Ok so Ive been reading everybody else's posts and have an idea of whats wrong, but still cant figure it out. I just replaced the 5.3 with a 6.0 and wired everything up. I have a nelson tune and Im getting the engine to trun over (slowly) but not getting spark or fuel at KEY ON. the only way im able to get fuel is by manually priming the fuel pump on the fuse block. Ive tried the security relean and i thought i fixed it since the security light goes out....but it sill wont start. Any ideas??? please help

 

Fuel pump relay?

 

try the security relearn again

 

did you do the relearn procedure correctly, if everything else is in order it should fire up on the 4th try. If the Security Relearn procedure is needed, it should take like 40-45 minutes to complete and start up on the 4th start attempt.

You said you THOUGHT you fixed it since the light goes out, if the truck doesn't start I would make sure and do the whole relearn procedure again.

step 1 attempt to start vehicle. If it starts up no relearn is needed. If it does not start or if it immediately dies, then the relearn is needed.

step 2 Leave key in run position for 10-12mins (until security light shuts off). Make sure that no accessories are on and that your headlights are switched to the OFF position.

step 3 Remove the key from the ignition for 45 seconds.

Step 4 repeat steps 1-3 three times. On the FOURTH start attempt, the vehicle should start and the relearn is complete.



Hopefully it isn't some other issue but it does sound like you did not do the relearn correctly. I would try to do it again first..

 

miss any ground wires? like the one on the back of the motor, driver's side? Small wire, easy to miss, **** won't start without it.

 

I'll check the grounds again, the fuel pump relay may have two problems. 1. there is one pin that is suppossed to be hot at all times (according to the wiring diagram) and isnt. What would cause that? 2. the fuel pump relay is loose on the fuse block. Also i called nelson and was able to confirm that the V.A.T.S. ( anti-theft) was deleted off the tune. So i agree it wouldnt hurt to do the re learn again, but he said as long as the light goes out its fine. Any other ideas? I'll give all that a try

 

I am not sure, been awhile since I played with those relays...aren't most of them the same? If so pull a non-vital one and swap with the fuel pump relay.

As far as a constant hot, possibly but the relay will send the voltage to the wire that's not hot (that's where the constant hot it, on the point of the relay). Make yourself a test light. 12v DC bulb with two long leads, each lead with an alligator clip. One clip on ground and the other on the wire that should be positive but you have your doubts about. Always test bulb on know working source before testing.

You can even remove the clips and use small gauge wire and jam the wire in the relay tabs. The lamp will tell you everything.

(I like the lamp technique when I am doing a lot of key on key off scenarios, no need to look at the tester, lamp gives it away)

 

bump for new ideas. Checked it with a test light still no power to the relays, even switched relays thinking maybe it was just a bad one. Didnt see any grounds disconnected. Any body got any more ideas?

 

sounds like a bad ground wire, check to make sure both ground wires are on the back of the block, there should be a ground on both sides of the block