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Just because I hate when people dont post the resolution, im following up on this. Just an overview: I have a dual pickup distributor. The 2nd pickup has a switching relay located on the passenger side just under the fusible link boxes. Its controlled by a temperature switch with a blue and black wire coming off of it (not to be confused with the coolant temperature sensor). The black wire is grounded and the blue wire goes into the loom and switches to red via a bullet connector. I unplugged the connector thinking that the open circuit would be ok. I was wrong, it made the problem better somewhat but very sporatic past 4.5k. I grounded the red wire tonight and heard the relay switch over. My problem magically went away. Revs all the way up with no hesitation. I know this sounds simple enough but the car didnt run when I bought it so I had to look at every aspect of the car and start from ground zero on everything. So I suppose the permanent fix would be to replace the switch, but to be frank I dont really care. I just permanantly grounded it and called it good. Its one less thing to worry about. I dont think this system was used long (75/76) but to anyone having similar issues, I hope this helps. -Josh

Its back again, on the way home it was acting up again. Im at my wits end. I understand some of this now, I have a dual pickup distributor, so that switch controls my timing. searches didnt give me much as these dont seem to be all that common. It looks as though one of green wires is grounded on the dizzy. Can anyone enligten me on what I should do? Id like to get rid of the ballast resistor so can I get rid of one of the pickups or what? -Josh

Thanks everyone for the help so far, I tried swapping the afm today, that didnt help on the top, but it did seem to run better over all after I got it dialed in, although I did put the old one back in just so Im not all over the board replacing and not realizing if I do fix the problem intermittently.. I still am in no better shape than I was, but Ill keep at it. -Josh UPDATE: Believe I found it finally!!!! If I unplug the coolant sensor thats grounded it revs and actually goes!!! WTH is this sensor and what does it control, its not the coolant temp sensor (thats new) or the thermotime sensor its the one with one wire to ground on the block and the other goes to the wire loom its blue, then goes red after the connector. Thanks -Josh

ive checked the tps, ive cleaned it, ive ohmed it out, everything tested fine, ive adjusted it just to see if it was richening the circuit too early....no go on any of this. I dont think another tps would help since its just 2 sets of contacts. I feel that the problem might be somewhere else and maybe the tps is sending just enough fuel to make it choke, which makes me wonder if its possibly the afm screwing up since this is pretty much the only other thing that controls fuel mixture!? When I ohmed the afm my reading were about 40 ohms off on every reading...so could this be a problem? Hell I dont know at this point!

Ok, tonight double checked over everything. Replaced connectors on water temp sensor. Got the meter out and followed the "bible" to check all the efi components to no avail. I drove it tonight and plugged in and unplugged the throttle switch with the same results. I can get to redline without it plugged in, but if I plug it in 5k is all she wrote. I just dont understand what it could be. Plugs are still white. I understand newer efi alot better since I was a ford sho fanatic for years. But this as simple as it is is mind boggling to me. Anyone got anything? Anything at all?? -Josh

Hey bud, ive had a breakthrough!!! After you posted this message I got curious. I was at the inlaws house and decided to unplug the tps for the ride home since it was a 65 zone and I could wind it up a bit. I can actually rev into redline with it unplugged! I guess this means im fueling rich on the top side. You can definitely tell its unplugged since it idles funny and it doesnt rev fast on the upper rpm range but it does rev! Ok so what would be my plan of attack on this? I understand how the tps works but its just a fuel enrichment... need some help on this one!!! Thanks again for everyones help thus far. -Josh

Well, I replaced the injectors and all associated rubber lines last night...WOW what a night and day difference. It revs up to around 5k now. This fixed about 90% of my problem.... Now I feel like my timing may be off. Im going to work on my distributor today. I think I have a points setup, if so it may be time for an upgrade. OK while I was driving tonight, I in neutral I can go straight to redline no problem, but when im driving I get stopped at 5k. Can this be timing related or what am I missing here...im out of ideas. Please help.... -Josh

While I appreciate the thought... I dont believe my year model has a crank sensor since im not run off of coil packs. Thanks though...definitely need all the thoughts I can get. Hey blue72, did you ever check your plugs to see what they looked like?...I would definitely chalk it up to spark cutting out, but my plugs tell me that im not fueling..

Anyone have any insight here? Is there anything that would cut my fuel out in the higher rpm range aside from clogged injectors? its just really getting me because all the plugs are ghost white. !ts just hard to believe theyre ALL clogged. I do have different colored injectors though. a couple tan ones a couple brown, and one green which is a turbo injector i think...help please

Ok checked my fuel pressure, it spikes to around 40 when I floor it then settles back to about 34 psi at all rpms. Also replaced coil with accel just for peace of mind. Also checked valves which are within spec. I guess im down to injectors? My plugs were really white tonight after a drive. Could a loose valve cover introduce a lean condition? I wouldnt think so..buttt...

I pulled the lines off the tank today and checked the pump, its a aftermarket style with no strainer (that I could find) built in it. Gas poured out of the tank so I think im good there. Im going to check the fuel pressure after I go buy one tomorrow. Im really stumped. I also did a plug chop. For those not familiar thats where you put it to the rpm you want to check which in this case is 4k and cut the ignition. Plugs were white...so lean, so I think I can rule out a ignition problem...I THINK! If it were ignition problems the plug would be wet from fuel with no spark..am I on the right track?

Ok Heres where im at. This car sat for 2 years before I bought it. I got it running and driving but I have a couple issues. The facts: New coolant temp. sensor (it tested bad, which is why the car was parked by p.o.) New Ngk plugs gapped .040 New fuel filter Air filter is good. Any vacuum lines that wer rotten have been replaced. tps tested, and adjusted compression test revealed 150 +-5. Test was done cold. all connections seem to be fine csv/ thermotime seems to be working as they should Plugs looked ok, except #6, which looked rich. What would cause this? Heres the problem under load, idle is ok, driving is ok, around 4k it doesnt want to accelerate any further almost as if my fuel is being cut, now if I let up a little (maybe 2/3 instead of wot, it will accelerate but not fast. I cannot tell if i have a weak spark or lack of fuel or something else im not familiar with. The only variation ive seen is it seems to lack a little around 2500 now almost like a miss, this just started tonight. Im just really confused. Thanks -Josh

Ok heres what I learned tonight so far. Did a compression test: 150 psi +-5. I did it cold so results are probably a tad low. When I pulled the plugs, I found 1-5 looked ok a little black but ends were tan, but 6 looked black as coal. Not sure where to go from here. HELPPPP! Thanks Josh

Played with it some tonight. Im hesitant to drop the pump to see if there is a filter in it...can anyone confirm this? Also it really seems to be running terribly rich...I smell like fuel after being around it for a few minutes, and it puffs a cloud if it sits and idles for a while. Kindof like its loading up. Any insight here? Anyone??... Thanks Josh

Hi everyone, im new here just picked up a 76 280z that hadnt been started in 2 years. Ive been through the manual, the efi guide and lots of posts. I have plans to restore this car, but would like to get it up and running to par before tackling some body rust. I do have it running and driving. The reason it was parked was because it kept fouling plugs. I replaced the plugs with NGK gapped .040 and found the coolant temp sensor was faulty. So I tagged it this morning and took the day off to waste some gas and see what needs work first aside from the body. Heres what I found: The Z runs good up until around 4k and at this point spits sputters and doesnt want to rev any higher. If I rev it slowly it will rev to redline but cracks like fuel starvation. Ive replaced fuel filter and fuel line attached, checked all connections and unplugged each injector. It stumbles so I can tell each one is firing. AFM seems to be working fine, checked TPS, checked vacuum lines and replaced any that were suspect. What else can I check, without dumping hundreds in injectors or a pump. I have run one can of seafoam through the tank. Any help is appreciated since fun doesnt begin til 4k. Thanks Josh