kainedogg

iTrader: (23)

Just finished an ls swap in my '68 Lemans. Car cranks but will not start. Ecm was reflashed to remove vats, however I only see 20psi on the AFPR gauge? Could this be the reason why it's not starting? What other details can I provide about the swap?

5.3/4l60e
custom harness
LS6 cam, intake and injectors
Bosch 044 External pump
Truck coils
Aeormotive Boost referenced regulator

gagliano7

First figure out why your pressure is so low. Make sure you have spark while starting motor. A lot of power sources shut off while your starting the car. Make sure there is power to pcm while starter is engaged.

kainedogg

iTrader: (23)

Thanks Gag. I have been racking my brain as to what would cause the pressure to stay at 20psi. Their power to the ecm during cranking and the pump stays on while cranking which I assume would not be the case if the ecm was off.

bczee

iTrader: (12)

20psi would be a problem. Get a pressure gauge on or in between the pump and regulator. Could be the regulator is not adjusted right ?

I would also check to make sure you have spark and also pulse at the injectors (use a noid light).

You might also check to make sure your PCM has been flashed correct to remove the VATS.. many times people have had it done or thought it was removed, but only to find out it was not.

kainedogg

iTrader: (23)

Thanks BC. I will borrow or bum a pressure gauge this weekend. I tried adjusting the regulator while cranking but it never moved past 20psi. I read that loosening the lock nut and tightening the allen screw should raise pressure, well thats a no-go at this station.

As far as the "noid" light, can I rent that anywhere or is it something I need to purchase?

I have an extra pcm that I know works since it came off my C10 ls swap. I may just swap that out first. How else would I check to see if the ecm was locked? Find someone with HPtuners?

68BBChevelle

iTrader: (12)

Another thing to check make sure u have power to the ignition relay while cranking. That jammed me up on my swap.

fbrown540

The crank position on the 68 ignition switch only feeds the starter and ignition coil (which you no longer have). You have to modify the wiring so that power is supplied to the PCM while cranking. This means you short the "run" and "start" wires together to power the PCM while cranking.

slotruk90

Which filter you runnin? Corvette filter? Lines could be crossed at the filter??

CattleAc

iTrader: (7)

A noid light is best...but, you can use a common test light also...

bczee

iTrader: (12)

Slotuk90 Stated that in the first post.

kainedogg

iTrader: (23)

This forum is awesome. Thanks guys. Turns out, I assume too much and don't test enough. Car had no gas in it. My buddy siphoned it out (for what reason I am unsure) Still does not explain why I got 20 psi. I figured that out when I pulled the hose to the regulator and there was no fuel. Added 5 gallons and adjusted the pressure to 58psi. Still no crank, why? The harness was flipped and the injector and coil connectors were on the opposite side. I was wondering why the darn ect connector could barely reach...lol. Long story short, she starts up and runs now. Just need to tackle a nasty front cover oil leak and start sourcing a GT45 turbo.

bczee

iTrader: (12)

Hey... great news !.. Don't you just have to look back and Laugh at yourself now.. I know I did on some of the goof ups I did...LOL But you must feel great now knowing you got it figured out and running..!

Maybe the gas level was just enough to prime but was sucking air along with the gas and would only be able to push to 20psi.. ??

Keep us posted on the progress now.. !

BC

BigEd_72455

iTrader: (7)

I had that issue but mine was not siphoned by a buddy, just my playing around with the truck.. I would highly recommend getting a pressure gauge and installing it permanently into your system so you can monitor it when you have issues of whatever sort. You can look at the gauge and see right away if it is or isn't the fuel pressure..

kainedogg

iTrader: (23)

Thanks guys. It does feel good to hear her start after one crank.