Was running great, but then on the way home it just died

[Gary L]

I've got a 76 280z 2+2 with EFI that I've been "refreshing" over the past couple of years. Everything is pretty much stock. I've just recently been taking some test drives and as mentioned it seemed to be running great. Then on the way home after turning off on a side street at about 20 mph it just died. It happened so fast I'm not even sure how to describe it. It's kind of like it lost all power or else its like the new fuel pump I recently put in quit or ... Like I mentioned, it happened so fast I'm not sure what happened. So I coasted to the side of the road and when I tried to start it, it fired right up. So I continued heading home, which was only about 1 mile away, and about half way it kind of chugged for just a second while the tach shot up momentarily to about 3K and then it ran fine again the rest of the way home. When I got home I kept it running in the driveway and gave it a quick look over and could not find anything wrong. I rev'ed it up a few times and it ran great. Bummer. Now I'm going to be gun-shy about taking it places.

 

Anyhow, has this happened to anyone else? Any thoughts on what could have caused it or what I should be checking first?

 

Thanks

Gary

[SteveJ]

Check for rust in your fuel tank. Install an inline fuel pressure gauge under the hood and check the pressure when it's acting normal and when it's acting up.

 

Clamp off the return on the fuel pressure regulator and see if it maintains pressure. The symptoms sound like not enough fuel from the pick-up or pump getting clogged, though.

[Gary L]

I know my description of what happened is kind of vague, but it happened so quickly. It was almost like someone pulled the plug! Or like my ECU shut down, which I'm sure didn't happen. Right now, its running great so I'll have to see if I can get it to happen again, while close to home. I did once have an electric fuel pump quit in the family van while cruising on the highway and it died instantly, no chugging or spit/sputtering. So may be something did momentarily clog the fuel pump.

 

Anyhow, I was hoping someone else had a similar experience and a suggestion on what to look at first. I will do some checking of the fuel pump first (eg,electrical connections, etc)

 

Gary

[Zed Head]

 on the way home after turning off on a side street at about 20 mph it just died. It happened so fast I'm not even sure how to describe it. It's kind of like it lost all power or else its like the new fuel pump I recently put in quit or

 

it kind of chugged for just a second while the tach shot up momentarily to about 3K and then it ran fine again the rest of the way home. 

It may be that the two things aren't related.  SteveJ seems on target.  Were you taking a left turn the first time, at a fair pace,with a tank less than 1/3 full?  The 280Z's fuel tank baffling is known to be deficient at low fuel levels.  The fuel pump runs dry on left hand turns.  I've had it happen but it starts right back up once it straightens up.

 

Is your car a manual or automatic?  An automatic might just die and not restart.  I have a manual transmission so the engine keeps turning when it happens.

[siteunseen]

When I first got my '77 it would suddenly die when I pushed in the clutch.  The BCDD was out of adjustment.  It's something that lets them gradually drop in RPMs to keep from stalling.  Another thing that may have happened, the EFI connector by the battery may be loose?  It may have just been letting you know who's the boss. 

Mine does some weird stuff sometimes too, but it has never left me stranded.  Gremlins.

 

[SteveJ]

If there are some big rust flakes, they could get caught against the fuel pickup, blocking it. The car stalls and the fuel pump stops. The rust flakes fall off the pickup tube because the pump isn't drawing, and the car will start right back up.

[Zed Head]

On the pickup tube blockage - I think that engines tend to rev higher as they go lean, like when they're running out of fuel.  Especailly if they're running rich beforehand.  So that might explain the rev to 3000.

 

The difference between the two potential causes is that the left turn baffle problem is reproducible.  So, if you can get the engine to die on a left turn, repeatably, that would lean towards the low fuel/poor baffles theory.  If it's random, clogged pickup.

[zKars]

If the car was under power (foot on gas) and the car instantly died (no chugging, slowly dying over a few seconds) then its ignition cut-out. Bad Ignition unit or coil. FI cars can die quickly if the fuell pressure goes away quickly, but it's not instant. And it doesn't come back two minutes later when you re-start the car.

Just probabilities here, but my guess is ignition box under the dash or the coil.

[Zed Head]

If the car was under power (foot on gas) and the car instantly died (no chugging, slowly dying over a few seconds) then its ignition cut-out. 

Actually, this is exactly, to the T, how the engine dies when the fuel pump runs dry om a corner because of poor baffling.  I should mention that it will also happen on a right hand turn, but it starts sooner (with more fuel in the tank) on the lefties.  I have a certain corner that I accelerate through, from a stop light, and it will happen every time if the tank is getting low.

 

Only adding for clarity.  The repeatability will tell the story on that possibility.

[Gary L]

Well, it just so happens it was a left hand turn, however, I did have around a half a tank of gas. Also, the roads out by me are really rough and I was driving fairly fast with all the bumps jarring the car quit a bit -- possibly this did stir up some rust in the tank? . I probably won't have time to try it again until this weekend, but I'll try the hard left hand corner again. May be I should pull the gas tank drain plug to see how the gas looks? I did this a few years ago and it was clear, but may be not now. I'll also check the EFI connector by the battery.

 

Gary

[Gary L]

I thought I'd take a quick look at the EFI power connector since this is an easy first thing to do. I've cleaned a lot of connections on my car, but I must not have ever looked at this one. It, or should I say, they, were kind of corroded-up. The reason I said they is; 

 

why does a single lead for this come off my pos battery terminal to a connector, then 2 wires come out of that connector for about 4 or 5 inches to another connector which then has a single wire again coming out of it which runs to the dash? Can't I just eliminate those middle 2 wires between the connectors or are those some kind of fusible link?

 

I guess I just never looked at those wires that close before. But they were pretty corroded so I'm cleaning them up.

 

Gary

[Chickenman]

Edit: Was typing while Gary made his post above. Continue checking all of your electrical connections. Don't eliminate any of those wires.

 

In addition to the above, check ALL of your grounds and electrical connections, particularly to the ignition system. . Bad grounds can do flaky thing, are intermittent and rough roads as you mentioned can make them rear their ugly heads. Carefully check the small wires that attach to the pickup coils in the Dizzy. These can crack and short, causing intermittent failures. Fairly common problem with Magnetic pickup coils.

 

I do agree with Jim that Fuel Pump failures on EFI cars usually give some type of warning, usually by a short sputter... even with a complete failure of the fuel pump. The fuel rail still has to bleed down pressure and that gives a bit of warning ( sputtering before dying ) . And failed fuel pumps usually don't recover. Clogs or fuel starvation in turns usually give even more warning as fuel pressure will fluctuate.

 

Ignition failure on the other hand are INSTANT. And they can recover if a bad ICM cools down or a bad ground makes a " better " connection. BTW... bad grounds will heat up ICM's until they fail. Can be an SOB to track down.

 

In my experiences and just my .02c... FWIW.

Edited August 12, 2015 by Chickenman