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-   -   Help! Rebuilt ls1 won't start (https://ls1tech.com/forums/generation-iii-internal-engine/1726391-help-rebuilt-ls1-wont-start.html)

sweetC5 May 17, 2014 09:31 PM

Help! Rebuilt ls1 won't start
 
Here's the run down, rebuilt ls1 with a small cam, fresh trans and 3000 stall. All wiring and grounds hooked up, engine cranks but will not start!! Won't even make a pop, seems like no spark or fuel. We have no codes but the check engine is on. We did have a crank position sensor code at first but we fixed it, code has not come back in days. We ran threw all the wiring and grounds again today and tried another computer with no luck still!!!

sweetC5 May 17, 2014 09:44 PM

99 trans am, I also check the pink wire to the coil pack and we are getting power.

Mgg4591 May 17, 2014 10:01 PM

Did you check for fuel pressure at the fuel rail? Also you can listen with a screw driver or stethoscope to see if the injectors are firing while cranking.

sweetC5 May 17, 2014 10:10 PM

Yes the fuel rail definetly has fuel pressure. But I don't smell gas after cranking the engine, so not sure they are even firing. Can VATS be an issue?

gMAG May 17, 2014 10:32 PM

Yes, VATS can be an issue. There have been instances where a program will show that VATS is off, when it is actually on.
Before you go that way (maybe you have no way of checking this), I would check the injectors with a noid light, and verify that they are "firing". Firing, and the actual opening, are two different things. Depending on how long the injectors had been unused, may cause them to gum up, so even though they are "firing", there may be little or no gas flowing through them.

sweetC5 May 17, 2014 11:54 PM

Thanks, I will get a noid light tomorrow and check the injectors! Getting very frustrated

gMAG May 18, 2014 09:45 PM


Originally Posted by sweetC5 (Post 18216401)
Thanks, I will get a noid light tomorrow and check the injectors! Getting very frustrated

AutoZone has a noid lamp set for "rent". If you're not familiar, you would pay for the set up front, then, when you return it, you get your money back.

slogo May 19, 2014 12:38 PM

can you use starting fluid on these engines safely?

sweetC5 May 19, 2014 03:11 PM

Checked with noid light, we have no pulse! Replaced cam sensor and it did nothing, still have no codes either.

5.0 LsX May 19, 2014 03:55 PM

map/cam sensors in back all plugged in, no bent contacts?

Exeodus May 19, 2014 04:19 PM

Have you checked the ignition relay?

sweetC5 May 19, 2014 04:26 PM

Swapped ignition relay, bypasses VATS, nothing! My scanner is not picking up rpm during crank. But I have tried two sensors and rewired half off it with a new connector. Reluctor wheel is stock and I can feel it there with my finger. Still no codes, no fuel, this is fu$king stupid!!!

sweetC5 May 19, 2014 04:28 PM

Pulled intake off again and wires seem fine, all is plugged in and have power going to them. Grounds seem to be fine as well.

sweetC5 May 19, 2014 04:51 PM

Here's a funny one. I pulled the plug off the crank sensor, guess what, no code. Does that make sense if te engine never ran?

Mgg4591 May 19, 2014 07:32 PM

Have you checked the pcm grounds? Im not sure where they are on 4th gens, but for my swap i have one ground on the back of the driver rear cylinder head, and one under the dash near where i mounted the pcm itself. The ground under my dash wasn't making good contact, so my obd2 port wouldn't connect and the car wouldn't start some times. Just something else you can rule out.

sweetC5 May 19, 2014 08:41 PM

As for grounds, I have 3 coming off the harness going into the driver cyl head. I have 3 down by the alt, one going to te alt, one frame, one on the block. Then I have the battery ground, one on the block and one to the battery, also added a ground strap engine to body!!! I checked all off them and made sure no paint or anything. Totally lost guys!!!

Hardcoresoldier May 19, 2014 08:56 PM

do NOT use starting fluid unless you want a lot more problems to deal with...

Your scanner is not showing engine RPM when cranking. If this is the case, the computer does not know the engine is turning so it will not fire the injectors or the plugs.

gMAG May 19, 2014 09:06 PM


Originally Posted by sweetC5 (Post 18219463)
Swapped ignition relay, bypasses VATS, nothing! My scanner is not picking up rpm during crank.

When you said, "bypasses VATS", does this mean that VATS has been verified as turned off, or did this mean that you have a VATS bypass module?

sweetC5 May 19, 2014 10:09 PM

I bypassed VATS by unplugging it and using the correct resistor by the ohm of the key. Car still cranked the same. Yes my scanner is not picking up RPM during crank. I also have not sprayed starting fluid! We have picked up a new plug for the crank sensor and wired that in, tried the stock sensor and the one we got from autozone and nothing. I do have 12v to the sensor but that all I know.

gMAG May 19, 2014 10:55 PM


Originally Posted by sweetC5 (Post 18220213)
I bypassed VATS by unplugging it and using the correct resistor by the ohm of the key. Car still cranked the same. Yes my scanner is not picking up RPM during crank.

I don't mean to pester you, but what does unplugging VATS, mean?
Did this mean that the BCM module is unplugged?
VATS needs either to be disabled, or, the VATS signal needs to be constant, like a VATS module.
Maybe the later F-bodies operate using a different system?


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