"96 Jimmy won't start


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Old 11-26-07, 04:13 PM
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"96 Jimmy won't start

Hi, Guys. I hope some of you Chevy guys can help me out. I've got a 1996 G.M.C. Jimmy that won't start. 4.3l v6, auto 4x4. I have good spark from the ign coil & also @ the plugs. I have 60 P.S.I fuel pressure & good flow as well. I have 5 volts referance voltage @ the M.A.P. sensor & coolant temp sensor. The fuel filter etc is only 2 months old. I scanned it with a code reader & no codes are in the computer. I don't have a tool to look @ parimater data, tho. Any ideas?? Thanks in advance, Roger
 
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Old 11-26-07, 05:49 PM
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Try turning the ignition on for 2 seconds, then off, then on again for 2 more seconds. Then try to start it. This engine needs 60-65psi just to start. Any less and it'll just crank. I have seen fuel pressure gages be off by a few psi and F up your diagnosis. By cycling the key as I described, you are priming the fuel system to build more pressure. Give it a shot just to see what happens.
 
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Old 11-26-07, 07:34 PM
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I have cycled the key several times. I have about 63-64 Lbs with the pump running & it will hold 56-58 Lbs with the key off. There is not even an offer of a fire when you are cranking it over. With that kind of pressure, would it at least start & idle?? I have lots of battery voltage, & cranking speed seems good as well. Thanks, Roger
 
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Old 11-26-07, 07:53 PM
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It should start with 60+psi. Did you check the condition of the cap and rotor yet? What happens if you crank it over for about 5 seconds with the gas pedal to the floor, letting off the pedal fully while still cranking? Does it give a hint that it wants to start?
 
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Old 11-27-07, 01:30 PM
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Thanks. The cap, rotor, plugs & wires are fairly new about 3 months ago. Replaced as a tune-up as the engine was running O.K. at that time. I have good strong spark at the dist & at the plugs as well. It wouldn't offer a start even with the throttle wide open. Do you know where I check for a pulse to the injectors?? & Why do I think they are inside the manifold?? I'm not really too familiar with G.M. as I spent 17 years @ a Ford dealer & now I work on heavy equipment. Thanks again, Roger
 
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Old 11-27-07, 04:08 PM
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Spray some carb cleaner or a bit of gas in the throttle body and be careful. Being you work around heavy equipment I am quite sure you know the risks and how to protect your self.
I think it will start and keep running when you do that. That is what I fear.
Get back to us with the results

If you already did this then please tell us the results
 
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Old 11-27-07, 04:35 PM
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Behind the throttle body on the intake, is a big connector. Pop it off and you'll be able to check for pulse while cranking the engine. Pull the fuel pump relay so you don't flood it out. I may have some wiring info on that conector, but it may be different. Let me know if you need them.
 
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Old 11-28-07, 04:11 PM
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I had a chance to pull a couple of plugs today & while they look good, the engine is flooded. I know, I should have looked earlier, but the car ran nice till it wouldn't start & unfortunatly I cant tell if I flooded it or if it was flooded. I didn't try any fuel "cus I have lots I'll try to get the rest of the plugs out. I would like it in the garage 'cus it's 10* here with snow. Too cold for a tune-up in the laneway!! Thanks, Roger
 
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Old 11-28-07, 04:20 PM
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Have you checked the ignition module? Pull a plug and check spark to make sure it is consistent and not sparatic. Also check for a good blue spark.
 
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Old 11-28-07, 05:41 PM
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Thanks, I have a strong steady spark over a spark tester set @ 3/8 to 7/16". I know the engine is flooded now, but why?? It was 40* or more the day it wouldn't start, but as I said earlier,, I may have flooded it by monkying around with it the last few days. Thanks for all the help, Roger
 
 

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