new here need help PLEASE!!!!!!!!

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Mar 11, 2007 | 04:11 PM

ktrim

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5.7 vortec wont start help!!

the guys at teamchevelle sent me here said yoy guys would probably have this figured out in a matter of minutes

The problem is on a 1999 yukon 5.7 vortech. My father in law drove it home from work at 7:00am, when he went to leave again at 6:00 pm it would turn over but would not start. checked the fuel pressure it was 48lbs with key on and dropped to 25-30 while cranking, I replaced the fuel pump. It now has 58-60 with key on and 65 while cranking. Still will not start. replaced the cap,rotor,wires, plugs, and module. have a strong spark at all cylinders but still wont start. We tried shooting som starting fluid down the throttle body and got a back fire and some pops out the exhaust but as before no start. anyone have any ideas or suggestions. I am at a loss and need this thing fixed asap

Thanks

Last edited by ktrim; Mar 11, 2007 at 04:54 PM.

Mar 11, 2007 | 11:40 PM

BLOWNBLUEZ06

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From: Forney, Texas

Three things run an engine. Fuel, compression, and ignition. If you tested the ignition, and you tested the fuel pressure, make sure you have compression. Just pull a plug out and put your finger in the hole and crank it if you don't have a compression gauge. If it blows air out, then you have some compression. This is really only to see if your timing set didn't break. If you can see down in the valve cover that the rockers are moving then that will suffice as well. You tested fuel pressure, but that doesn't mean that fuel is getting in to the engine. You need to make sure that the injectors are getting pulsed. Check your fuel fuses there is usually more than 1 fuse and make sure you check the ones under the hood too. If you have a volt meter, the computer should have voltage on the injector with the key on and pulse ground to open it. Do not use a high current test light. Use either a volt meter or an led based test light to test the voltage to the injectors.

Mar 12, 2007 | 05:26 AM

ktrim

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It has good compression, and the rocker arms are moving so the chain isn't broken. I just read on another site about the exact same problem on a tahoe. That guy ended up bringing it to dealer. Dealer said the stock security had wiged out and locked out the injectors. after they reset the security it was ok. According to him he never had a security light turn on the dash (mine doesnt come on either). Ive been trying to find out how to reset the security to eliminate that as a problem. Does anyone know how?

Mar 12, 2007 | 05:48 AM

Kage

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From: C.C. Tx.

Have you checked fuel pump fuse in the eng. bay?? I have a 02 Tahoe Z71 5.3, had a bad fuel pump fuse while back had the same prob. yours does, cracked but wouldn't start up.

Check it out, it might be it..