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83 280zx N/A running issues

3008 Views 9 Replies 6 Participants Last post by  rogerz, 
B
I have an 83 280zx that was running a little rough. Back firing until around 2,500 rpm or till the motor warmed up. First I replaced the fuel regulator, because the one on there was already kinda broke when it was put on. It continued to run rough and eventually didn't start. So then i thought it was a timing issue. I re-timed the cap a rotor and still wouldn't start. So that was the last i did to it, I have been out of town for a week and now I went out tonight to work on it and not it just turns over with no combustion. Would this be a result of a bad coil or bad timing? Or could this be a fuel problem? Fuel is getting to the injectors, I pulled the fuel lines to check.
Thanks
83 zx, I live near Wichita
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Start with the inexpensive things first. Change out the fuel filter, it could be clogging. Disconnect a fuel line going to the injectors and spray some carb cleaner in there to dissolve any varnish that may have formed. Check and clean spark plugs. Make sure all connections on the battery and the starter are clean and tight. When you turn your key in the ignition, listen for a low hum - that's your fuel pump pressurizing the system. If no hum, check to see if your fuel pump has gone bad.
Check vacuum hoses on your manifold. If you have alot of broken or worn hoses, they could be allowing excessive amounts of air in which could be the cause of the rough running and eventual inability to start the vehicle. I found this out when I accidentally left my break booster hose off when replacing it and tried to start my '82 280ZX with no luck.
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No spark, never start.

I would pull a plug first, put it back on the wire, set it on the valve cover or other grounded surface where I can see the tip and turn the engine over. Or you can pull a spark plug cap and stick a bolt or a nail in and do the same. If you're getting spark then you can move on to fuel, timing, other issues. If you don't have spark, then work your way backwards to the cap, rotor, coil, ignition module, pickup coil, etc.
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J
I agree with PDX, check for spark and fuel. Do you have a pressure gauge on it. If not I would recommend adding a pressure gauge after the fuel filter. It is invaluable when diagnosing problems. If so what is your pressure when cranking? You should also put a noid light on injector wires to ensure they are getting a signal. Make sure you put the wires on the distributer cap in the right places, not that you don't know what you are doing but it can be easy to overlook.

Another thing I would look into is the cold start system. I don't think a problem with it is necessarily causing your no-start problem, but it make have been causing some of the running problems if they only happen when cold. Check the thermo time switch, AAR, and cold start valve. It may be that the AAR is not opening, causing it to run rich when cold (less air entering the combustion chambers than should be, as the AAR allows more air to bypass the throttle when cold). Or the cold start valve may be acting up, spraying to much or too little fuel.

Also make sure that all the air hoses are intact and have no holes, those can cause lots of trouble. Is the car in a restored state and just started running rough, or are you trying to fix it up?
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R
check the fuel pressur (pic). run a test on the chts per fsm. download that from xenon web site. clean afm, ecu and tps electrical connectors with Deoxit from CAIG. Put a vaccum gage on it and check that. under 18 sucks, 18-20 ok, above 20 excellent.
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check the fuel pressur (pic). run a test on the chts per fsm. download that from xenon web site. clean afm, ecu and tps electrical connectors with Deoxit from CAIG. Put a vaccum gage on it and check that. under 18 sucks, 18-20 ok, above 20 excellent.

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Well, , im going to say that the coil/rotor/cap is bad.Also i might add in, if its been wet outside, check for moisture in the cap. If you have fuel to the injectors, then the fuel isnt the issue. Injectors dont just all clog up at once.Also as they said, check vacuum lines,But even if it was a dead vacuum line, the thing would most likely still fire/attempt to start. On my 80 280zx the cold start wires that connect to the unit arent there.When its cold, I always have to sit for a few minutes and let it warm up enough to back it out of the barn. Does anyone know where the cold start lines go, so that i might could wire them back in? theres no trace of them being cut out.
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Thanks for the help Guys. I wasn't able to work on it today, so ill get to it tomorrow. It is my daily driver so I'm starting to realize how hard it is with out a car. I will check coil and plugs along with cold start. Ill let you all know how it turns out.
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B
Ok so i had another coil laying around a went ahead and changed it out, because i had no spark at the plugs. I checked again and still no spark! I took the wire from the coil to cap and grounded the cap side and left the other in the coil and had some one turn over the motor. No spark! I came inside and checked the manual and found the power circuit. The red and green wire on the the dis. I went back out thinking maybe i knocked them off by mistake while re timing, and nope. They are sill there. I currently don't have my volt meter, died the other week, So it kinda makes it hard finding electrical issues. Any one have any ideas?
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R
unless you are really broke (in which case you shouldn't own a Z money pit) Lowe's, Home Depot, Harbor Freight and as a last resort Radio Shack sell inexpensive analog vom. that is plenty good enough for auto work you aren't doing electronics. Mostly you want to know continuity or +12 volts DC. thermo time switch only fires the cold start valve so doubt that is part of the problem.

1980Datsun Did you ever think to download the fsm from xenon and then look at the schematic probably tells you where the wires go to/from. take a thumb drive down to kinkos and tell them to blow it up to 11x17. much easier to read.
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