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1993 k1500 6.2/4l60e, 136k miles.


Can a bad IP cause hard cold starting, weird black smoke problems, and hair loss in the owner from stress?

My truck has issues cold starting. It will fire right up at 15 degrees, even if it's sat for a month. Colder than that, I'd have to plug it in. Once I hit ~-10F or so, I'm forced to use a kerosene torpedo heater. Even if I leave it plugged in all night, it's a guaranteed no-start. Block heater is new 1kw unit that I replaced this summer.

Had a few super tiny bubbles in the fuel. Fixed the leaks, and the problem remains.

When it's being a hard starter, when it finally starts I get a big cloud of black smoke for a few seconds. Also when I'm pulling hills or merging on the highway I can't tune the ugly black haze out. It started last fall. I replaced injectors shortly after because it was time, but the smoke remains. It's enough to leave a haze behind me when pulling moderate hills and slowly turns my rear alloy rims black.

During my fiddling with the starting issue, I found that my IP won't adjust past the line. It'll advance almost a quarter inch, but it stops completely and won't go past it in the retarding direction. Makes me wonder if something is buggered up internally or the timing chain is off by a tooth, if that is even possible. It seems like setting the lines to even has helped starting somewhat, and it needs heat for less time to go. I've owned the truck for 48k miles.

My compression is a bit low on this motor. It had a rough life as a milsurp. Hot compression is all in the low 300s, 320+/- 15psi. Gauge is very cheap, so I don't put too much faith in the numbers. I may have it verified on one cylinder by a shop or someone willing to lend me a better gauge.

Basically I'm trying to figure out this issue, because if it persists the truck can't serve as a daily anymore. I'm in Fairbanks AK, so winter is half of my year.

Glow plugs are new, and work well. GP controller is newer, the last one went out 2 years ago and I didn't want to do a push-button because hey, the old one lasted 25 years. Starter works well and spins fast. I've tried jumping it to get some more cranking speed when it's cold, and it's no help. EGR has been disabled. All of the common black smoke culprits (air cleaner, filter, etc) have been checked multiple times.

I may put a push button in just to see if a few extra seconds of glow changes my life for starting. But even if I get the starting ironed out, I really need to fix the black smoke. It's embarrassing and not too neighborly in a place that gets temperature inversions and air quality alerts in the winter.

The engine runs smoothly and has good power. It has a slight vibration at high r's, but that was there before the issues.

I'm just throwing out everything I can think of, because I'm out of ideas. Can an IP cause black smoke on acceleration/starting and hard starting? What's up with the IP advancing but not retarding? I feel like timing chain slop would allow extra movement in both directions. Will I be throwing money down a hole putting an IP on an engine with these compression numbers (assuming my crappy gauge is accurate)?

When it's not frigid, my exhaust on startup is completely normal. No white smoke to indicate low compression, so the lower numbers surprised me when I tested it last week.

Cheers and thank you for any ideas.
 

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One of the most common issues and hardest to find/fix is air in fuel issues. Everything from the tank to the IP must be rock solid and air free.
Incorrect timing issues will cause hard starts, black smoke
Low Compression is not a good thing to have. Anything in the low 300's is considered a tired motor
Dirty air and fuel filters will cause issues
Manual fuel pump or electronic lift pumps can cause issues
Fuel Gelling can create issues in colder climates.
Adding a Manual Glow plug overide will give you more glow time and help with cold starts in those colder climates
 
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Discussion Starter #3
One of the most common issues and hardest to find/fix is air in fuel issues. Everything from the tank to the IP must be rock solid and air free.
Incorrect timing issues will cause hard starts, black smoke
Low Compression is not a good thing to have. Anything in the low 300's is considered a tired motor
Dirty air and fuel filters will cause issues
Manual fuel pump or electronic lift pumps can cause issues
Fuel Gelling can create issues in colder climates.
Adding a Manual Glow plug overide will give you more glow time and help with cold starts in those colder climates
I appreciate the ideas. I've gone through the obvious and basic steps.

Air has been eliminated. Timing is suspect. Filters are all changed 2x/year which is overzealous but it's an old tank and I live on a dirt road, so it's cheap insurance. Truck idles fine with bleed valve wide open indicating adequate lift pump pressure. Gelling is not an issue here, they switch over to winter fuel well in advance and it pours fine at -60. I need to confirm those compression numbers especially since it runs so well once it's going.

Any input on the weird timing line phenomenon would be appreciated. I think my order of operations is to confirm the compression with a better gauge (preferably one that costs more than 45 bucks). If the smoke problems can't be resolved I'll hunt for a replacement motor for the summer and sell it off as a woodgetter/summer truck if I can't find one.
 

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I appreciate the ideas. I've gone through the obvious and basic steps.

Air has been eliminated. Timing is suspect. Filters are all changed 2x/year which is overzealous but it's an old tank and I live on a dirt road, so it's cheap insurance. Truck idles fine with bleed valve wide open indicating adequate lift pump pressure. Gelling is not an issue here, they switch over to winter fuel well in advance and it pours fine at -60. I need to confirm those compression numbers especially since it runs so well once it's going.

Any input on the weird timing line phenomenon would be appreciated. I think my order of operations is to confirm the compression with a better gauge (preferably one that costs more than 45 bucks). If the smoke problems can't be resolved I'll hunt for a replacement motor for the summer and sell it off as a woodgetter/summer truck if I can't find one.
Timing Chain slop will be a factor. If you think the chain has some slop I would Inspect it
I would verify TDCO.
If you use a timing light: Timing with a timing light
Info from the 6.2L FAQ page regarding timing : timing advancement
 

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1993 k1500 6.2/4l60e, 136k miles.


Can a bad IP cause hard cold starting, weird black smoke problems, and hair loss in the owner from stress?

My truck has issues cold starting. It will fire right up at 15 degrees, even if it's sat for a month. Colder than that, I'd have to plug it in. Once I hit ~-10F or so, I'm forced to use a kerosene torpedo heater. Even if I leave it plugged in all night, it's a guaranteed no-start. Block heater is new 1kw unit that I replaced this summer.

Had a few super tiny bubbles in the fuel. Fixed the leaks, and the problem remains.

When it's being a hard starter, when it finally starts I get a big cloud of black smoke for a few seconds. Also when I'm pulling hills or merging on the highway I can't tune the ugly black haze out. It started last fall. I replaced injectors shortly after because it was time, but the smoke remains. It's enough to leave a haze behind me when pulling moderate hills and slowly turns my rear alloy rims black.

During my fiddling with the starting issue, I found that my IP won't adjust past the line. It'll advance almost a quarter inch, but it stops completely and won't go past it in the retarding direction. Makes me wonder if something is buggered up internally or the timing chain is off by a tooth, if that is even possible. It seems like setting the lines to even has helped starting somewhat, and it needs heat for less time to go. I've owned the truck for 48k miles.

My compression is a bit low on this motor. It had a rough life as a milsurp. Hot compression is all in the low 300s, 320+/- 15psi. Gauge is very cheap, so I don't put too much faith in the numbers. I may have it verified on one cylinder by a shop or someone willing to lend me a better gauge.

Basically I'm trying to figure out this issue, because if it persists the truck can't serve as a daily anymore. I'm in Fairbanks AK, so winter is half of my year.

Glow plugs are new, and work well. GP controller is newer, the last one went out 2 years ago and I didn't want to do a push-button because hey, the old one lasted 25 years. Starter works well and spins fast. I've tried jumping it to get some more cranking speed when it's cold, and it's no help. EGR has been disabled. All of the common black smoke culprits (air cleaner, filter, etc) have been checked multiple times.

I may put a push button in just to see if a few extra seconds of glow changes my life for starting. But even if I get the starting ironed out, I really need to fix the black smoke. It's embarrassing and not too neighborly in a place that gets temperature inversions and air quality alerts in the winter.

The engine runs smoothly and has good power. It has a slight vibration at high r's, but that was there before the issues.

I'm just throwing out everything I can think of, because I'm out of ideas. Can an IP cause black smoke on acceleration/starting and hard starting? What's up with the IP advancing but not retarding? I feel like timing chain slop would allow extra movement in both directions. Will I be throwing money down a hole putting an IP on an engine with these compression numbers (assuming my crappy gauge is accurate)?

When it's not frigid, my exhaust on startup is completely normal. No white smoke to indicate low compression, so the lower numbers surprised me when I tested it last week.

Cheers and thank you for any ideas.
"hard cold starting, weird black smoke problems"

Engine Timing. Most common. to the Left (Towards Passenger side) is Advancing, To the Right (Drivers side) is Retarding. Its shouldn't be more than 4 Degree's. TMK.
 

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There is a lever on the passenger side of the injection pump. With the engine idling, use a screw driver to fully depress the lever, the engine should stumble. If the engine doesn't stumble, the advance piston in the injection pump could be worn. Does your cold advance solenoid work? It advances timing when engine is cold via the lever. Typically black smoke is from retarded timing, move injection pump towards drivers side to advance. When advancing timing, diesel rattle will increase, when you retard it rattle will quiet down. Try advancing 1/16 of an inch or slightly more. Check fuel heater in filter housing to see if it is working, super cold fuel is harder to ignite. Usually diesels will have more of a grey smoke at idle when very cold out, it is mostly caused from unburnt fuel and usually goes away once some heat is built up in the engine. Test your engine when plugged in by feeling with your hand to see if the block heater is actually working, engine should feel warm. Cords go bad on block heaters all the time.
 
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What glow plugs did you use? If you use the wrong plugs with the controller they wont heat up properly and cause hard starting. I believe you need 9g's to work properly. Also have you checked each is actually getting 12v when glow plugs are energized?
 

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Discussion Starter #8
I can't recall which plugs I ordered, but I think they were from diesel RX. All getting 12v, all get red hot in a few seconds at 20 degrees. I tested each one before snow flew. This morning after sitting for 13 hours at 0 degrees it fired like a champ. So the timing tinkering has made progress. I think I have a gremlin, and am starting to doubt those compression numbers after this morning's start. Plus, though I have some blowby, it's pretty wispy and unimpressive, so I'm trying to find someone with a snap-on diesel gauge.

Anyone with input as to why my pump won't retard past the timing lines aligning? I don't feel like that's normal. I could be completely wrong, as my timing experience has been "sounds right, starts well, tiny puff of blackish smoke when you romp it which instantly dissipates".

Full disclosure, I now see that I have completely misunderstood the procedure for testing timing by engine stumble D. Camilleri. I've always known that lever as the light load advance (?) and when a military diesel mechanic described it to me 5-6 years ago when I got my first 6.2 he said to bump the idle advance, which I interpreted as the high-idle pin. In my brain, depressing the high-idle pin would advance the timing a hair, as there was no engine load. I'll go grab the dunce cap.

I think we could all stand to revisit some "common sense solutions" we came up with in our early 20's.

Thank you for the ideas folks!
 

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Tiny puff of black is totally normal for these when you floor it. That doesn't phase me at all. Only thing I can think of is either a little more playing with the timing or you could have the tiniest of air leaks making it hard to start right off the bat. As for the rotation of the IP, I have had to wedge stuff in to get it to move before when all the lines are hooked up. Dont want to do too much of this because you're effectively bending the lines a little to move the IP.
 
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