2000 gmc 4.3 not starting

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msbarrett72
Posts: 2
Joined: Wed Sep 11, 2013 9:02 am

2000 gmc 4.3 not starting

Unread post by msbarrett72 » Wed Sep 11, 2013 9:14 am

I have a 2000 sierra 2wd 4.3 that will not start. you can hear the fuel pump cut on and have 60psi at the valve. It seems like the signal for the injectors is not being sent. I have replaced the following,distributor,fuel spider, crank sensor twice, icm and coil , oil pressure switch, fuel pump and it will run on spray with no problem. after replacing the fuel pump it fired right up and ran for a good amount of time while i put the truck bed back on. cut it off a few times and fired right up. went to drive up the street to get some gas and it cut off. Now it will not run except on spray and no codes. also tried resetting the computer twice no help. I don't have the money to keep throwing at it .Any ideas would be great. Thanks

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carriedi
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Joined: Wed Apr 10, 2013 12:42 pm

Re: 2000 gmc 4.3 not starting

Unread post by carriedi » Thu Sep 12, 2013 10:28 am

do you have a security light coming on? You may have your theft system turning off the fuel injector pulse.
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msbarrett72
Posts: 2
Joined: Wed Sep 11, 2013 9:02 am

Re: 2000 gmc 4.3 not starting

Unread post by msbarrett72 » Thu Sep 12, 2013 11:16 am

no theft system on this truck, I got a ecm from a junkyard yesterday still no help. It has to be a switch or sensor Im missing.it runs fine on spray every time. thank you for taking your time to reply.

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carriedi
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Re: 2000 gmc 4.3 not starting

Unread post by carriedi » Thu Sep 12, 2013 5:03 pm

ok, you are going to need to do some basic tests to see what is going on. Have you scanned for codes? Can you use a scanner to look at the data stream and see it it shows engine rpm while cranking? Since we know it will start with fuel added manually spark should be ok. Do you have an inductive amp probe you can use on the injector wiring to see if the pcm is sending out an injector pulse? do you have an injector pulse when it won't start? Do you have power to the fuses pcm1, INJ1, INJ2 in the underhood junction block while cranking? (INJ1 and INJ2 may be marked INJ A and INJ B) they should be hot with key in run or start.
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