6.2 Diesel starting abnormalitiy

[Dabba]

So, I recently got the truck back from the shop. I had them do the glow plugs since they were shot, and I didnt want to take the risk, also it was freezing out.

Anyway. At temps of about 10-40F the truck starts right up, but sputters out within a few seconds. Usually i start with the pedal halfway or all the way to the floor. When she starts I get a lot of that blueish smoke and the smell of diesel. She sputters out when I back off the pedal to lower the rpms.

When I go to start the second time, it usually takes about 10-15 seconds of cranking where she sounds like she's just about to start with me pumping the pedal. She starts and I keep the RPMs high for about 5 seconds before letting off the pedal slow and then she just idles as normal.

This is only cold starts. After shes warmed up, even if the plugs need to cycle a little shes fine. I dont know if it makes any difference but I put some antigelling stuff in the tank.

 

[tRustyK5]

Double check the rubber fuel lines and any hose clamps. Sounds like you're getting a bit of air, and a fuel drainback issue. My pick-up does the same, yet if I park it so the nose of the truck is even slightly downhill the problem is much reduced.

 

[diesel4me]

Rene is right,any air getting in the lines can cause this...even with air tight lines I think its just the nature of a cold 6.2 to not want to idle "instantly"...perhaps your cold advance or the fast idle solenoid isn't working too?..


My pickup's 6.2 wants the pedal fully floored cranking during a cold start,when its below 30 degrees out,otherwise it wont fire up and stay running,it'll idle a few seconds,you can hear one cylinder not firing consistently, and it'll stall out...it will fire right up again OK though,and once I get it to fire up & run I let it rev up to about 2500 rpms and hold it there for about 20 seconds,by then its running smoothly,the misfiring is gone, and you can let it idle without stalling..guys I know who drive big rigs tell me "never let a cold diesel idle right away"...they claim it can glaze the bores up bad with soot and cause big troubles..
I like to let it run at fast idle a good minute or two,longer if its frigid out ,before driving away ..once its warmed up,it'll start without touching the gas pedal and idle fine..


Pumping the pedal doesn't really help,since its fuel injection and your not pumping fuel in like a carb's accelerator pump--but I've noticed on my other trucks 6.2 it is quite sensitive to the amount of throttle you give it,like it has a "sweet spot" in the injector pump where it'll fire more consistently and start easier--my Suburban seems to fire up cold at 1/4 throttle the best,if I give it more or less than that it seems to not want to fire up,you can crank it till the batteries wear down,almost like it floods out. I found by moving the gas pedal slowly from idle to floored while cranking there was a spot at 1/4 throttle where it started firing and wanting to start the most--holding it there usually gets it to start much faster...

I can tell you this--if you dont have two good fully charged batteries,the glow plugs all working (or in my pickup's case,7 out of 8!) and a starter that whips it over full tilt,your chances of getting a 6.2 started below 15 degrees above isn't too great,at least in my experience..especially if it has a lot of miles on it..

 

[Dabba]

I'll do my best to check the lines, though i've never done that before so I'm not too sure how. Snow is coming tomorrow so if it's anything extensive ill have to wait. It's always the same starting it, not better or worse so who knows, and I can definitely understand that "sweet spot" She seems to start the second time around when I hover around it.

Plugs are good, batteries are good, high idle is good, but I have another question for you guys.

When she first starts in cold weather like now, I put my foot to the floor and as I said, she starts right up, but I just cant see having a cold diesel with RPMs that high as being anything good for it, at least just upon startup. So i try to ease off the pedal and thats when she sputters out. I take it I'm correct in you don't want diesel sitting in a high RPM range when it's just been started?

 

[tRustyK5]

Try for 1000-1500 as long as you see good oil pressure. I wouldn't go much more than that willingly. As for checking the lines and clamps...screwdriver is all that's needed. A lot of guys will double clamp all rubber fuel line clamps. A leak that will cause problems could be minor enough not to have fuel leak out at all...but will cause a bit of drainback and an air void after sitting overnight.

 

[blazinzuk]

I concur, you have an air leak somewhere. My 6.2 will start below zero when all is well without being plugged in. Yah it chugs for several seconds but no biggie

 

[black dawg]

what year truck? Do you know what brand glow plugs were put in it?

Depending on the glow plugs, they might not be getting hot enough, and can act just how you describe.

 

[diesel4me]

I've been revving mine up to 2000-2500 after it first starts in the cold ,and so far it hasn't blown a rod or spun a bearing,though it sounds like it might--after 10 years though,I would think if it didn't like being revved that much it would have...the fast idle on my pickups 6.2 might not work,it doesn't seem to have fast idle,though you can feel the gas pedal move when you turn the key on...

If I dont floor my pickup when its cold it wont want to stay running or start as quickly,and if I dont keep it at a fast idle several seconds it will sometimes snuff out...

I have 60G AC glow plugs with a manual button,and I leave them on for at least 10 seconds (I use my seat belt buzzer as a timing guide!)...I also leave them on while cranking it over too,and if its really cold,I'll even leave them on 5 more seconds after it starts up,you can hear the difference if you dont...

The fast idle in the Suburban's 6.2 works,it might even be a bit "too" high in my opinion,but the fan probably makes it sound faster than its really running..the engine in that truck doesn't sound as "loose" as my pickup,that might be due to the injector timing,I haven't looked to see if it might be advanced on the pickups 6.2,it sounds more "diesel rattly" than the Burb does...the Burb has about 155K on it,supposedly the pickups engine had only 80K ,it was a salvage yard replacement--how true that is I cant say...truck shows less than 38K on the oddometer,I think it lunched its original engine at low mileage and it sat a long time in someone's garage before I bought it!..

 

[Massboy]

I did the resistor mod on my glow plug module and put in 8 new Kennedy Diesel quick heats. I depress my fuel pedal completely then turn on my ignition fully. I let my fuel pedal come back and then, when the glow light goes out, I start the truck. I do not need to add any gas or anything else and it runs damn near perfect with just a little rumble here or there but the glow controller comes on and off a few times which helps it even out. Even though it is in my garage there is no heat unless I'm working in it and the garage is concrete block making it a very cold building. I have a couple buckets of water that have been frozen most of the winter in my garage.
Your fast idle solenoid is adjustable for idle speed and most of them let go or people don't set them proper before trying to start the engine. The solenoid should give it enough fuel for it to stay running without additional pedal.

 

[AR_K5]

Do you have a water seperator on your truck to remove water from the fuel?
How long has it been since you changed your fuel filter?
Are you letting the glow plugs warm up before you crank the starter?

You should not have to pump a diesel.

I know you said you put anti gell in it but never said what kind.
Take it from a career truck driver, Howes is the only brand worth using (my opinion). It's very good stuff. And works wonders on cold starts.

If that doesn't work then have your injectors bled.

 

[Dabba]

Ill have to go over the lines when it's a little warmer. And next time im messing around in the garage ill check to see which anti gel i used.

I dont know what plugs they used. And yeah, when she first starts she's at much higher RPMs than the high idle so naturally i want to let off the gas right away, but then she stalls. I'd rather have to restart than risk damage.

Next time I start im going to try to cycle the plugs a few times first.

Stupid question but. how would I find out if Im getting air in the lines at a certain area without seeing fuel leaking or cracks in the line?

 

[Fred_M1010]

When I go to start the second time, it usually takes about 10-15 seconds of cranking where she sounds like she's just about to start with me pumping the pedal. She starts and I keep the RPMs high for about 5 seconds before letting off the pedal slow and then she just idles as normal.

Do you mean that if you failed at the first attempt, it will crank longer before it starts the next time?

If so, it depends on the glow plug module.
GM have a really stupid way to determine temperature for glowing...
It measures the resistance of the glow plugs to determine how cold it is.
The glow plugs gets a higher resistance the hotter they are.
So if you have just tried starting and failed, the glow plugs are warm and tricks the controller into thinking that the engine is hot,
so it glows for a much shorter duration of time.
So wait a minute or two, before trying again, if it doesn't start on the first attempt.

But it does sound like you have some other problem as well...

 

[MrSchaeferPants]

Stupid question but. how would I find out if Im getting air in the lines at a certain area without seeing fuel leaking or cracks in the line?

Remove the fuel return hose coming off the IP, that leads to the "T" hard line. Replace with a clear fuel rated hose. I got a foot or so clear hose that's meant for small engines at the parts store. You'll see bubbles in the line. This will only show that you have air in the system, it will not tell you where air is entering from.

The other method is to disconnect your fuel line, and run compressed air backwards towards the tank (5psi or so), and you could spot a leak that way, or hear it.

Here's a good general read on the subject: How to remove air from the fuel system and/or find an air/fuel leak on a 6.2L

 

[diesel4me]

I've used several different brands of diesel fuel treatment like Power Service,Siloo,STP and the Howes Lubricator,and I noticed they all seemed to help my pickup start better in the cold,the Howes more so than the others--I liked the Siloo stuff too,but they went under I think...haven't seen any for sale around here in years...

I bought 4 cans of Siloo from a guy at a flea market last year,thats the only place I might find any now..
Howes was selling for 10.99 at the only place here selling it I used to work at,its probably a lot more now,not having bought any in a year or more..

I started my Suburban's 6.2 up yesterday,with only ONE fully charged battery I took out of the Caravan !..surprised me,its usually a bear to get fired up,it was maybe 30 degrees out,it did take a lot of cranking before it finally roared to life though..the fuel in it is 4 years old and is probably a mix of diesel,kerosene,and possibly some bio-diesel or other "abnormal" stuff,the former owner ran it on anything that burned--I added some fuel treatment to it last fall...
Its only been started a few times in the past year too..might have water in with it by now too I suppose..after running it a few minutes it sounds good still though..I bet half the glow plugs are not working on it too,I only replaced a few on the drivers side and made sure those all worked--passenger side may have a few dead ones still..

 

[AR_K5]

Seriously, (I may have missed it) when did you last change the fuel filters?
That's the first thing you should do. If they have water in them they can plug up in cold weather. Also something else nobody seems to think of is a block heater, does it have one? If so are you using it? If both are "no", get one. Air in the lines is unlikely (imo) unless you have ran it out of fuel.

*Don't forget to fill the fuel filter before you install.*

 

[diesel4me]

Yeah,putting one on empty is a bad idea!...friend replaced one once without knowing about "bleeding" a diesel's fuel system ,and ended up frying the starter,before he got the truck to run again...

I hear some guys suggest filling a new filter with diesel fuel treatment or ATF and it'll supposedly clean the injectors,but I always feared it might run away or do something bad running on 100% cleaner?...and ATF might have friction stuff in it,so I'd be leery of using that too...I read about some stuff Standyne sells for just that purpose...

I rarely use my block heater because its a tank style one that goes in a heater hose,and only about 500 watts,it dont seem to heat it up much unless I leave it on all night,and it jacks my electric bill up a lot...

One thing I dont understand--what happens when you drive somewhere you cant "plug in",and it sits outside for several hours in sub zero weather?...what good is the block heater then?...thats why I like my diesels to start without having to use one...or starting fluid either--seems once they get "addicted" to ether,they refuse to start without it at any temparature!....
--are we supposed to walk, or buy a gas powered vehicle to drive in the winter?....the way this winter has been,I'm reluctant to go anywhere in my truck for fear I wont be able to start it if I leave it parked all day..(if I had new batteries it probably wouldn't strand me though!)..

 

[AR_K5]

The block heater is simply to keep it above freezing, not warm. If you are going to be in exteme cold make sure filters are new, keep some Howes in the fuel. If no plug in for block heater leave it idling (f its not going be all day)if its going to leave you stranded.

Yes, ether (starting fluid) is like crack to a diesel engine, they get hooked, and it will burn out your glow plugs.

ATF was recommended for keeping injectors clean "back in the day" before there were so many additives in it. Today there is debate over ash from the burnt additives possibly causing problems. So I tend to avoid advising one way or the other on that. I know folks who add a quart to every tank, it's something for you to research and decide on.

Hard starts in cold weather are just part of owning a diesel powered vehichle.
You have to stay on top of the batteries and the fuel, or they simply won't start.

 

[diesel4me]

True enough,with a diesel,there is no getting by with marginal batteries or a few dead glow plugs when its really frigid--or untreated fuel..here it usually does not go much below 20 above often,or for long...till THIS winter!.....

I usually had no problem getting my truck started once it had been fired up in the morning,even if it sat 8 hours at work in 20 degree weather,it was only if it sat overnight (and especially outside) it might not fire up if its block heater wasnt plugged in or the batteries on a trickle charger..

I guess owning gas powered vehicles spoiled me,I liked being able to just hop in and GO,without having to unplug,worry about whether it'll spin over fast and long enough to start if its really cold out,etc...

I have seen propane powered block heaters for big rigs,that would be an option if you live in arctic conditions ,but to me its just another thing to buy you'd not use often enough to justify having,plus having to keep propane canisters on hand for it....(can you picture yourself at work waiting an hour for enough heat to build up so it'll start,so you can go home?..dont sound like fun to me!)..

Now with diesel fuel being much more than gas costs,I'm finding owning a diesel isn't always such a good idea for a person like me who isn't driving it far daily,short trips and lots of cold start cycles wear one out faster and kills the batteries and glow plugs and decreases fuel mileage..whatever you "save" ends up being eaten up by the cost of parts when they fail...

For me I'd be better off with a old school straight six in many ways,but I'm unlikely to find one around here thats any good now,or be up to a swap if I did ,the truck isn't really worth that much effort any more either...anyone else but me would have probably scrapped it a long time ago..if I do end up lifting the 6.2 up to replace its rotted oil pan and exhaust manifolds and I did happen to stumble across a straight six or a small block,I'd be very tempted to go back to gasoline though..