Still haven't had a chance to pull plugs to check on it yet - but hoping to get a chance this week when I can run the truck then let it sit for 12-15hrs or so...but will also do the throttle body clean trick again as well and report back and start going from there. - Does anyone know what pressure it should likely hold in the system after sitting for a period of time?
I did gamble Riverbanks on an aftermarket - but had quite a number of high reviews with satisfied owners - but it could definitely be a possibility that it’s got its own faults built right in from new. But because it’s literally the identical pressure observations, stumble, etc. (and it does run at 61 psi not 55 as previously posted, my mistake) I’m still leaning toward something else playing a factor. But I’ll have to keep plugging at it. - speaking of does anyone think plugs would play a factor? In my own experiences on other machines/engines...... it seems like they cause more notable issues or stumble/hesitation when warm, or at low idle, or under a load.....and I’ve got none of that. Just the start up stumble.
I'll do that! And yeah - I had wet in my head but your right that a plug that's darker or is notably different from the typical lighter brown/etc. would indicate that it's not firing up to speed at first due to excess fuel.
That'll definitely help Jg - The wet plug thing could work...but unless that particular cylinder happened to be at TDC it probably wouldn't have leaked enough fuel into the cylinder to get the plug wet unless I try and start it for that 1-2 seconds and immediately shut it off to start checking plugs for a damp one....but that could work. Plugs could likely use a change anyways TBH. I did head gaskets and they of course looked fine so I cheaped out and left them which was a lazy approach. But even finding out which bank could be a good start or at least eliminate some testing time to isolate that side vs doing them all. I'm going to cheat a little bit with a little injector cleaner or MMO in the next couple tanks (not really expecting much though) of fuel, but not expecting much. Then it'll be over to a buddy that's got the proper equipment to watch for a rich condition.
Hey guys - I've searched it a few times here and other places on the web with mixed suggestions or solutions, but I've developed a situation where my '06 2500 6.0L has a rough start/stumble for about 1-3 seconds once it has sat over a period of about 8hrs or more. It certainly seemed like a fuel issue, so after some testing I was getting over 60 on my initial key turn - then erratic spikes and drops for a quick couple seconds on first start up/roll over while it stumbled and then level at around 55 psi or so and ran flawless/purred like a kitten after that. When shut off it would bleed down to 50 after about 5 minutes, 48 after 20 minutes, 35 after about 45 minutes and so forth until a few hours it would be dead 0 psi. I've read (or assumed) that the system (unless there is a leak) should maintain some pressure regardless of being sitting for hours. Knowing that a lot of these quirky issues are caused by failures in the pump I went ahead and changed it out and it since it had 270K on it anyway. The results were - - - very similar. If I come out to test the truck after sitting an extended period I have 0 psi and not even a little squirt of fuel when I go to install my gauge on the schrader valve which right off the bat leads me to believe I've got bleed down somewhere. When I turn the key and can hear the pump clearly turn on, pressure up to 61 or so...then drop to 55 after it quits that first 1-3 second cycle period....try to roll over and get a stumble/erratic fuel pressure till it fired and levels off flat at 55psi and purrs after that initial couple seconds. Steady after that/no hesitation/etc. - So does my next suspect sound like a sticky injector that's allowing fuel to bleed off and possibly get a little bit of air or hesitation in fueling initially creating the stumble or is there somewhere else I should be looking first?? I don't think it is an air or intake gasket leak since they've been changed and the fact that it only lasts a few seconds even when dead cold. I've cleaned the throttle body/MAF previously (within the last 3-4000km) but could try that again however I don't think that's my issue here. If it is a suspect injector - is there any way to test for the one(s) that may be causing the problem specifically by getting someone with a more detailed scanner tool?
Had the same exact issues on an ‘07 3500....I could clean the sensor and any rust/etc.off the sensor and mounting surface...and it would be good for a short period but return. However I read someone else’s issue and how it was actually also a wheel bearing jusssst starting to go out. I didn’t have any real audible hum or usual sounds though. I suspected it was the driver’s side as that sensor had appeared to have more build up/rust staining and sure enough - I changed it out with a rather inexpensive aftermarket wheel bearing and sensor assembly from Amazon (one with decent reviews) and voila!! Problem has been solved for the last couple months.
I hear you Markmx6 - I know that's the right answer for sure. The joy's of owning an older truck of course, but this way I don't feel so bad when a bang a few trees of her in the bush vs. brand new paint!
Thanks Asilver - I’m 99% that changing the pump will be the solution. I’m now just wondering how much of a gamble it is to continue on doing a double key flip first thing in the morning for a little while. I’ve read that guys have had similar issues for years before there is any real pump failure. But that typically if these types of issues start showing up the pump itself could just take a crap at any time too based on its age.
Hey fellas - think I know my answer but figured it wouldn’t hurt for a second opinion...but recently my ‘06 3500 6.0 sat for a couple days and when I went to start it, burped and didn’t fire. Second key turn it started, stumbled for a couple seconds, then it was fine. The next morning it fired on the first roll but did have the stumble for a second or two - - - so I started thinking fuel pump. However throughout the day it fires up just fine, even after sitting from morning till lunch, etc. So I bought a pressure gauge and got to testing... I’ve got 55psi with key on, not running. Steady 60 psi at idle running. - key off it drops back but holds 55 - after 10-15 mins drops to under 50-48 - hour to two hours drops to 30 - by morning dead 0 I would think it should hold SOME pressure even overnight, so thinking bad check valve or pressure regulator - both of which are in the pump on an ‘06. Maybe draining off enough pressure/fuel overnight that even though it bumps to 55 right off the bat, there could be air or space still in the system at the injectors which is why the initial burp/stumble since it doesn’t last very long at all. - so I’m assuming I’m likely looking at a new pump assembly since with 265km on the clock, even fixing something minor (valve/regulator) would be a bandaid. BUT.... should I also be worried this pump is giving me the telltale “wink” that it could crap out any day/time or could I possibly run it for while doing the double key cycle truck in the morning since that seems to help. Just spent a bunch of $$$$ moving so if this is the only issue I have to deal with for a bit till I can change it out that’s fine, but if the pump is saying “change me now!” So be it I guess. Thanks guys!!
Thanks a lot fellas… I figured it was just since I haven’t been driving it for a while and now I’m only noticing it since my Ford work truck does not do the same type of fluctuation/variation from idle to higher RPM. So it stood out. I also did head gaskets so have been really paying close attention to everything more since
Hey guys - I'm just wondering how high is too high on a GM 6.0 for engine oil pressure. I had the truck down and out for a little while so I wasn't driving it regularly until recently - but I just don't seem to recall the oil pressure fluctuating quite as much as it does now in the past. And maybe it's just because I've been driving it more and watching it a little more closely??? However, I'm typically I'm seeing around 280 KPA at a cold idle/start-up (~ 40 psi) which at a warm idle is down to about 210 KPA (~30psi). At highway speeds warm I'm anywhere from 2200-2800 RPM I can see towards 400-410 KPA (~ 58-60 psi). I've not seen it go above that though. Seem normal or is something seeming a little odd??
Thanks for the reply Davestar - I'll go back and chat more with the tech about what you mentioned above and see what they say or what they can do as well. I may be misinterpreting what he was meaning, since he said he was quite familiar with the issue and given that I haven't been driving it for an extended period with this happening, having clean fluid, and little to no debris on the magnet - he said that it was likely that changing the converter out would be a fair solution. No guarantee......which is still the kicker of course.
Well - the verdict is in. After trying to replace the TCC Solenoid in my transmission to try and solve an Overdrive slippage/non-lock up issue with no change, I had the transmission tech guys come along for a drive with their Tech Scanner...and he's 99.9% that the OD clutch plates have simply run their course. Everything he could view was signalling that the right messages/proper pressure/etc. are being sent and that the transmission is trying everything it can to lock up the converter in OD - but not happening. He also said that it's typically what he's seen and that they may not show any symptoms or slowly have this happen...they just eventually fail which is why it's not locking up on the highway and throwing codes (P0894). SO - - - I'd love to hear a few opinions on whether or not to replace just the converter (approx. $1-1,200 with labor), or if I should replace the whole transmission as I can get a rebuilt with warranty ($23-2,500 with labor) since all the other tranny components also have 270,000km of wear and tear. It seems that the converter is typically what fails as it is continually slipping and locking/etc., and there was nearly nothing for debris in the pan or on the magnet and the fluid looked like new so aside from this slippage issue occurring, before that the tranny worked perfectly. It has not been driven long since this started to happen. Saving over $1000 would be really great right now - but having to turn around and spend the $2500 again within a year because of some other failure is not. So just wondering if guys have done just the converter with good/fair results with the 4L80e or if they've had the rest of the tranny grenade within 20,000km afterward???
Well - the verdict is in. I had the transmission tech guys come along for a drive with their Tech Scanner...and he's 99.9% that the OD clutch plates have simply run their course. Everything he could view was signalling that the right messages are being sent and that the transmission is trying everything it can to lock up the converter in OD - but not happening. He also said that it's typically what he's seen and that they may not show any symptoms or slowly have this happen...they just eventually fail. SO - - - I'd love to hear a few opinions on whether or not to replace just the converter (approx. $1-1,200 with labor), or if I should replace the whole transmission as I can get a rebuilt with warranty ($23-2,500 with labor) since all the other tranny components also have 270,000km of wear and tear. It seems that the converter is typically what fails as it is continually slipping and locking/etc., and there was nearly nothing for debris in the pan or on the magnet and the fluid looked like new so aside from this slippage issue occurring, before that the tranny worked perfectly. Saving over $1000 would be really great right now - but having to turn around and spend the $2500 again within a year because of some other failure is not. So just wondering if guys have done just the converter with good/fair results with the 4L80e or if they've had the rest of the tranny grenade within 20,000km afterward???
Thx Bruce...I’ll see if my Trans guy in town has a Tech 2 or similar scanner that’s more capable....... as for temps, I’ve not yet seen anything above 140. And I’m watching it like a hawk (weekend truck - not primary) to make sure it doesn’t go anywhere near past 200
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