78 280Z - no injector pulse

[FastWoman]

I agree. And don't go pulling injectors! Pulling injectors can open you up to having to do other stuff -- replacing O rings and insulators, replacing fuel lines, or even mucking with screws rusted in place (like on my engine). There's a much easier way to verify flow if your system holds fuel pressure: Put a fuel pressure gauge somewhere on the fuel rail (or between the filter and the rail). Briefly run the fuel pump to pressurize, stop the fuel pump, and then ground an injector to depressurize. If you don't see the pressure drop when you ground an injector, then you have no flow. Easy.

[Zed Head]

Here's a cheap ECU that might be worth a shot, for testing. Should work even if the numbers aren't a perfect match. The differences are minor among the variations.

280z parts/ FREE L24 / Price drop - Parts for Sale - HybridZ

And superlen has been known to loan an ECU I believe. He has collected a bunch for his project.

http://www.classiczcars.com/forums/fuel-injection-s30/51601-hellfire-status-release-date-annouced-2.html#post463189

Edited September 3, 2014 by Zed Head

[Virto]

I thought the ECU was different for 77-78 versus 75-76...am I mistaken?

[Zed Head]

They are different, sometimes, in ways that I'm not clear on. But the injector grounding circuit is the same. It might give you enough to get the engine started and get the car home.

I had a 76 and 78 280Z with exactly the same ECU's, but the number on that 1975 ECU is different. I only suggest it because it's cheap, $25, and might tell you something, if you get to the point where the ECU is the only possible source.

The weird thing about your situation is that the engine ran when you drove it over there and then it just sat. The ECU is in a fairly dry spot and I think that they probably go bad from usage not sittage. Odds are something strange happened like your gas tank filled of water. It happened to EuroDat and he was using his car.

If your guy decides to really go for it with some time, he might run a hose from a gas can to the inlet of the fuel pump with fresh gas. Especially if the injectors click.

[Virto]

I'm tempted to just have it towed home, but I'm going to see if I can get some more garage time this weekend. I'm also going to see if I can pick up that ECU - I'll let you know how it goes.

Edit: Went ahead and bought that ECU. Even if it's only a pseudo-spare, it'll be nice to have on-hand just in case.

Edited September 4, 2014 by Virto

[Virto]

ECU will be here Monday - swinging by the shop tomorrow morning to ground the injectors and see if we can get a click. I should have an update around lunchtime and I'll come back to beg for help after that.

[Zed Head]

I don't know whether to hope you need the ECU or not. If you do get clicks from directly grounding the connectors, then find on Monday that the 75 ECU gets the car home, there's somebody selling a 1978 ECU on Hybridz.

Good luck.

[Virto]

OK, wow - what a weekend.

Friday afternoon a big storm cell moved across the Elgin area, 70MPH winds and quarter-sized hail. There was one funnel cloud reported about halfway between here and the office in Arlington Heights.

I lost the fence and all power until literally 10 minutes ago. The first thing to do was restart all the fish tanks - looks like I may end up with some dead loss in one of them, but we'll find out in the morning.

Now, the storm essentially passed right by the Z and the garage it's at, which is less than 2 miles from the house. I ran over there this morning (errand day, what with no power at home, and all). Grounded the injectors out via the ecu harness and got clicky clacks from each and every one. Drained some of the gas and found it clear, free of water and with no varnish smell.

The ECU will be here Monday afternoon - I plan to jet over there Tuesday morning just to see what happens. I also told him to go ahead and hang the rest of the exhaust and push come to shove, I'll tow it home if need be.

[FastWoman]

Well, you've got...

1. Power to the injectors, which operate when grounded. (Therefore working drop resistors, etc.)

2. Power to the ECU. (Therefore both EFI fusible links and the fusible link relay are good.)

3. Good ECU ground.

4. Likely good connection between ignition coil (-) and pin 1, because tach bounces when cranking, and you have +12 at pin 1 with key on.

5. Fuel pressure

6. Typically pathological priorities at a time when your power is out, your fence has blown down, and your fish are suffocating.

Assuming your mechanic was correct that you have no injector pulse (and I'm not totally convinced yet), then it does seem likely the ECU is bad. It will be interesting to see what that '75 ECU does for you.

[Zed Head]

Bummer that you were short on time. Good though, that you got injector operation. Narrows things down a little more. I wish that you had run the other coil grounding test (three taps and a click). That would have shown if the ECU could work with the proper Pin 1 signal. Grounding the coil is like the best on-off ignition module signal the ECU will see. If you're going to have it towed if the 75 ECU doesn't work it doesn't really matter right now anyway.

The 1975 and 1976 EFI diagrams are identical as are the the engine parts. Operation should be identical, it's probably just a different set of electrical components in the ECU box to do the same functions.

[Virto]

I would have done the coil grounding test, but I forgot exactly what to do - and no power meant I couldn't jump on and check.

If I was smart, I'd have brought a charger to the garage with me and charged my phone and then looked - but I was a bit preoccupied. Hopefully I can avoid the tow, as it would just be 100 bucks down the drain, but we shall see. Tomorrow is fence repair day, but I'll be taking a nice long break for the Bears home opener.

[Virto]

OK, it arrived today - he was closed, but I couldn't wait, so I zipped over there, plugged it in and turned the car over.

Same sputter as before, then dead. Flat battery. So no real verdict as of yet. I did notice a code enforcement officer in the next parking lot over ticketing a boat that was being stored - probably expired trailer plates - so I locked the car down and got out of there before I drew any attention to myself.

So anyway, further updates as events warrant, I guess.