68_firechicken

iTrader: (1)

I posted this same thread last week and executed all of the suggestions i received and nothing. I checked the ign. and power wires on the coils. Everything checks good. I checked PCM power wires while it was turning over it dropped to about 9.5 volts. I thought that was ok. Changed the injectors and it still won't run. it back fired through the intake a little. That was the extent of the excitement.

I am thinking it is mechanical now. I am still a little green to these motors. I just need a little input on what to look for.

nos487

iTrader: (4)

Maybe just start with the basics. Make sure it has good compression, fire and fuel. Have you pulled out the injectors and seen if they are spraying fuel?

91sonomast

Do you have the correct reluctor wheel and tune in the PCM? Backfiring through intake sounds like a timing problem. If a cam was installed was it installed properly?

68_firechicken

iTrader: (1)

It is bone stock would the voltage drop with ign have anything to do with it? I was going to take the injector ran out of time. It's just going to make a mess. haha!

91sonomast

9.5 is within acceptable GM limits for voltage drop on crank, anything less than 9volts is when GM says you could experience issues, so I wouldn't think that was it. Throw a battery charger on it, crank and check your voltage. It's possible it could be an issue, stranger things have happened.

psiconversion

iTrader: (5)

If you spray starter fluid in the throttle body will it start?

Do you have the correct tune in the car?

Jon
PSI

68_firechicken

iTrader: (1)

I tried spraying starter fluid in the throttle body and that's when it back fired. I got the wiring harness and the PCM form chevythunder.com. I assume that the tune is good I gave the guy all my specs. I think he has a pretty good rep. I hooked the PCM up to another car and it fired right up. I am pulling the engine this weekend. The guy I got the engine from had dropped it on the oil pan. The bottom of the pan was cracked to ****. I took the oil pan off and inspected everything. Everything looked ok but then again I didnt think about the The pick up on the CPS. I pulled the CPS out and it was good. Idk just pissing in the wind right know.

Adam123

iTrader: (1)

Check the keyed ign. wire to ecm. Lets computer know that when key is on.

Adam123

iTrader: (1)

On blue connector wire number 19 pink wire

psiconversion

iTrader: (5)

Check the TPS voltage or % if you have a scanner.

Jon
PSI

91sonomast

Are you getting adequate fuel up there, correct?

68_firechicken

iTrader: (1)

Here is a thought. I don't have a MAF senser hooked up yet could that be the reason it will not run?

salemetro

iTrader: (5)

Entirely possible. I'd tie up all the loose ends FIRST, then try to fire it up. Much easier to diagnose that way.

aknovaman

iTrader: (7)

Yes, unless you have the PCM file set up for SD mode it will not start.

waterbug1999

iTrader: (3)

what does it do when u try to crank it over?

ad53030

Can try to get a noid test light and make sure that the computer is sending a signal to the injector. That way you can rule out that the programming was done correctly. Can rent them at local auto parts stores. Just a thought. I had an issue that eventually turned out to be a programming error involving the VATS (depending on what year your 5.3 is).

68_firechicken

iTrader: (1)

The motor cranks over. It kinda sputters but does not run

68_firechicken

iTrader: (1)

I did the noid test it lit up

waterbug1999

iTrader: (3)

as in popping?

Goodies Speed Shop

Can be a ground issue also... Motor grounded to frame?

Agree with salemetro about the MAF....