olie05 Posted September 13, 2006 Share Posted September 13, 2006 First off this is a 77 280z with stock fuel injection and ignition. I'm on the freeway just cruising, all of a sudden the tachometer drops to zero. Its as if I had switched the ignition to acc, or off. Once I'm on the side of the freeway, I look under the hood and there are no obvious signs of gremlin sabatoge, such as a loose wire to the battery or anything like that. Heres what happens. The car will crank over, and it will fire, but once it fires it dies. I can get it to rev up a little by giving it throttle, but as soon as the tach passes around 1500 it flat lines back to zero, and the engine dies. ok sleuth away. Quote Link to comment Share on other sites More sharing options...
Sumo Posted September 13, 2006 Share Posted September 13, 2006 dying fuel pump? Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 13, 2006 Author Share Posted September 13, 2006 I thought about that, but according to the wiring, i don't see how it would cut ignition, and drop my tach to zero Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 13, 2006 Author Share Posted September 13, 2006 wait, doesn't the ignition switch send power to the ecu directly during cranking, but once it starts it must go through the circuits on the main relay? hmm... I'm going to look into that. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 13, 2006 Share Posted September 13, 2006 Sounds like ignition module to me. Does it run again after sitting for a while, then do the same thing again after you've driven around a bit? That would be classic module failure. Quote Link to comment Share on other sites More sharing options...
iaconsultants Posted September 13, 2006 Share Posted September 13, 2006 Are you running an MSD? I had the same issue with a MSD6A years ago. It collected to much humidity and shorted out. Bought a new one used silicone to seal it up and the problems went away. Good luck Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 14, 2006 Author Share Posted September 14, 2006 no msd. Stock ignition. After sitting it still acts the same. I'm not getting power to pin 10 on the ecu except while cranking. It shows 0v while in the "on" position, 12v while cranking, which explains why it will fire up, and then die. Now what is causing this lack of power to the ecu? Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 14, 2006 Share Posted September 14, 2006 Time for a Megasquirt, Olie, that's what my manual said when I checked the troubleshooting section. Quote Link to comment Share on other sites More sharing options...
iaconsultants Posted September 14, 2006 Share Posted September 14, 2006 I posted this to another post also with similar issues - thing that could cause an issue with the tach is a part in the distributor, we used to call the stator. It looks like a ring with a star on it. Check the teeth on this and make sure the gap is correct and use a brass feeler gauge not the ones containing metal. If it can be magnitized then it should not be used to check the gap. Quote Link to comment Share on other sites More sharing options...
TBK Posted September 14, 2006 Share Posted September 14, 2006 do yourself a favor and check your fusable links FIRST, try to recrimp/tighten them. Recently had ALOT of weird probs and EVERYTHING stoped when I changed them to the fuse block Mod! (77 Z) Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 14, 2006 Share Posted September 14, 2006 posted by iaconsultants:use a brass feeler gauge not the ones containing metal how does that work, exactly? Brass is an alloy of about 70% copper and 30% zinc, both of which are metals. Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 14, 2006 Author Share Posted September 14, 2006 do yourself a favor and check your fusable links FIRST, try to recrimp/tighten them. Recently had ALOT of weird probs and EVERYTHING stoped when I changed them to the fuse block Mod! (77 Z) Fusible links have been replaced with a fuse block and glass fuses. Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 14, 2006 Author Share Posted September 14, 2006 New info. When I turn the key to the acc position I can hear a relay click. When I turn it to the "on" position, I DON'T hear a relay click, If i crank it all the relays under the passenger side dash click. ...discuss Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted September 14, 2006 Share Posted September 14, 2006 Olie: I think you were on to something in post #4. You seem convinced it is something cutting the ignition. Are you sure it's ignition? I think power is sent to the fuel pump through the ECU once the engine fires up. I think the vane must not be fully closed for power to continue to flow to the fuel pump so the fuel pump will cut off in an accident. Maybe the wiring for this feature is bad. Can you test for voltage at the fuel pump or maybe fuel pressure at the rail to eliminate fuel as the culprit Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 14, 2006 Author Share Posted September 14, 2006 moms'z, Would that exlplain the dropping tach? A few more updates: Pin 10 on the ecu is only getting power while cranking, which means it is not normally getting power from where its supposed to be getting it from The main relay is fine. I pulled it and tested it. My ignition lock is funky and only cranks the car if you push the key in simultaneusly (oops, just gave away my theft deterrent secret) and if i turn the key to the start position, push it in to start the car, and then release the "inward" motion, the engine will stay on. I can rev it and everything, but as soon as i bring the key back to "on" the engine will shut off. The fact that the engine will turn on and act like normal indicates that there is nothing in the EFI circuitry that is faulty, just a power to the ecu under "on" condition on the ignition lock. I pulled the ignition lock/ switch, and tested for continutity and it all checks out. I think i have narrowed it down to missing power to a lead from somewhere. It seems like a blown fuse, but nothing is blown. I think i've checked the fuses 20 times now. Jeez I feel like i'm doing the whole ElaineZ posts over at zcar.com... Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 14, 2006 Share Posted September 14, 2006 Olie, do you think it might be either a faulty ignition switch, or the column multifunction switch? If it runs while you are holding the key in the on position, perhaps the culprit is a worn out lock cylinder or ignition switch? Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 14, 2006 Author Share Posted September 14, 2006 i don't think the ignition switch is the problem. I pulled it and tested for continuity through all ranges of operation, per the fsm. Another thing, when the key is in "On" position, the fuel gauge doesn't move up to where my fuel level is. (1/4 tank) Fuel gauge works if it is in the "start" position. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 14, 2006 Share Posted September 14, 2006 I've seen Saturns that will turn themselves off if the keychain is too heavy. The weight of the keys actually pulls the key back into the off postion. You don't strike me as the heavy keychain type, but the lock cylinder could be pretty worn out and not holding the switch in the proper position. The switch itself could still be good, but it's not staying at the proper angle, maybe. Quote Link to comment Share on other sites More sharing options...
SteelToad Posted September 14, 2006 Share Posted September 14, 2006 Same exact thing happened to me, I bought a new fuel pump, and filter before somebod suggested I clean the contacts on my relays. I pulled each of my relays, brushed the contacts, and still have the fuel pump and filter in their boxes. I guess if the relay isnt working right it'll get the initial burst of fuel to start, but not enough to run. Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 14, 2006 Author Share Posted September 14, 2006 well, so far I have pulled every single relay and reconnected it, and all the contacts appear to be alright. And besides, that doesn't explain how the car just all together STOPPED while i was cruising. Veritech-z this is for you, you be the judge I'm done working on the car for the day. I have some HW to finish before my 7pm class... I'm thinking about just jumpering the B and R terminals on the ignition lock harness and "tapping" the B and S terminals to crank it over... This seems to keep the engine running. I'm also thinking about getting a late 90's tercel. I think i'm going to put Z's on hold until I have a decent garage and unlimited funds to throw at one. Quote Link to comment Share on other sites More sharing options...
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