Turns but doesn't start

[Z Tyler Z]

First off I'm pretty new when it comes to fixing up cars and this 76' 280z is my first project car, that I'm trying to make a daily driver to replace my 92' cougar daily driver. My dads friend is helping me but he isn't the greatest mechanic either.

So after having this car started on me perfectly for the last month, after sitting for a weekend it doesn't seem to start anymore. It turns strong but just doesn't seem to go. So far we've checked all the distributor wires, it has gas and the battery has been fully charged, despite being in poor shape. We've tried everything either of us could think of. All we did before it stopped running was was replacing the shifter bushings and adjusting the E-brake.

All I can think of is that the battery clips (the part that attaches to the battery) are in poor shape. I don't know if that would cause it to randomly not start one day or what. Also we had recently taken off the hazard switch and console if that makes any difference, I'm pretty sure it didn't start before we did that though.

To top everything off I'm going on vacation (Arizona) in 2 days, I'm wanting to get it started before then, so I just don't stress my whole vacation.

Any ideas?

Edited July 30, 2009 by Z Tyler Z
Grammar

[KDMatt]

Hey Tyler,

Have you had a chance to check on any of your fuel stuff? The fuel-injection on these cars can be really sensitive and tricky to revive (but once you get it dialed-in correctly, it'll run flawlessly for a long time -- mine can sit for months and start back up again like it's only been sitting for a few hours).

How's your fuel pressure? Is your pump ok? What about your fuses? Fusible links? Is your coil working? Are your injectors pulsing?

[Z Tyler Z]

Hey Tyler,

Have you had a chance to check on any of your fuel stuff? The fuel-injection on these cars can be really sensitive and tricky to revive (but once you get it dialed-in correctly, it'll run flawlessly for a long time -- mine can sit for months and start back up again like it's only been sitting for a few hours).

How's your fuel pressure? Is your pump ok? What about your fuses? Fusible links? Is your coil working? Are your injectors pulsing?

Hey Matt,

So far I've yet to check any of the fuel stuff. When I try and start it, I can hear the fuel pump turn on though. After trying to start it for a while I could smell gas (flooded it) so I know it's at least getting gas.

If by fuses you mean the ones under the passenger side dash then , yes I already checked those when trying to solve my blinker problem.

Are the fusible links the links between the battery and starter? When I first went to start it one of those was unplugged. After plugging it back it nothing seemed to change.

Whats the best (and easiest) way to check if the coil is working and the injectors are pulsing? The coil is stock, so who knows how goods it's working after 33 years.

[KDMatt]

Hey Matt,

So far I've yet to check any of the fuel stuff. When I try and start it, I can hear the fuel pump turn on though. After trying to start it for a while I could smell gas (flooded it) so I know it's at least getting gas.

If by fuses you mean the ones under the passenger side dash then , yes I already checked those when trying to solve my blinker problem.

Are the fusible links the links between the battery and starter? When I first went to start it one of those was unplugged. After plugging it back it nothing seemed to change.

Whats the best (and easiest) way to check if the coil is working and the injectors are pulsing? The coil is stock, so who knows how goods it's working after 33 years.

You can see if your coil is any good by pulling a sparkplug and holding it against the valve cover (or anything electrically grounded ... wouldn't recommend your battery though, for obvious reasons) ... and as you try to crank the car over you should see the spark leaping across the terminals on the plug if the coil and plug are both any good.

The fusible links are contained in the two 'boxes' just in front of the battery. I'd have to find a picture to show you exactly what I was talking about -- they're basically wires that are designed to melt and break current if they're overloaded, like fuses more or less. -- What you're talking about, the things coming off of the battery are important though too -- one is the chassis grounding wire, and the other provides positive current to the fuel-injection goodies (someone else will have to step in to help me on this one... the drop resistor I think it's called?) ... so hooking those back up is kind of important .. .and if done improperly could screw something up.

You smell gas? That's a good sign, that means that its' getting to the engine, now just make sure it's not leaking all over something somewhere -- or more importantly, make sure it's actually getting squirted into the cydlinders...

Also, you might want to check and make sure all of your vacuum hoses are connected/in tact. (after 30+ years, if they haven't been paid attention to, I'm sure there have to be a few that are falling apart)... If you lose enough vacuum at the manifold you don't have a prayer of getting an EFI Z to start.

You can check to see if your injectors are pulsing two ways:

1 (the less accurate, but easier way) pull your plugs after trying to crank -- if they're all wet with gas, then you know ...

2 (the more 'official' way) -- take a multimeter, set to DC and pull the connectors off of the injectors, place the test leads into the +/- on the connectors ... and as you crank you should see the voltage spike/invert in very quick spurts.

-----------

I say look at your injectors first (especially if the positive terminal wiring is a bit suspect), and make sure they're doing their job.

If fuel, then check spark.

If you have spark AND fuel (which I somehow kind of doubt), then look at all of your vacuum hoses, especially around the brake booster.

I hope this is all helping so far.

Best of luck!

[sblake01]

You can see if your coil is any good by pulling a sparkplug and holding it against the valve cover (or anything electrically grounded ...

Careful there, you can send a spike back to the ignition module and fry it by doing that on a car with electronic ignition. That's a carry over from the days when all cars had points type ignition. (Ask me how I know!)

[KDMatt]

Careful there, you can send a spike back to the ignition module and fry it by doing that on a car with electronic ignition. That's a carry over from the days when all cars had points type ignition. (Ask me how I know!)

Hrm, I was completely unaware of that...

*Gulp* ... how do you know?

In that case Tyler, I'd recommend you find a cheap timing light and use that to make sure your coil is pulsing.

Edited July 30, 2009 by KDMatt
Had to ask the inevitable I suppose... ;)

[sblake01]

Hrm, I was completely unaware of that...

In that case Tyler, I'd recommend you find a cheap timing light and use that to make sure your coil is pulsing.

Apparently it doesn't happen everytime. I had actually tested coils that way myself even on cars with EI until the time I blew the module on my 78 which was about 12 years ago. I haven't done that since then. Why take the chance? The modules Nissan used on the 280Z that mount on the passenger side kick panel are hard to find and expensive when and if you do find one.

[Z Tyler Z]

Thanks for the input so far guys. I have to work most of today but when I get off I'll stop at my dads friends house (where the cars at) and start checking things.

I'm pretty sure my dads friend has a timing light we can use. If not I'll pick when up after I get back from my trip.

The fusible links are contained in the two 'boxes' just in front of the battery.

Ok, I know what your talking about now, I completely forgot to check those.

I'll also be sure to check the vacuums and injectors and get back to you guys tonight.

Thanks

[Z Tyler Z]

Ok, back from work and checking out the car.

We used a timing light and checked all the wires inc. coil wire and they all work great. I checked all the vacuums and it seems they must of have been replaced by a previous owner because they're all in decent shape (cracks or anything). The fusible links also look fine.

We used your method Matt and checked the injectors but the spark plugs didn't seem that wet at all, almost dry as if they weren't getting very much or any gas.

I don't know if it's possible to have all the FI to get clogged at once and prevent start up but I think it might be the fuel pump not delivering enough fuel to the injectors. Is there any way to check the fuel pump to make sure it's in working order. I might have been mistaken when I said that I herd it turn on. What do you guys think?

When I first tried to crank it over we noticed a little gas dripping from one of the tubes leading to the 4th injector. We tightened it up and it stopped leaking (very small drip).

So what do you guys think, whats the next step in troubleshooting this problem? Tomorrow is my last day I'll be in WA and be able to work on the car, if I can't figure it out tomorrow we'll have to continue this thread after I get back.

Thanks for all your help so far guys

[peterc]

Might be a clogged fuel filter. Remove the fuel return hose (the one NOT attached to the fuel filter) and insert it in a clear pop/water bottler. You should hear the fuel pump start when you turn the key to the "on" position. It should run for 3 or 4 seconds. If the pump is running properly and the filter isn't clogged the bottle should fill pretty rapidly. If not, then something is clogged. Could be the filter in the pump itself, the main filter on the passenger side of the fender or even one of the fuel lines themselves. Usual culprit in this situation is rust from the gastank. If thats the case a search of previous threads will show you how to clean/seal the tank.

Edited July 31, 2009 by peterc

[Z Tyler Z]

Thanks for all the help so far, I checked the fuel pump and it's in working order. I'll revive this thread after I get back from vacation and hopefully get this mess sorted out.

Thanks again everyone.

[Z Tyler Z]

Back from vacation, retested the fuel pump and it doesn't turn on when in the ON position. I used a multimeter and it looks like it's not even getting power. What does the relay under the dash look like? I can't seem to find it.

When I try and crank it over it squirts gas into the return hose, if that means anything.

A former mechanic friend of mine told me to run a wire from the battery directly to the fuel pump to test if it's even working. Is that safe?