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97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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E.B.
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Oct 9, 2012, 4:29 PM
Post #1 of 28
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97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Cylinders no 2&4 dumping fuel. Wash down and compression tests have been done, all came back good. Lower intake pulled gaskets good, tried new injectors, still the same. Fuel pressure tests were good. Any thoughts?
(This post was edited by E.B. on Oct 16, 2012, 4:21 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 9, 2012, 5:22 PM
Post #2 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Is it holding rest pressure?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 5:24 PM
Post #3 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Sorry not a mechanic, I have it at the shop now. What is rest pressure?
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 5:27 PM
Post #4 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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It means, does it maintain correct fuel pressure for a period of time after the key is shut off or does it drop off considerably in the first 5 minutes?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 5:29 PM
Post #5 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Talking to mechanic and he said it holds good pressure.
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 5:36 PM
Post #6 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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That means you don't have a leak so now you have to look at injector controls and wiring. You can test each individual injector trigger with a noid light to see if any are shorted to ground which would keep the injector open all the time. This would also show up as a fuel pressure drop when the key is on, engine off.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 5:40 PM
Post #7 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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So if it is going to ground then the injector would be open all the time causing the overfueling?
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 5:43 PM
Post #8 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Yep. The injector receives power all the time when the key is on and the computer pulses the ground to fire it off. The amount of ground time determines the "on" time for the injector called the "pulse width"
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 5:47 PM
Post #9 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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The mechanic told me his scan tool is able to fire each injector, and he knows that they are all functioning.
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 5:49 PM
Post #10 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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OK, if you say so. You just eliminated all possible cause of fuel washdown so apparently you don't have a problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 5:55 PM
Post #11 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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I had just called him relaying messages back and forth. Is that something you have never heard of before?
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E.B.
User
Oct 9, 2012, 5:58 PM
Post #12 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Could it be a head problem? Or are you convinced it is an injector problem?
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 5:59 PM
Post #13 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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As I just told you, either your test results are tainted or incorrect or you don't have a problem at all because according you you, it passed all the tests so i'm pretty much done here. Fuel can only get into the cylinders either through the injectors or around them and you supposedly eliminated both.
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E.B.
User
Oct 9, 2012, 6:03 PM
Post #14 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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That makes sense, I know there is a problem. Fuel in the oil, and popping out the exhaust. The only problem I have had with the motor is intakes gaskets in the past, been very dependable.
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 6:04 PM
Post #15 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Check engine light on? What are the code numbers?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 6:08 PM
Post #16 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Waiting on a reply from the mechanic.
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E.B.
User
Oct 9, 2012, 6:32 PM
Post #17 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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The only code that came up was a p0300.
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nickwarner
Veteran
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Oct 9, 2012, 6:37 PM
Post #18 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Thats a random cylinder misfire. Has he looked at the misfire counters?
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E.B.
User
Oct 9, 2012, 6:40 PM
Post #19 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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That I do not know, last time I talked to him, he said the only thing that did not check out was that bank of the engine was runnin rich.
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Hammer Time
Ultimate Carjunky
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Oct 9, 2012, 6:49 PM
Post #20 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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I don't know how he's concluding that because there are no rich codes so the computer isn't seeing it.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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E.B.
User
Oct 9, 2012, 6:52 PM
Post #21 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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That I cannot answer.
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Discretesignals
Ultimate Carjunky
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Oct 10, 2012, 8:15 AM
Post #22 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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Just curious, but how did you determine cylinders 2 and 4 were dumping fuel?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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E.B.
User
Oct 10, 2012, 6:28 PM
Post #23 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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No 2&4 plugs were wet with gas, the rest were dry.
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E.B.
User
Oct 10, 2012, 6:31 PM
Post #24 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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I think we have it narrowed down to crossfire in the cap. Frustrated spending a fair amount of money for a simple fix.
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Discretesignals
Ultimate Carjunky
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Oct 10, 2012, 6:59 PM
Post #25 of 28
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Re: 97 gmc sierra 1500 5.7 cylinders 2&4 dumping fuel
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It wasn't dumping fuel. It was injecting fuel, but because of no spark your plugs were wet. I don't think I have seen a CMFI injector hang open as of yet. It would be even rarer for two injectors to do that, but you never know what you'll run into. Glad to see you figured it out.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Oct 10, 2012, 7:00 PM)
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