. Obviously this isn't going to be something you can do easily, just wondering. If the plugs look fuel-soaked when the engine stalls, it would point to an ignition culprit, and if they are dry then obviously the fuel supply would be suspect.

 

You said you tested all the EFI components... Have you also re tested each system from the ECU plug, checking the various components through the length of the entire wire harness?

 

I am suspecting what I call a "magic wire" somewhere, which is either grounding out your ignition and robbing you of spark, or dropping fuel (either through supply or through injector function; my brother's 280ZX had an injector resistor magic wire.) This may well be contained within the transistor ignition box, but as I said above, I am just brainstorming for alternative ideas.

[Shawn MacAnanny]

Well i have a new ecu, ignition relay, and ignition module on its way to see if it fixes it. havent gone through the entire ecu but my ignition module does look a little water damaged so i am thinking that might be the problem. Its very random. I can drive 500 miles and have it not happen once or have it happen every 30 seconds. It'll happen while dirving, around turns, straight line coasting, accelerating, braking, it'll happen after i park wont restart, it'll happen when its 90 out it'll happen when its 25 out. I've visually checked over all of the wiring and fuction all of the components best i can if this doensnt fit it then i guess i will have to do the ECU method

[vantage]

If a new ignition module wont fix it, have a close look at the ECU injector trigger connection, Coil (-) to pin 1 of the ECU. Loosing that connection (corrosion, vibration) would stop the fuel injection at once, effectively shutting down the engine.

 

What happens to your tach when the engine shuts off, does the needle drop instantly to zero (ignition failure) or does the tach still show the correct RPM while coasting (ignition still runs, fuel injection stopped).