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rtphillips370
07-07-2011, 08:05
Ive combed through the forums here for a few hours and haven't been able to find a solid answer per sey for my problem.

Truck: 1999 C3500 6.5TD w/Kennedy Intercooler, U.S. Diesel parts aftermarket ECM and matching mechanical turbocharger modification to increase boost, U.S. Diesel Parts aftermarket high performance injectors, and the heartland 4" performance exhaust system. This spring, I had a new IP installed, and a new PMD was installed last summer, mounted externally over the left wheel well near the master cylinder. Truck has 174500 miles total, with less than 1500 miles on the IP and 2500 miles on the PMD (I dont drive this truck in the winter).

Problem: When hot, after a modest drive of 10 miles or so with the a/c on, park it and come back in fifteen min or so, it will not start, takes extremely long protracted crank cycle(s) to start.

Observations: On initial key turn to power the pre-start sequence, the WAIT TO START light does not come on for the usual 10-20 sec period of time, rather it blinks on once then off, no usual pump sound under my seat (soft humming sound during the 10-20 second WTS light is on).

When it does start, it cough a huge amount of black smoke and then runs as if nothing is wrong.

Ive searched through here on the hard start probems, and most appear to point to a old IP or PMD both of mine are effectually new. Looked up the lift pump issues and I dont see the problems most of those point out, anyone out there give me a clue or hook me up with a good link to a thread that is the most pertinent to this? it is quite baffling and very frustrating after all of the money I have sunk into this truck. My initial guess is either a lift pump going out or maybe a glow controller? but again after reading through a large number of threads, I am more confused than when I began, any help in pointing me in the right direction will be greatly appreciated!

joed
07-07-2011, 11:58
Couple thoughts...

Any codes?

It almost sounds like you are loosing power to the PCM - I have experienced the short 'flash' of the WTS light after disconnecting the batteries.

When it does this, have you tried shutting the key off, waiting 15-20 sec, then turning it to run again? If you then get a normal glow cycle and it starts well, power supply seems to be an issue.

Could also be the aftermarket PCM - have you tried the stock one? If it starts okay stock, the aftermarket PCM probably needs to be reflashed.

Issues with the glow controller should set a related code.

Hope that helps.

Joe.

rtphillips370
07-07-2011, 13:01
Yep I have tried the turn off wait and then try again, sometimes it works sometimes it does not. yesterday, when during one of its extended cranking fits, it finally went "click" and not crank. I cleaned the battery terminals and it cranked and eventually started.

This morning, I did go through all of the battery terminal cables and made sure they are clean and covered in electrolitic grease. I dont have the original PCM as I had to return it for the core charge, I'll have to double check for codes but it hasn't lit up the light sdvising of any pending codes yet.

rtphillips370
07-07-2011, 15:20
Adding to the mystery, went to the store this afternoon, after coming out, the WTS light went through its normal pace, heard the lift pump run etc and still hard to start, took nearly 15-20 sec worth of cranking to light up.

HH
07-08-2011, 05:36
If not PMD, could be IP head. Does it start fine when cold? or after cooling off? Did the IP rebuilder test test the pump? What about filters, last change?

rtphillips370
07-08-2011, 06:44
The pump was purchased direct from the GM parts division, I got a new pump not a rebult one. I changed the fuel filter on 6-30-11 before my road trip with it up north.

joed
07-08-2011, 07:09
I would check for codes - not all codes will turn the SES light on, but will be stored in history.

If it's doing it that often, a code should be stored.

If not, could be the FSD/PMD. Bad FSD won't always set a code. Have you tried hooking up to the one still on the pump (if it's still there)?

Joe.

JohnC
07-08-2011, 10:21
Make sure the lift pump is working correctly and the fuel is not leaking back into the tank from the engine compartment. Sounds like you're loosing the prime on the pump.

If it doesn't start, cycle the key off an back on to get the pump to run again. Do that a couple of times and see if it fires better after.

rtphillips370
07-08-2011, 12:46
The above-described lack of a pump sound is intermintent with the problem however, regardless if the pump is working as usual or not coming on, it still giving the starting problem, I have also tried the key / pump trick you describe and no changes in starting issue.

JohnC
07-08-2011, 14:17
First you must confirm the pump works. Just because it makes noise (sometimes) doesn't mean it's pumping fuel (sometimes...)

rtphillips370
07-09-2011, 08:15
First you must confirm the pump works. Just because it makes noise (sometimes) doesn't mean it's pumping fuel (sometimes...)

What would be a good way to confirm it? would opening the valve on top of the fuel filter be enough or would I have to crack a fuel line or some other process?

JohnC
07-09-2011, 10:42
If you have a fuel pressure gauge (also commonly known as a vacuum gauge) you can connect it to the water drain hose and open the water drain valve. You should have pressure , or at least not a vacuum, whenever the engine is running and for that 10 second or so interval after you switch the key on. I think it should also run when the starter is cranking.

You can test the "running" part by opening the fuel filter bleeder while it is running. If fuel squirts out, you're good. If not, and it stalls, then you're not good. Ditto opening the bleeder while it is in the 10 second prime phase.

handcannon
07-09-2011, 20:21
While you're doing all this pressure testing, replace the IP fuel return hose with a clear line so you can moniter for air in the return fuel. A piece of quarter inch clear plastic line about six to eight inches long is all that's needed. Watch for any bubbles in there. You may end up with one tiny bubble that stays in the very top curve of the line. I wouldn't worry about that. Be looking for a continuous stream of tiny bubbles flowing through.

Some of your hard start (long cranking time?) description sounds almost like air in fuel problems. Air in fuel will act almost like a gasser motor with a flooded carb. Crank and crank, finally spit and sputter, die, crank some more, spit and sputter and run a bit longer, maybe die again, crank and finally stay running, but will be rough for a bit and then slowly smooth out. If it tends to be like this after a warm start then I'd definately be looking for air in the return fuel line.

I deal with air in fuel problems on an old 83 6.2 pickup that I just run occasionally on the place here. I have modified the fuel system to make it easy for me to bleed out the air to reduce starter cranking time.

Just be careful not to crank too much without giving the starter time to cool off. These starters are not cheap and will burn out when overheated.

Don