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running lean on GMC van 6.0


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john M2
User

Jul 25, 2012, 5:41 PM

Post #1 of 25 (3414 views)
running lean on GMC van 6.0 Sign In

okay, 2004 gmc savana 3500. 6.0 V8, fuel inj. 95,000 miles but more hours on engine than miles as it is used to run a carpet cleaning blower. problem was it died and would not fire on my buddy as he was coming home. turned over great, no start. after tow to my house we tried it. it started but ran real rough. i could smell raw gas fumes from tail pipe. i changed plug wires and runs pretty good now. but, it starts hard. much cranking and slowly starts to fire on all cylinders. when it does get going it runs smooth. if you hit the gas you can hear almost what sounds like a sucking sound for just a second, and the engine hesitates. then it goes just fine. under a load it seems less powerful than it should be. i put a new MAF sensor on it and that helped a little. i checked all vacuum lines and did a vacuum test and it said it had perfect vacuum. i had the codes read at the auot parts store and came back with lean on both banks, PO171 &PO174. i am going to check the air intake tubes again. they seem real tight, but maybe a small leak. what next? fuel pressure? i don`t have a tester for that. i can`t find the fuel filter, people say it is under the driverside seat inside the frame rail. i see the lines but no filter. there is a big black box rith next to the gas tank, could it be in there? fuel regulator sensor? fuel pump? but what is that sucking noise???? his other van has a 5.7 in it and it does not make that noise. any help or ideas i`ll give it a try. thanks in advance.


Hammer Time
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Jul 25, 2012, 5:43 PM

Post #2 of 25 (3404 views)
Re: running lean on GMC van 6.0 Sign In

Fuel pressure is the first thing I would be testing.



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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.



john M2
User

Jul 25, 2012, 5:45 PM

Post #3 of 25 (3399 views)
Re: running lean on GMC van 6.0 Sign In

what is the best tester for this, that a regular guy could afford. i have done a lot of stuff over the years on older cars and trucks, (rebuilt engines, rear ends, Etc...) but these new ones with all the sensors and computers makes it harder for me.


Discretesignals
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Jul 25, 2012, 5:47 PM

Post #4 of 25 (3394 views)
Re: running lean on GMC van 6.0 Sign In

You might have to borrow or rent a fuel pressure gauge to see what the fuel pressure actually is when this is going on. It would also be good to make sure the pressure holds when the pump is off.

edit: HT gotcha





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 Jul 25, 2012, 5:48 PM)


john M2
User

Jul 25, 2012, 6:12 PM

Post #5 of 25 (3369 views)
Re: running lean on GMC van 6.0 Sign In

i was reading and from what i found you can check fuel consumption by running checking some things with the scanner while the vehicle is running. i might get a scanner. i can use it on my cars too in case i need it. what might be a practical one to get that does more than just read codes? thanks


nickwarner
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Jul 25, 2012, 6:30 PM

Post #6 of 25 (3364 views)
Re: running lean on GMC van 6.0 Sign In

I would assure you it would be cheaper to buy the fuel pressure gauge than a scanner with live data capability. If you have a hard time with computer controls you wouldn't know what you're seeing on the PID list anyhow. Not trying to be condescending, but don't want to see you blow money on a tool you don't understand the readings of. These engine control systems require a lot of training in theory of operation just to make some sense of what the datastream should look like.


Discretesignals
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Jul 25, 2012, 6:39 PM

Post #7 of 25 (3361 views)
Re: running lean on GMC van 6.0 Sign In

Scanner isn't going to tell you what the fuel pressure is anyhow.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


john M2
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Jul 25, 2012, 8:10 PM

Post #8 of 25 (3339 views)
Re: running lean on GMC van 6.0 Sign In

that`s what i was thinking on the scanner and what it can actually do. but will low fuel pressure cause the sound that i`m hearing? i would compare this sound to a leaking intake manifold gasket. any idea`s on that?


Discretesignals
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Jul 26, 2012, 3:08 AM

Post #9 of 25 (3329 views)
Re: running lean on GMC van 6.0 Sign In

If you haven't found any vacuum leaks, it could be the sound of the air rushing into the plastic intake because the IAC is opening more than it should due to the computer trying to keep the engine running as it is trying to stall out. You still need to verify fuel pressure.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


john M2
User

Jul 26, 2012, 6:21 AM

Post #10 of 25 (3317 views)
Re: running lean on GMC van 6.0 Sign In

makes sense and i thought the same thing, but can`t see anything on this van. this one you have to take the passenger seat out to get the engine cover completely off. i will see what i can do on the fuel supply in the next couple days. thanks everyone. i will report back when i can.


Hammer Time
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Jul 26, 2012, 7:06 AM

Post #11 of 25 (3314 views)
Re: running lean on GMC van 6.0 Sign In

I'm betting that engine cover will come out of there if those seats are OEM.



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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.



john M2
User

Jul 26, 2012, 7:20 AM

Post #12 of 25 (3306 views)
Re: running lean on GMC van 6.0 Sign In

nope, already have it out. a few other people said the seat has to come out on this 2004. they were right. his other van that has the 5.7 has a shorter cover and can come out without removing the seat. just one of those things.


john M2
User

Jul 27, 2012, 6:29 PM

Post #13 of 25 (3281 views)
Re: running lean on GMC van 6.0 Sign In

follow up so far. i haven`t gotten a fuel pressure tester yet, but i took the whole air intake housing off and inspected for any cracks or leaks. i had the battery unhooked too hoping to reset the MAF sensor and computer at the same time in case i didn`t leave it off long enough last time. everything was good, but was missing a bolt for the air cleaner housing to the MAF housing. put in another bolt made sure all other fittings were put together correctly. started it up and it ran terrible, let it start kind of setting its self and then it cleared up like it`s supposed to. drove it a bit, still hesitates and has that "whisp" sound when hitting the gas. if you apply light throttle it goes fine, but if you punch it it will bog and hesitate. it even back fired 1 time when i punched the gas at about 35. almost like a timing problem. even though the spark plugs seem good and i cleaned and gaped them could they be a problem still. they are those stupid iridium plugs so you have to be real careful with those when gaping. when my neighbor down the road is home i will see if he has a fuel tester.


john M2
User

Jul 27, 2012, 6:37 PM

Post #14 of 25 (3279 views)
Re: running lean on GMC van 6.0 Sign In

oh and when i went to start it, the check engine light was off and stayed off the whole time.
it was on all the other times before today.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 27, 2012, 7:03 PM

Post #15 of 25 (3275 views)
Re: running lean on GMC van 6.0 Sign In

I'm still waiting to hear what the fuel pressure is.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



john M2
User

Jul 27, 2012, 7:10 PM

Post #16 of 25 (3269 views)
Re: running lean on GMC van 6.0 Sign In

i have a big bunch of jobs to do so it may be a few days before i can test it. i might order one online so i have one around here when i need it. i have about every tool i need for almost anything, and have made a few instead of buying them, but i can`t find my fuel tester. i had one once but knowing me i lent it to someone and never got it back. i did find my timing light which i forgot i had too.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 27, 2012, 7:12 PM

Post #17 of 25 (3264 views)
Re: running lean on GMC van 6.0 Sign In

LOL, Timing light is obsolete. You won't need that any more.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



john M2
User

Jul 27, 2012, 7:14 PM

Post #18 of 25 (3261 views)
Re: running lean on GMC van 6.0 Sign In

that`s why i forgot i had it. i suppose i could use it on my boat if i needed to. lots of those old chevy engines around here in them.


Tom Greenleaf
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Jul 28, 2012, 7:59 AM

Post #19 of 25 (3246 views)
Re: running lean on GMC van 6.0 Sign In

Laugh - bet I have three kicking around and still needed. Can be used just to sense/test high voltage on a plug wire for those that still have them. Big buck S/O dial advance and would bet I can't replace the bulb in it now!

T



john M2
User

Aug 13, 2012, 11:14 AM

Post #20 of 25 (3188 views)
Re: running lean on GMC van 6.0 Sign In

the ending. i did not find anyone who had a pressure tester to borrow. i suspected the fuel pump and had the owner take the van where he wanted. it came to me dead and i got it drivable, but not perfect. he took it to the dealership in town. they diagnosed it as fuel pump and $1,200 to replace. he was able to get a pump at the parts store cheaper and faster, they even worked with him on the labor price so it was about $900 to do it. runs good now. thanks to everyone for all the help. it would have been a real bear putting that pump in here especially with the butler carpet cleaning unit installed in the van, makes getting to things a lot harder.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 13, 2012, 11:59 AM

Post #21 of 25 (3180 views)
Re: running lean on GMC van 6.0 Sign In

$900 in labor alone!!!!!!! You got to be kidding That's maybe $300 to $400 in labor.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



john M2
User

Aug 13, 2012, 12:16 PM

Post #22 of 25 (3174 views)
Re: running lean on GMC van 6.0 Sign In

the pump he said cost about $225 dollars from the auto parts store, and the rest in labor. i don`t remember the exact numbers but it seemed high to me.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 13, 2012, 12:20 PM

Post #23 of 25 (3171 views)
Re: running lean on GMC van 6.0 Sign In

There are a few different tank setups but the most expensive one is 2.7 hours which at $100 per hour would be $270 plus diagnostic fees.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



Tom Greenleaf
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Aug 13, 2012, 12:20 PM

Post #24 of 25 (3168 views)
Re: running lean on GMC van 6.0 Sign In

Appreciate the follow up on this and best hopes that it stays fixed now. Man I know the "aggregation" factor of a specialized vehicle. Oh gawd - who did they call (retired now) who would be the sucker to crawl under,over and who knows to get at what? The monsters needing fuel pumps of course had 7 zillion gallon tanks which were full of course. About now just a sign saying 'free gas' would solve it.

Sounds a bit pricey still but can't say what they might have gone thru. No matter as losing biz over it is no deal either,

T



john M2
User

Aug 13, 2012, 12:30 PM

Post #25 of 25 (3162 views)
Re: running lean on GMC van 6.0 Sign In

yeah i didn`t have time to do it here, no lift and outside in the florida summer time heat. not to mention it rains almost every afternoon. the tank didn`t seem very big, maybe only 30 gallons, or at least what i could see of it. just glad it`s fixed for him. now i have to fix a power steering leak and bad passenger front caliper on his other work van. it is always something.






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