put a brand new jasper 5.3 in my girlfriends truck
cranks over but wont start tach doesn't move I know there is some crank relearn that must be done at the dealer but just to see I checked for spark and i got nothing
I was under the impression these trucks would start but throw a code for the crank relearn

and I checked the crank sensor is plugged in
can anyone help me out thanks

John

 

Did you connect up the grounds on the back of the block?

 

A Crank Re-Learn has nothing to do with it not starting. You won't get a code or have an issue until after it is running.

You must have Spark and fuel Along with compression in order for it to run.

Assuming that it was properly rebuilt and installed correctly, That would leave spark and fuel.

You mentioned a No Spark condition. As mentioned you need to make sure all the grounds are connected to the engine and chassis. There is a couple of grounds on the engine harness that connects to the back of the block behind the intake. Also there is a ground strap at the lower front of the block that attaches to the frame rail. If these are not connected it could cause a similar issue. Also give the coil connectors another look and make sure there connected properly. If everything else checks out then take a look at the dash when your cranking the engine. Do you see a security light flashing??? If so it could be the VATS. The Vehicle Anti Theft System could also cut the spark signal as well.

HTH

 

yea I actually realized I had that small ground in the main harness into the head not the block, figured it wouldn't ground through aluminum so I put it into the block still wont start

everything's plugged in....

 

power and ground to coils but no spark has to be a sensor and or computer issue guna borrow a good scan tool and attempt a crank relearn or else its goin on a trailer and to the dealer

 

The engine has to physically be running in order to Preform a crank relearn.

It might be the Anti Theft System. It will store a code for the anti theft if that's the issue.

 

did you change the computer also? or is it the same computer that was in the truck?

if you didnt it should crank anyway, doesnt matter which motor is in there as long as its the same computer. double check grounds, theres also a ground that goes to the power streering box to frame also theres one trapped to the inside of front fender. ( if not mistaken)

also is this a long block or a short block and you put the heads on? if you did the heads what size push rods did you use? try a compression test to rule out no compression.

personally if you didnt change computers and its not wanting to start and just turning over it could be the computer is trying to learn the variables in the tune, i had this issue when i put a 6.0 in place of a 5.3 only thing i changed was the motor nothing else and i knew everything was hooked up, Ben and i knew things were right it just took turning the motor over alot for it finally fired off and started running

 

Try the crank sensor...no sig no fire...double check everything even oil!

 

good point on the crank sensor

 

Lol ... learned my lesson