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280z Cranks and Pops but won't start


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i have an 280z which for a while now has not been running but there were so many other things to fix i just put off the engine till the end. A while ago i had a mechanic look at the engine tell me that the injectors were not getting a pulse and the computer was shot so i got a new computer the injectos have pulse again but the car still didn't run so i changed the gas got new spark plugs wires and dizzy cap (they were shot any way) but now all it does is just pop a couple times when ever i try and start it but now enough to sustain its self. What do i do? Any help is much appreciated.

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the computer may have been fine but if your injector leads are toast it doesn't matter. changing the connections between the computer and the injectors is a cheap theory to test.

As far as timing goes if the distributor was removed one of the bright-eyed mechanics might not have marked the location of the distributor when he put it back. If that is the case you may not be able to adjusts back to the correct timing with the cog it's on (Although you will be annoyingly close) An easy, ham fisted way, to test this is by having someone crank the car and just turning the distributor and gauging how close the engine is to starting. if one extreme of rotation give more activity then move then remove the distributor and move it separate from the rest of the engine over one cog, rinse and repeat. If you have eliminated all systems except the ignition this is a good way to find an adjustable range. also check to make sure that all the ignition leads are in the proper order. I realize my last to theories rely heavily on mechanic stupidity but If you think about it they do this stuff all day and could not care less if it breaks so they are bound to make some mistakes. once a competent mechanic forgot to fully install the plugs. any way good luck

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It is back firing some times when i try to start it i dont think it is intake firing

i checked the timing it is fine and i got injector pulse from the injector plugs them selfs, thanks every body for helping me with this

 

 

Turn the engine to around 10 degrees before TDC by hand. Pull the cap and verify the rotor is pointing to the number 1 cylinder. Check your plug wires, make sure the firing order is correct.

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ok so i did as you said it is not on time not perfectly any way, but now comes the part where i look dumb i put it at 10 degrees before tdc but i dont know how to set the rotor to be firing on cylinder one, it is between one and two and i do not know how to move it and i am not sure if there are other things that need to be set diffrently aswell (I have no experinece with engines)

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When I bought my 71, 240 it ran fine so I just drove it until the engine started pumping oil one night. I replaced the engine with one from a 280 and when I pulled the distributer to place in the 280 engine I found that the plug wires were all one hole off. Seems the previous owner had installed the distributor one or two teeth off the proper setting. Might look into that.

I also bought a 54 Ford truck that a "Master Mechanic" had rebuilt but couldn't get it running again. It took me weeks of fiddling with to fix. Same symtoms as your "Z". Popping through the carb and backfiring out the exhaust. I finally found the wire going to the points had broken insulation where it passed through the distributor housing and was shorting the ground. I replaced the wire and drove the old truck for a long time after that.

Don't know if it would apply to your situation, but it might be worth looking into.

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hey so i set the timing and now the car starts and idles but if i step on the gas pedel it stalls not to mention there is white smoke coming from the tail pipe and smoke that starts to come from the engine after a minute or so thanks for even helping me get this far

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hey so i set the timing and now the car starts and idles but if i step on the gas pedel it stalls not to mention there is white smoke coming from the tail pipe and smoke that starts to come from the engine after a minute or so thanks for even helping me get this far

 

Have you done a compression test on your motor?

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the injector atomization could really just suck and so you are getting liquid fuel in the combustion chamber and it's creating a general flooded state randomly interrupted by stoich enough air fuel mix to support combustion then of course it is ruined again by the liquid fuel unlikely but, there's not that many thoeries left to test so it might be worth checking out your injectors

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