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GearHungry
@qwest.net

GearHungry

Anon

[Help] 99 GMC yukon Sputters and dies

So I Have a 99 GMC yukon SLE. It's been on and off sputtering and dying, but will run perfect for months on end until it just collapses randomly. I've changed the full pump twice, in-line fuel filter, entire exhaust piping with cats(it needed to be done bad), and I've run all the fuel delivery system tests. I will constantly have fuel pressure up to the engine within optimal range even when it sputters and dies. It doesn't seem to throw any codes when it dies however so that's a hassle. I've tried driving the absolute piss out of it to just through even 1 code but nothing. It used to throw engine missfire in cylinder 4, but I did a full tune up with spark plugs, distributor, rotor, and leads; it hasn't thrown that code since. The only thing i've noticed, is that I can drive drive drive everywhere, full Horsepower, gas mileage is great, then it fluctuates RPM between 500 and 2000, jerks my car back and forth, then dies (happens alot when i try to put throttle into a hill (even a small hill)). But the things idles just fine all the time (except for after a sputtering incident). I can keep the car from dying by only staying within 1-1.5 thousand rpm as of recent (wasn't able to do that 2months ago). I feel like it's injectors, ECM, or ground issue. What ya'll think? ( I also forgot to mention it pulled one code a week ago, then went away, for crankshaft data intermittent, but i was a hill and was sputtering. )

MooJohn
join:2005-12-18
Milledgeville, GA

MooJohn

Member

If the ECU doesn't see a signal from the crank sensor it won't spark and/or run the fuel pump. This is generic for all vehicles but I'm assuming it applies to yours too. My last GM truck had the TBI 350

Looks like the crankshaft sensor might be the primary culprit as mentioned here:
»www.tahoeforum.com/showt ··· ?t=13105

mattmag

join:2000-04-09
NW Illinois

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I would start by looking at the crank position sensor as well. Make sure the connections are clean and tight, and no damage to the harness. You won't be able to test it without a lab scope really, so if everything else looks OK I would replace it. I hate throwing parts at cars without diagnostics, but the CPS is a bit beyond the ability of a DIY guy for proper diagnosis.

Xstar_Lumini
join:2008-12-14
CANADA

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I had exactly this problem with a Chevy Venture minivan 1998. My mechanic found out that the problem was that a wire harness was on top of another one at the back of the engine and one of them had made the other harness bald from the friction from rubbing each other. He just wrapped both of the harnesses with electrical tape and the problem was fixed.

I had a similar problem months later again and he checked the harness, it was still intact, so WTH? It turned out to be an air sensor that regulates flow for the fuel or something like that.

Anonymous_
Anonymous
Premium Member
join:2004-06-21
127.0.0.1

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said by GearHungry :

So I Have a 99 GMC yukon SLE. It's been on and off sputtering and dying, but will run perfect for months on end until it just collapses randomly. I've changed the full pump twice, in-line fuel filter, entire exhaust piping with cats(it needed to be done bad), and I've run all the fuel delivery system tests. I will constantly have fuel pressure up to the engine within optimal range even when it sputters and dies. It doesn't seem to throw any codes when it dies however so that's a hassle. I've tried driving the absolute piss out of it to just through even 1 code but nothing. It used to throw engine missfire in cylinder 4, but I did a full tune up with spark plugs, distributor, rotor, and leads; it hasn't thrown that code since. The only thing i've noticed, is that I can drive drive drive everywhere, full Horsepower, gas mileage is great, then it fluctuates RPM between 500 and 2000, jerks my car back and forth, then dies (happens alot when i try to put throttle into a hill (even a small hill)). But the things idles just fine all the time (except for after a sputtering incident). I can keep the car from dying by only staying within 1-1.5 thousand rpm as of recent (wasn't able to do that 2months ago). I feel like it's injectors, ECM, or ground issue. What ya'll think? ( I also forgot to mention it pulled one code a week ago, then went away, for crankshaft data intermittent, but i was a hill and was sputtering. )

fuel regulator...

GearHungry
@qwest.net

GearHungry

Anon

(thanks for the help by the way): UPDATE: so I replaced the sensor, checked the gap between the sensor and crank and it was fairly close. Ran no problem, even at high RPM, and with aaggressive driving. Did this for around 10 minutes no sputter. let the car sit for 10mintues idling normally. Then on my drive home I sputtered until I died. (also learned that all this had killed my batteries voltage storage [oh the fun]) Got a jump and drove back to the shop, I drove extremely rough to get a code; finally got something. Firstly I heard a weird almost whistling noise, like a fan first kicking on till it reaches its highest point, or maybe a vacum line? I'm not sure, but it was loud (regulator vacum line?) then random missfire commenced for the entire drive back, knocking, shuddering, all the same signs of bad fuel pump, but getting optimal fuel pressure the entire time. I'm at my wits end guys. please help me!!!

mattmag

join:2000-04-09
NW Illinois

mattmag



Take it to the shop of your choice or recommended by a friend. Some things just can't be fixed over the Internet.

Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium Member
join:2001-04-19
1970 442 W30

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said by GearHungry :

Then on my drive home I sputtered until I died. (also learned that all this had killed my batteries voltage storage [oh the fun]) Got a jump and drove back to the shop,

A car will sputter when there is less than 12 volts in the battery (the fuel pump, ECM and injectors stop working as the voltage goes lower) . Are you sure your alternator is not bad?

scanner
@optonline.net

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In addition to everything else, seeing the live data while you are having the issue can help a TON. Everything now would be a guess, however while you are having the issue if you can see what the truck is seeing you might find the problem very fast (or not at all) but something as random as this is hard to track down with out the right tools (it would turn into a throw parts at it job).
Keefer21
join:2012-07-06
Hilton, NY

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Sounds to me like a you need a new spider/ CPI unit. The fuel injection on the 4.3, 5.7 & 7.4's 96-2000 (dont quote me exactly on those years) Used CPI unit which resembles a spider. pressure regulator, injectors are all one unit. the actual injectors used poppet valves which get crudded up and get stuck shut or open etc, also being in the upper manifold the tremendous heat deteriorates everything & the lines to the injectors get brittle and leak too as well as the diaphragm in the regulator, its all one unit.

you have some tell tale signs. Ive had to replace the CPI first on my 94 s10 blazer, then my 98 suburban & recently on my 99 Tahoe. great strong engines but the CPI seems to be biggest high mileage issue i have ever had with those engines.

The new CPI units are new & improved with different injector heads & better plastics. the 94 blazer i mentioned had the CPI replaced at 190,XXX.. was still purring like a kitten at 475,XXX until a drunk rear ended me & put the old dinosaur out of commission. so needless to say the you'll get a lot of life out of the new CPI

Hows the exhaust? notice a ton of soot? smell like raw petrol coming out of the tail pipe?.. all bad CPI symptoms.

Good luck!