Car will not start (Very little spark)
07-23-2011, 02:44 PM
#1
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Car will not start (Very little spark) Good afternoon LS1 Tech professionals. As the title states I am try to turn my car over and I am not getting a whole lot of spark from the test I did by holding a plug in a wire out and grounding it to check spark. The plugs smell of fuel higher than I think they should be. And a little wet as well. Here is what we got... I am running a 408 LQ9 in an LT1 car. We are using the stock return line from the factory lines. One of my thoughts was to see how much fuel pressure is needed at the rail with 42lb injectors with running a return. I posted that question in the fuel section (no replies yet). We have checked all the wiring and sensors. Everything is getting 11.3v all they way up to the coil harness plug-in. I have added three extra grounds, and changed the connections from the harness to the battery. I am really at a loss of why the car will not turn over. When we cranked it, it did back fire a few times but no start. 
Any help would be appreciated. Thanks guys.
John
Any help would be appreciated. Thanks guys.John
07-25-2011, 07:17 AM
#3
'We are using the stock return line from the factory lines. One of my thoughts was to see how much fuel pressure is needed at the rail with 42lb injectors with running a return."
The fp should be set at whatever you have in the tune..If the injs are 42pph @ 3 bar, then set the reg @ that value. Same with the injs @ 4 bar.
@ 11volts, U R most likely getting some poor ign performance.
A fully charged batt should be 13+ volts.
R U sure the harness's are plugged in correctly?
Injs been sitting for an extended period?
The fp should be set at whatever you have in the tune..If the injs are 42pph @ 3 bar, then set the reg @ that value. Same with the injs @ 4 bar.
@ 11volts, U R most likely getting some poor ign performance.
A fully charged batt should be 13+ volts.
R U sure the harness's are plugged in correctly?
Injs been sitting for an extended period?
07-25-2011, 01:05 PM
#4
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Thanks. I was kinda thinking the same thing about lowering the rail pressure. Yes, the injectors have been sitting for a while now. Do I need new ones? Thanks for the input. Harness is plugged in properly as well.
07-25-2011, 08:02 PM
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07-25-2011, 09:54 PM
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I will check that. Did ya happen to see my last post about the oil pressure sensor? Also, after about 3 cranks the voltage goes from 13.1 to 12.3. Any thoughts on that one? Thanks for the input.
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07-26-2011, 06:06 AM
#8
I haven't seen an LS PCM that needs to see oil pressure sensor output in order to run the engine. Most of them don't even monitor oil pressure, the sensor is wired to the dash gauge.
07-26-2011, 06:19 PM
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07-26-2011, 09:43 PM
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He said it worked for him. And I have been looking at some old posts about this issue as well. A couple of other people have said the same thing. I am going to at least try this tomorrow. It will at least eliminate another idea for trouble shooting. Thanks for the input guys. This is really aggravating.
07-27-2011, 07:49 AM
#16
?? As I said before, IF the injs are 42#'s at 3 bar,[43.5psi], AND you have that flow rate in the .tun, then you HAVE to set the reg at 3 bar...IF the calculations for inj flow were made using 4 bars,[58psi], then the reg HAS to be set accordingly...
As for the injs "sitting for a while"...If they have old/no fuel in them, there's a chance they are stuck closed...Cleaning may correct this problem..May not, depending on how long/how much crap in them/how they were stored.
IF the reg is vac referenced, the IFR in the .tun has to be set up w/ a single value. If the reg is atmosphere referenced, the IFR has to be on a slope...
