k204drek Posted June 12, 2012 Share Posted June 12, 2012 My 280z will only run if hold it to the floor and it will only be at like 1200 rpms and if you let off and it dies it will not crank back up and after trying and trying it backfires REALLY LOUD and blows a puff of smoke and still wont crank. My gas tank has just been re-done and it ran fine for awhile (good enough for yard driving) but then i went out to crank it and it did that so i waited a few days and it did the same thing. PLEASE HELP. Quote Link to comment Share on other sites More sharing options...
OldAndyAndTheSea Posted June 12, 2012 Share Posted June 12, 2012 Sounds like an air problem? Since the car will only run with the pedal floored, this means the throttle body MUST stay wide open to get enough air for combustion. First, I'd check for vacuum leaks. Then I'd investigate the air flow meter, as these are often the weakest link of the equation. Google: "Datsun Efi bible" if you haven't read it already, I feel this will make you 100% more confident in regards to the Bosch injection system. Best of luck! Quote Link to comment Share on other sites More sharing options...
loy Posted June 12, 2012 Share Posted June 12, 2012 Afm can stick, try moving the flap by hand. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 12, 2012 Share Posted June 12, 2012 Kind of sounds like low fuel pressure, with the recent tank work. WOT lets more gas out, apparently just enough to start or get one lean back fire. Measure fuel pressure. Quote Link to comment Share on other sites More sharing options...
S30 SPL Posted June 12, 2012 Share Posted June 12, 2012 Or it could be that the fuel pressure regulator is stuck closed and the pressure is too high requiring a LOT of air to get the car to run. Mine failed before, thank goodness for aftermarket and a gauge. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted June 12, 2012 Share Posted June 12, 2012 Actually sounds like the opposite to me. Sounds like low fuel pressure. Low flow = engine barely running. This is also supported by the fact you just serviced the fuel tank. I would replace the fuel filter (hopefully with a clear window one) and see if it works after that. The window will allow you to see if it's clogging up again. DO NOT run w/o a fuel filter, or you're asking for clogged injectors. What all did you do to the fuel tank? Crap in the tank or loose paint will muck things up quick. Best to have it boiled at a radiator shop. Yes do check that your AFM flap isn't stuck too. but I think it's your fuel filters. 280z's have two filters, one back by the pump and one up front on the fender before it goes to the fuel rail. Phar Quote Link to comment Share on other sites More sharing options...
S30 SPL Posted June 12, 2012 Share Posted June 12, 2012 There is a filter in the rear? I haven't seen a filter back there on mine, just a pump and a damper. Quote Link to comment Share on other sites More sharing options...
yhlz Posted June 13, 2012 Share Posted June 13, 2012 Check your chasis grounds. I had the same problem. Quote Link to comment Share on other sites More sharing options...
yhlz Posted June 13, 2012 Share Posted June 13, 2012 Sounds like its not cranking because the engine floods the spark plugs with gasoline. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted June 13, 2012 Share Posted June 13, 2012 maybe not all cars have the rear filter. the few I've had, have had them. an inline before the pump and another just after the hard lines before the engine. (in my 280z's, the 260 I had and my 240 both only have one filter.) In anycase. He said the car runs if it's floored. Is it belching black smoke? that would certainly show it's too rich, and be an air problem. No smoke at all, I would think it's not getting enough fuel. Could be the cold start injector is stuck open. Another test you can do is to get starting fluid , clamp off the fuel line and start it off the fluid. if it runs well while spraying that in, then it's probably not the air flow. if not then it could be your AFM. Since you just had the gas tank out, like I said before, I'd suspect it has to do with that. Quote Link to comment Share on other sites More sharing options...
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