stprasinz Posted July 18, 2010 Share Posted July 18, 2010 (edited) just as the title says my car (1981 280zx turbo) only runs when the fuel pump is switched off.... If I energize the fuel pump the engine shuts off instantly! I had it running for approx ten minutes with no fuel pressure... hopeing that it would stall and then run correctly... with no luck.... So I decided ok some fluke here.. I'll pop off the pressure line spray fuel all over, and then it'll run right.... No I removed the pressureized side of the fuel line, and it didn't spray, none even came out!!!!!... and it still runs!!!! This is not a lie! I have my car seriously stranded at my buddies house 10 miles from its home (MY DRIVEWAY) and I'm stumped... I'm going today with the factory fuel pump, coil, new plugs, And lots of hope lol.... anyone have anything to try??? I also checked the injectors are getting pulsing signal.. If I unplug 1 it sounds different 2 it chugs 3 barely runs 4 it won't run... So I think the injectors are not the stuck open... hmmm oh andf heres an odd one, it sounds muffled?? very quiet and it was running fine before this.. I was just going to crank up the boost as a matter of fact.... now this And I might add, thats it sounds almost normal with the fuel pump off, but when you can get the fuel pump on, and the car running (the more I messed with it the less that happened to the point where now when I turn on the pump it instantly dies... wanted to throw that in, so its not the exhaust is plugged blah blah blah we were joking about a youtube video busting on the honda that ran water in the oil... this car doesn't even use fuel!!!! it runs on air, talk about fuel economy, the applications are limitless.. lol Edited July 18, 2010 by stprasinz Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted July 18, 2010 Share Posted July 18, 2010 you shue the motor isn't equipped with a mech pump? Maybe a SU motor from a 280Z got dumped in and the turbo bits bolted on after a HG blew at one point by a previous owner? if the pump if locked up running it could just block the system from cavitation or something, while leaving it off means the mech pump draws fuel through? Quote Link to comment Share on other sites More sharing options...
stprasinz Posted July 18, 2010 Author Share Posted July 18, 2010 ... unfortunately no... it doesn't have any other pump mechanicle, or electrical.... actually its a 1981 turbo motor recently rebuilt running the factory ecu and such, walboro 255 pump in a 77 shell.... it was easier to say it was an 81 280zx turbo... i'm still baffled how it ran for sooooo long with the fuel pump shut off, I even have a fuel pressure gauge on it... and it says 0 psi.... As soon as i energize the pump the gauge shoots to 38-44(38 while idleing and 44 as soon as it dies.....) and the car stalls out instantly!!!!! gonna run some more tests and slap some various parts to her and see how she likes it.. gonna start by replaceing the plugs and trying to start it..... nothing more.... if that works great.. if not, I'll install the old coil I have and try that, if still nothing, original fuel pump...... from there towing it to my shop..... Quote Link to comment Share on other sites More sharing options...
stony Posted July 18, 2010 Share Posted July 18, 2010 Can you rev it ? or is it just an idle thing. Has it been running fine then all of the sudden this happened or is it a project first time start up? Somehow you are getting pressure to the rail???? maybe return and supply fuel lines reversed? can you hear the fuel pump running? are you just assuming its running cause the switch is one? wired backwards? Quote Link to comment Share on other sites More sharing options...
abc_was_here Posted July 18, 2010 Share Posted July 18, 2010 (edited) When my car ran on no fuel pump it tuned out to be the ECU, the injectors were held open and as long as there was enough gas in the tank it would just syphion it out as long as i primed it with the pump first....Try and find a friend or someone with an extra ECU -And it ran horribly, which im assuming yours is too and mine would eventually cover the plugs in so much gas then wouldny spark Edited July 18, 2010 by abc_was_here Quote Link to comment Share on other sites More sharing options...
stprasinz Posted July 18, 2010 Author Share Posted July 18, 2010 well it was the air flow meter.. the carbon track had worn ou completely so i hacked up my 77 put it in soldered the little metal tabs together whammo Now I just gotta tune the meter.. Its running dangerously lean, musta been trying to correct the carbon tracks deterioration.... ran bad ass over 4 grand at 14 psi.... lol but anyway, I got the a/f ratio down to 13-1 light throttle so it runs... limped it here.. now I gotta adjust the armature to lean the idle, cruising out, and loosen the spring up some more for wot..... but its alive!!!!!!!! and yeah I had it running on a 87 z31 ecu swap, but it started to have horrible misfires started above 5 grand but now its down to 2800.... so I swapped over to the 81 ecu... slapped my wide band on it so I'll have good ratios to up the boost and find the limit.... oh 60-1 hifi turbo...... thanks for the help though guys... I was worried about it... but its alive now... Quote Link to comment Share on other sites More sharing options...
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