Mechanics

ROUGH IDLE EXCESSIVE CRANKING TO START

2002 GMC Sierra

Replaced fuel pump, 130K 5.3L 2WD, Opinions have led me to a possible O2 sensor failure? Idles rough if it does start and the only way I have found to keep it running for a few seconds is to press accelerator to floor in which case it revs up then back down and dies. Also, changed ffuel filter at time of fuel pump change. If it is the first time I have tried to start it for the day, it will start and idle rough, then begin to die and the only way I have gotten it to run for approximately 10-15 seconds is by full throttle. The engine will respond to the throttle somewhat and then back down and die. No trouble light or check engine lights, or at least not enough run time for me to see them. I have experimented with continuous cranking until it starts, average of 30 seconds before starting, but still does the same and dies. Checked OBD with code reader from Oreillys and it says no codes stored, but readiness monitors are incomplete including catalyst, evap. System, O2 sensor and O2 sensor heater not completed in their respective checks. Thank you for any suggestions or input.
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Outhoo
July 15, 2007.



Im posting this reply for others to utilize in there own troubleshooting and will continue to update for FREE, since no one has any input, I do not recommend anyone offering donations to something that isn't of help/use to people out there.

Replaced all four O2 sensors with same activity present as described in my previous post.

Tiny
Outhoo
Jul 20, 2007.
Sounds like ur fuel sytem is not holding residual pressure. If u cycle ur key which mean the fuel pump primed the system with pressure. Of course it will start.
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Tiny
Kin chan
Jul 20, 2007.
When did this problem start? Did you go out to start the truck and it just wouldn't start? Did it die on you going down the road? What did it do before you replaced the fuel pump?

I have seen some of these that have the injectors just dumping major amounts of fuel. Check the oil and see if it smell like it is full of fuel.

Those tests that the PCM runs through haven't ran because the perimiters that are required have not been met. It dosen't mean that those sensors or curcuits are your problem.

Cly

Tiny
Cly
Jul 20, 2007.
Thanks for your attention Cly, the problem came about after the truck had set without being started for approximatly 4 months. At first it started and ran fine, then it would not start and when it would, it would idle extremely low and die unless I accelerated, only to last for a few seconds, then die. There does not seem to be any pattern of starting or inability to start. I intend on pulling the injectors to see if they are clogged. It seems as though the engine is being starved for fuel rather than a sensor failure. Before parking the vehicle for the period of time mentioned, it was idling rather inconsistently. I do not have any injector experience, but should have by the time I'm finished. The fuel pump nor the O2 sensors were the problem, but with the mileage being over 100K, I don't think it was a bad move to replace either. I don't think I have bad fuel, because I fuel at the same station daily on my 07 GMC and have been for the last year without any problems. The oil, I changed before the problem came about and checked for the fuel smell, without positive results. Thanks again for your reply.

I have seen some of these that have the injectors just dumping major amounts of fuel. Check the oil and see if it smell like it is full of fuel.

Those tests that the PCM runs through haven't ran because the perimiters that are required have not been met. It dosen't mean that those sensors or curcuits are your problem.

Cly[/quote]

Tiny
Outhoo
Jul 21, 2007.
[/quote]

Residual Fuel Pressure Test: As recommended by Kin Chan

When the pump is turned off or stops running, the system should hold residual pressure for several minutes (look up the specs to see how much pressure drop is allowed over a given period of time). If pressure drops quickly, the vehicle may have a leaky fuel line, a leaky fuel pump check valve, a leaky fuel pressure regulator or one or more leaky fuel injectors. Low residual fuel pressure can cause hard starting and vapor lock during hot weather.

Also check the coolant temperature sensor. This one here is like the choke on a carb.

Rasmataz
Jul 21, 2007.
Were did the truck sit? Outside in the weather or in a climate controled area?

Is it possable that the fuel quality has deteareated over that time?

Maybe it has goten some water in it?

Could it be that a varmint has been chewing on some wires somewhere?

Have you tried to spray carb clearner into the intake while someone starts the truck and see if it runs while the spray is being introduced into the intake?

Problems like these are hard to solve over the internet.I will try my best to help you.

Cly

Tiny
Cly
Jul 21, 2007.
I found your responses extremely attached to the statements I made concerning the problems I was having brought on by negative attention to your website. Do you only give feedback to those who are in need or do you actually care about the people who have legitimate problems? I don't see this site as a help to the average JOE if you will to be a tool for fixing problems. This site is merely a postboard for opinions and anyone can post an opinion on the web. If you want a donation or feedback review, then be helpful and courteous. Your responses to my postings only lead me to believe that this is a site looking to profit on others ignorance of the aspect of the feild of general maintenance on vehicles. I will notify anyone and everyone I know to stear clear of such shams of information that this site offers. The simple truth is there is nothing on this site that is of help to me or anyone else who with a short amount of time can research on there own. Thank you for nothing and good luck in your endeavors.

Tiny
Outhoo
Jul 30, 2007.
OutHoo-

You end your first post with “Thank you for any suggestions or input”. Did you really mean that?
Obviously not. Do you realize how many posts go unanswered because of the shear volume we get? I assure you we don’t get rich. On average, I earn less than a few dollars an hour from donations. Essentially it pays for my Internet costs and a chance to reward my wife with dinner for putting up with the ridiculous time I spend helping other folks. Yeah it is still a source of motivation, but not the biggest. I get pure satisfaction when I solve someone else’s problem…over the net…when a shop couldn’t do it…that has the tools and cars at their disposal. Their (the proper spelling in this context) appreciation is a driving force. I also have the opportunity to learn here, from other contributors such as the ones that tried to help but you so arrogantly dispatched. You weren’t looking for any “suggestions or input” were you? You were looking for the magic bullet that would solve your problem, weren’t you? You chose to replace all of your 02 sensors instead of working with these guys that were willing to help.I hope you blasted those folks also. Who were those folks anyways?

I answer the non-donation posts more often than the donations posts. Yes they get priority when I feel I can help.

I find it rather amusing how some folks such as yourself feel that you have the right to be able to abuse anyone in your path should you choose to. You expect “helpful and courteous” treatment, but dish out quite the opposite. In the auto repair industry as in other businesses we perform a technique called “Weeding”. There is NO need to have to put up with folks that display your kind of abusive antics. Like the hard work that goes into a garden, bad weeds like you are plucked out and banished. You are clearly a time waster, stealing precious time away from folks that are willing to work through their problems with us instead of interacting.
In closing, please do tell everyone about our site. I find anyone with a little intelligence will consider the sources when listening to another speak. People don’t like to confront a raging bull such as yourself, but I guarantee you that they have an opinion that does not coincide with yours. Your blabbering ironically will serve to promote our site. Ironic huh?

U okay service writer?. I guess everywhere I go I really draw opiinions. Look up any spec on any 96' cars from any manufactures thats runing on the road in united states. On all obd2.O2 sensor don't come on at the very least 30 sec after start up. ON ALL CARS. Either ECM lost memory( good possibility w/lots or incomplete monitor) or fuel system has leak which is open loops cuz no start n of course the ECM store no codes.N this guy according to his thinkin (with no creditible, reliable info or resources) outta his own fantasy think the problem is the O2 sensor. What he eXpect this site is to turn a person who can't even fix an OBD1 car without a shred of basic concept & training on automotive internal combustion engine performance
n make him overnite a mechanic. Heh. Hah !.I guess I have to close my shop down if theres such site exist. Oh oh oh. Why don't we try these too. Lets cancel all the doctors. Cuz theres gotta be some sites that will offer help to circumvent yrs of trainin & knowledge
of medicine practice. So people can fix their body. SOMEBODY WAKE ME UP PLEASE!.I think I am still in a dream !. Heh heh

ONE MORE THING. CHK ME OUT HERE.I DON'T GET PAY BY THIS SITE. EVEN THOUGH I WAS QUALIFED.I ONLY DIAGNOSE N ANSWER CHALLENGING PROBLEMS.I ALWAYS ADVOCATE DIAGNOSTIC. TO TURN A NOVICE PLAIN JANE PERSON OVER NITE TO A PROFESSIONAL MECHANIC SO THEY CAN CIRCUMVENT FREE MARKET DRIVEN PRICE PROFESSIONAL SERVICE. THATS THE ABILITY OF GOD NOT HUMAN NOR US !. WHY IN THE WORLD U THINK GM DEALER OR ANY PROFESSIONAL DO AN ENGINE PERFORMANCE DIAGNOSTIC USING A TECH2 SCANNER WHICH COST THOUSANDS OF $$$ INSTEAD OF USING A CALCULATOR CODE READER WHICH U CAN BUY IT FROM O'REILLY, AUTO ZONE FOR LESS THAN A HUNDRED. THEY MUST HATE THEIR $$$$. HEH HEH HEH HEH. KEEP ON DREAMING

Tiny
Kin chan
Jul 30, 2007.
I love the reply Service Writer. I couldn't have said it any better myself.

Only thing I can say to outhoo now is.

Thanks for stop'in by.

Cly

Tiny
Cly
Jul 30, 2007.
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