AL Posted September 14, 2009 Report Share Posted September 14, 2009 I just finished getting everything attached on the 91 today and went to crank it over and it wouldnt fire... I sprayed starting fluid and it fired... So I have spark... I can hear the fuel pump prime and I pushed the schrader valve and fuel squirted at me... I then used a noid light on the injectors and they did not flash, What would cause my injectors not to pulse, but leave me with spark? Edit: In the title it says its a 93 DOHC, thats because that is what I pulled the motor out of, the car however is a 91, the Manual trans is out of a 92 if it matters. Quote Link to comment Share on other sites More sharing options...
slick Posted September 14, 2009 Report Share Posted September 14, 2009 Using 93 harness and PCM? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 14, 2009 Report Share Posted September 14, 2009 A bad injector can cause all to not pulse, My old 3.4 euro lost a injector and it had the exact same symptoms you describe. to test half of the injectors, pull the plastic fuel rail cover and unplug just one injector and try starting it, move down the line and see if you get pulse back. I never did ohm out my bad injector to see what It was reading. Also, check all your fuses just in case. Quote Link to comment Share on other sites More sharing options...
AL Posted September 14, 2009 Author Report Share Posted September 14, 2009 No, I am using a 92 harness and PCM from a manual Z34 Quote Link to comment Share on other sites More sharing options...
AL Posted September 14, 2009 Author Report Share Posted September 14, 2009 For the back three injectors, I have to pull the intake tho right? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 14, 2009 Report Share Posted September 14, 2009 correct. Quote Link to comment Share on other sites More sharing options...
AL Posted September 14, 2009 Author Report Share Posted September 14, 2009 So I unplug one, Put the intake back on each time? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 14, 2009 Report Share Posted September 14, 2009 honestly if you have a known good fuel rail with injectors i'd just change the whole damn thing out. alternatively you could get a multimeter and ohm check all the injectors that *should* let you know if one is bad. Quote Link to comment Share on other sites More sharing options...
AL Posted September 14, 2009 Author Report Share Posted September 14, 2009 I thought I had a good fuel rail with good injectors lol... I will Ohm them tomorrow Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 12.4 Ohms across the front three... I havent taken the intake off yet to do the back three... The injectors are either constantly gounded or always have power and the PCM either shoots power for a sec or grounds it to make them pulse... I am thinking the constant (either power or ground) is whats not making it to the injector... My fuses are good. Quote Link to comment Share on other sites More sharing options...
BXX Posted September 15, 2009 Report Share Posted September 15, 2009 The PCM grounds them.. Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 Thanks, I will check that they have power to them Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 The injectors have power to them... The PCM is not grounding them... Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 Where does the PCM ground to? Is it one of those bolts on the bellhousing? Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 15, 2009 Report Share Posted September 15, 2009 the fsm shows it to ground within the PCM... before you rip the intake off, with the three front injectors unplugged, probe the connector for one of those injector and you should get an reading for the rear injectors, since they are wired in parrallel. that reading should be around 4-4.5 ohms, with the key off. Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 I got 2.6 all the across the front three injectors Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 15, 2009 Report Share Posted September 15, 2009 I got 2.6 all the across the front three injectors what? doing as I described? Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 I unhooked the injector, Used my ohm meter on the connector, not the injector... And it went from .3 up to 2.6 and stayed there... Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 15, 2009 Report Share Posted September 15, 2009 were only the three rear injectors hooked up? Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 no, i only took one connector off at a time... should all three front ones be off at the same time Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 All of the PCM grounds tested good... 2 sensor ground did not light the test light in the green connector... but the sensor ground in the yellow connector lit the test light... Should the other 2 sensor grounds have lit the test light? Quote Link to comment Share on other sites More sharing options...
w-bodys_are_the_best Posted September 15, 2009 Report Share Posted September 15, 2009 no, i only took one connector off at a time... should all three front ones be off at the same time I think that's what he's saying Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 With all of the front three injector connectors off at the same time, They all ohmed out to 4.2 ohms Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 15, 2009 Report Share Posted September 15, 2009 no, i only took one connector off at a time... should all three front ones be off at the same time yes. assume a parallel circuit, and the injectors all have the same observed ohms of 12.4. if you can't get to three injectors, but you can unplug the other three, you are measuring the summed up total of the injectors (3 injectors) (12.4+12.4+12.4) / 3 37.2 / 3 12.4 ohms= ------------------------- = ----------- = ------- = 4.13 3 3 3 (5 injectors) (12.4+12.4+12.4+12.4+12.4) / 5 62 / 5 12.4 ohms= ------------------------------------------ = ---------- = ------- = 2.48 5 5 5 they are in parallel, and your measurement of 4.2 ohms for 3, or 2.6 ohms for 5 is consistent. your issue is elsewhere. Quote Link to comment Share on other sites More sharing options...
AL Posted September 15, 2009 Author Report Share Posted September 15, 2009 We pulled the intake off and the other three injectors ohmed out to 12.4 12.4 and 12.5... Quote Link to comment Share on other sites More sharing options...
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