Crank but no start

[2001gmc36]

I have a 2001 gmc 6.6 duramax a few months ago when it would get below 50 degrees it would not go into gear when it had set over night , everything moved properly but it would not ingage. So I would put it into park and wait 10-15 minutes with it running put it in gear and it drove with no issues. I checked the transmission fluid and it was perfect. I read the nsbu's go bad and I bought one and it seemed to work but it still has problems every now and again but once it goes into gear it runs drives shiftes just fine and will not usually do it again unless it sits for a while or gets really cold. About a month later it was geting warmer and now it was getting harder to start but once it did start it ran good. So I bought a lift pump again that's what I kept reading about and that seemed to fix it for awhile but now Then i can take a 20 min drive shut it off And run into the store and came back and it will crank but wouldn't start so I opened the hood and checked if I had any leaks and everything looked fine. Waited probably 30-45 minutes and it started up no problem I thought it was a freak thing so I didn't think twice but now it is happening more often and the only trick I could do to fix it was hold the pedal to the floor and it would start and run and drive fine. So I started today and had to run errands and I never shut it off it ran great got on the highway great idled great then when I got back to the shop shut it off I tried to start it back and it would not start and hours later still will not start still cranks but won't start the primer pump is hard but there is no pressure on the fuel rail unless I turn the key on so the lift pump is on. The thing that really puzzles me about all of this is once it starts and goes into gear it runs and drives just fine no problems until I shut it off. The only codes I get are p0845,p0846,p0841,P1713 and the check engine light does not stay on long it will go off with out being cleared. I was told it might be my CPU has gone bad because I had a edge programmer on it. Does anyone have any ideas what might be going on. And I have already replaced the injectors and injection pump about 57,000 miles ago. Any ideas or help appreciated thank!

[DmaxMaverick]

Welcome aboard!

Is the Edge still installed? If so, remove it completely, and repeat. It is not an uncommon cause of similar issues.

Your failure to engage Drive is likely a separate issue. Torque converter drain-down would be about the most common cause. A shutdown and restart (once it warms a little) is usually a good remedy without tearing into the tranny. Colder temps and longer sits tend to worsen the occurrence.

[Kennedy]

On the crank no start issue it sounds like injectors are getting tired. 30-45 minutes later it has cooled.

[More Power]

Can you pump the fuel filter priming pump to remove air after the engine/truck has sat for a while (i.e. an hour - overnight)?

This will tell you whether air is able to enter the fuel supply. Jim

[2001gmc36]

I removed the edge afew days before it stoped running. I haven't been able to start it sence 05/22/19 and the priming pump is still as hard as a rock. But I do not have hardly any pressure at the fuel rail shraider valve unless I have my lift pump running.

[More Power]

I removed the edge afew days before it stoped running. I haven't been able to start it sence 05/22/19 and the priming pump is still as hard as a rock. But I do not have hardly any pressure at the fuel rail shraider valve unless I have my lift pump running.

There should be a slightly negative pressure (vacuum) at the Shrader valve with the engine idling - assuming no lift pump.

The following link will provide information for what are normal pressures/vacuum at the Shrader. https://www.thedieselpage.com/reviews/jkfuelpressure.htm

Jim

[bmoeller]

When I removed my edge (weird problems) I had to reseat some of the pins in the connectors. Apparently they can back out enough to cause your type of problem.

[Kennedy]

I hate to recommend an ether start, but sometimes that is what it takes. Very sparingly give it a little sniff while someone cranks it and see if it goes. If it goes we are back to injectors...

[More Power]

Or, have a tech with a Tech II look at injection system values (rail pressures, etc) while cranking. Maybe give the connectors another look to verify no more pins are pushed... Jim

[Kennedy]

It's just like the old 6.5 DB2 4911 pump. Hot no start. Let it cool and do nothing more and it starts. This progresses to a complete no start with the Dmax and in this case it is ball seat erosion from 2003 era second iteration injectors. A little sniff bumps the engine cranking speed up enough to move enough volume to get the pressure required to start.

To the best of my recollection the scan data will not show valid during cranking. Either way this is a textbook example of a condition I've seen many times before but not in recent years because most of those old injector bodies are long gone thankfully.

[DmaxMaverick]

.....Either way this is a textbook example of a condition I've seen many times before but not in recent years because most of those old injector bodies are long gone thankfully.

About what year should they have been purged from inventory?

[Kennedy]

About what year should they have been purged from inventory?

Over a decade ago with anything legit Bosch. The private shops who knows? I'm sure many keep recycling the same junk.

The story reads like Goldilocks and the 3 bears. Too hard, too soft, just right

2001-2002 production models had a tendency to crack and fill the crankcase

2003-2004 production models had a tendency to ball seat erode and give no start

Somewhere shortly after they were revised again. Most legit Bosch factory remans had new bodies already over a decade ago. Then the VCO nozzles started crapping out with the blue smoke drips.