6.5 Hard cold start
 

1993 K3500 6.5 TD is a having a very hard cold start. It usually takes about 1-2 min of cranking. So far I have New injectors(standyne), new AC delco 60g glowplugs, new lift pump, new fuel filter, new CDR valve, and a new air filter. Truck has 162K miles. The main problem is that the truck will start very hard after sitting for 2+ hours and after it does fire it runs very rough and blows alot of white smoke for about 1 min, after that the truck doesn't skip a beat and runs perfectly. The truck has always kinda started hard but one morning it got a lot worse. The decline was not gradual.
Here are all of my tests and observations-
-It always starts perfectly when hot. I know common DB2 failing symptoms are hard hot starts.
-I have tested power at all of the glows and they are all working. I get about 5-10 sec. of glow in 60 deg F temp.
-While cranking my tach will read anywhere from 1000 to 3000 rpm and sometimes will not read at all, however once the truck starts running the tach seems to work normally.
-There is a problem with the starter where it will crank over slowly for about 10 seconds and then speed up to normal speed, this just started recently and I assume its because I am an idiot and was cranking to long. Does this sound like a dying starter? FYI it was still starting hard before the starter started acting up.
-Truck passes the lift pump test, I don't have a pressure gauge but I can definitely feel pressure at water drain T valve with engine running.
-I also have a dead OPS sensor, I get 12v at the pump but the pump won't run through the OPS circuit. I think I read something about how the contacts inside the OPS are to small and can still pass volts to the lift pump but there will be to much resistance for the lift pump to run. Either way I have it Jumped and its running. Also I know that driving it with a non working lift pump is bad for the injection pump, I have driven it that way for about 500 miles and who knows how long it was driven that way by the previous owner. It started hard when I first bought it (5-10 seconds of cranking) and lots of white smoke. I figured it just needed new glowplugs. So anyway could I have caused damage to IP and is there a way to test/check? I only recently stopped driving it when the hard starting got suddenly worse.
-I have checked the HPCA solenoid on the injection pump and when I apply 12v to it I can hear it click. If I engage and disengage it while the engine is running the engine idle will change So its at least doing something.
-I have a clear fuel return line on the top of the IP and I usually have no bubbles or 1 very small one after letting it sit overnight.
-CTS sensor is open while hot and closed while cold, tested good.
-Lift pump makes more of a clack clack clack noise rather then a normal fuel pump wirrr. Is this normal? FYI it passes the lift pump test.

I have run out of ideas and I don't want to replace the IP unless that is for sure the problem. What do you guys think?

I'm having the exact same issue with my 97 and I can't figure it out either

Slow cranking along with a worn IP might be you whole problem?

What you perceive as normal cranking speed might just not be enough?

Replace the starter with a 28-MT gear reduction starter with the proper nose support bracket and be sure that the battery cables are clean and secure with no corrosion under the insulation.

2 700 CCA minimum batteries for turning these over as well.

When were injectors last replaced? Fuel could be leaking into cylinders which would cause hard start after sitting? there any injector knocking/pinging noises?

All above could be causing this or combination of symptoms. Whats the condition of the battery cables. The oem cables on these rigs are barely adequate new let alone the corrosion from years of age. Ever since I upgraded cablesBattery and glow harness my truck cranks much faster and starts the second I hit the key with no smoke.

My injectors, lift pump, return lines etc etc was all replaced less than 2 weeks ago

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Ill definately check into that, that makes sense because when cranking my batteries seem weak to me but it only happens after it sits for more than a couple hours

1 thing I wonder about is if this is a seasonal problem?
Depending on the climate you live in,winter fuel might compound the problem of slow cranking and a worn IP in warm weather due to it's thinner viscosity.

Are you still running old fuel or have you tried starting with summer fuel yet?

I fuel my truck every time it needs it, idk the difference this my first diesel, I know I sound stupid but I'm being honest, all I know is when the truck is warm it starts first crank no smoke after it sits a couple hours it cranks and cranks and cranks and has A LOT of white smoke

Ok back to slow cranking speed and/or low compression.

I've had the compression tested its getting good compression