Who is the 6.2 diesel expert around here?

[diesel4me]

Yes, and half throttle above 32 degrees. I have found best results by flooring it during every cold start, regardless of ambient temperature. Extra fuel isn't going to hurt anything, and seems to help.

My pickup almost acts like it is flooded when it finally starts,belches a cloud of white smoke at first for about 20 seconds,then you can see oil smoke while your letting it warm up at fast idle..but maybe that is "normal" for a 6.2..

My Burb tends to start better if I slowly depress the accelerator while cranking,it seems to have a sweet spot about 1/4 to 1/2 way down,where it starts firing and wants to fire up,if you go past that point or floor it,it seems to snuff out and it'll just crank till you kill the batteries..
I have no clue if anyone "turned up" the IP or messed with the timing,both trucks engines IP has the timing marks lined up..

Sometimes I wonder if the cold start advance actually works on my pickup,the fast idle solenoid does kick the idle speed up,but I don't know if it actually advances the IP timing as its supposed to..
I have it wired to a dash switch on both trucks..

 

[thatK30guy]

The smoking at the initial start up on mine is white and then turns blue-ish once it's idling on it's own. Then when it's warmed up it mellows down to a little bit of smoke. Same color, too.

 

[diesel4me]

Mine sounds like a few cylinders are loaded up with fuel and not firing when (if!) it first starts cold,kind of like a gas engine when it gets flooded,and it takes some time for the cylinders to expel the excess fuel and start firing normally..

I know this sounds like some glow plugs aren't working,but testing them with a test light shows they are at least conducting electricity--how hot they get ,I have no clue,I could take each one out and hook them to a battery with jumper cables,but that is something I don't feel like doing till spring..may as well just buy 8 new AC 60G's and install them,then keep any good ones for spares..but $90 for 8 glow plugs isn't something I can afford every winter--rather buy new batteries first..

While cranking it on a first cold start,the starter is spinning fast enough so the bendix drive starts letting the over-running clutch to slip just as the engine starts firing,you are probably familiar with the way it'll go "thump--thump--thump" when a cylinder starts to fire,then you'll hear the starter drive start to kick out and slip--if I could get like 25 more rpms I bet it would fire right up,but that is usually when the batteries start wearing down, and then your boned..

I suppose low compression is a possibility,I do not have a compression tester for a diesel,only gas engines..but judging how well it runs after its warmed up,and the small amount of oil it uses,(leaks more than burns any-) I do not think the engine is tired..

 

[campfire]

Mine sounds like a few cylinders are loaded up with fuel and not firing when (if!) it first starts cold,kind of like a gas engine when it gets flooded,and it takes some time for the cylinders to expel the excess fuel and start firing normally..

That is almost what's happening. Except, unlike a spark-ignition engine, a diesel is still able to ignite regardless of how rich the "mixture" is (and I use that term loosely). It's primarily a matter of heat, which explains how a few cylinders can start before the rest are uniformly warmed up. Then the others fire when they get hot enough. That's also why the smoke changes as the engine warms up.


Grid heaters try to solve this problem by heating all the incoming air, but there will still be variations in cylinder temperature.

 

[thatK30guy]

New issue update:

Last night (12/5/19) I fired up the truck to get the fluids moving and batteries charged up in 50 degree temps. After the third heating of the GP's the truck fired up but while I held the pedal down slightly to rev a little higher.
I sat in the truck holding the pedal down for about 5 minutes and wanted to move it backwards about 20 feet to make room in front of the shop. It idled roughly in reverse until I stopped and then put it in forward gear to straighten it out. It died. I turned the key and it fired right up but died right away. Did that about 5 more times and then gave up. Figured the truck is dead now and won't hold an idle.

What's up with that?

 

[campfire]

New issue update:

Last night (12/5/19) I fired up the truck to get the fluids moving and batteries charged up in 50 degree temps. After the third heating of the GP's the truck fired up but while I held the pedal down slightly to rev a little higher.
I sat in the truck holding the pedal down for about 5 minutes and wanted to move it backwards about 20 feet to make room in front of the shop. It idled roughly in reverse until I stopped and then put it in forward gear to straighten it out. It died. I turned the key and it fired right up but died right away. Did that about 5 more times and then gave up. Figured the truck is dead now and won't hold an idle.

What's up with that?

If it gets better when you hold the pedal down, it may just be air leaking into the fuel lines. If it does not get better, and you have good fuel flow to the IP, it sounds like IP issues.

Do you have a fuel pressure gauge rigged up yet? Do you see air bubbles in the return line?

 

[thatK30guy]

If it gets better when you hold the pedal down, it may just be air leaking into the fuel lines. If it does not get better, and you have good fuel flow to the IP, it sounds like IP issues.

Do you have a fuel pressure gauge rigged up yet? Do you see air bubbles in the return line?

It won't rev up at all. Tried to press the go-pedal down to get it to run but mash the pedal it just won't do anything now but die after turning the key.

 

[campfire]

It won't rev up at all. Tried to press the go-pedal down to get it to run but mash the pedal it just won't do anything now but die after turning the key.

But it starts readily? Definitely sounds like a fuel delivery problem. You just need to figure out whether fuel isn't getting to the IP, or whether the IP is failing to dispense it.

 

[KirsL]

It's definitely starving for fuel. It's running on what's in the filter and the lines. I had a similar issue with mine, there was no noticeable leak. It ended up being the short soft fuel lines right at the sending unit. The lines were older and they had swelled up. They were open just enough for the electric fuel pump to eventually fill the fiter, but not keep the engine fed.

 

[diesel4me]

If the cold start advance switch and fast idle solenoid isn't working it may want to stall at idle too,until it warms up..
I let my truck run at fast idle,holding the pedal down a bit for at least a minute or so (longer if its really frigid),before I try putting it in gear or applying a load..even with the cold start advance and fast idle solenoid working it sometimes doesn't want to run at idle smoothly for at least a minute or so..

I had an issue with the pink wire that gives 12V to the fuel shutoff solenoid on the IP when I first got the truck too,it was a loose fit on the terminal and it shook off twice going over rough roads and it stalled,refused to start again--and would make it stumble at times,probably when the engine moved on its mounts just enough to pull it off or make & break contact..
I cut the original terminal off and crimped a new one on,had to cut the wire back about 1" because it was gangrene with corrosion..

The fuel shut off solenoid sits in a "bowl" inside the IP and it isn't unheard of to have one start working intermittently or die ..
Don't ask me how an electrical solenoid can sit in diesel fuel all its life and not start a fire when it decides to short out..

 

[imiceman44]

If the cold start advance switch and fast idle solenoid isn't working it may want to stall at idle too,until it warms up..
I let my truck run at fast idle,holding the pedal down a bit for at least a minute or so (longer if its really frigid),before I try putting it in gear or applying a load..even with the cold start advance and fast idle solenoid working it sometimes doesn't want to run at idle smoothly for at least a minute or so..

I had an issue with the pink wire that gives 12V to the fuel shutoff solenoid on the IP when I first got the truck too,it was a loose fit on the terminal and it shook off twice going over rough roads and it stalled,refused to start again--and would make it stumble at times,probably when the engine moved on its mounts just enough to pull it off or make & break contact..
I cut the original terminal off and crimped a new one on,had to cut the wire back about 1" because it was gangrene with corrosion..

The fuel shut off solenoid sits in a "bowl" inside the IP and it isn't unheard of to have one start working intermittently or die ..
Don't ask me how an electrical solenoid can sit in diesel fuel all its life and not start a fire when it decides to short out..

You can not start a fire in a pool of diesel, not even with a flame, let alone a spark.

 

[diesel4me]

Yeah,a co-worker at the junkyard liked to scare people by tossing a lit cigarette in a 5 gallon bucket full of old diesel fuel we drained from the loader,in the winter it would never ignite,it would just go "pssst" and go right out..even in summer,it was unlikely for that to ignite the diesel..

One day I argued with him,that it "might" possibly ignite on a warm enough day,he said "No way--not diesel fuel----I would bet even GAS wont light off with just a cigarette..

So yup,just to prove his point,he had to get a pail of stale gas from one of the junk cars we'd just got in and had drained,and he flicked his cigarette into the bucket...and it took a few seconds,but it suddenly went "WHOOOF" and he almost got his beard singed off!...it was about 40 degrees out,and we had a tough time extinguishing the fire,the bucket melted after a few seconds and we had a small river of flaming gasoline heading towards the office!..good thing there was still some snow on the ground!..

I should have taken that bet!...he insisted it was a "fluke" and that the gas probably had some dry-gas or other additive in it.