Long cranking times before combustion

[VRidgley]

As a long-time observer of hearing diesel engines start, I know that they usually fire up immediately on cranking. My unit, a first purchase of a 2 week-old 2006 Ram 2500 with less than 500 miles, is exhibiting inconsistent cranking behavior. In most cases of warm starts, the engine fires within 1 second of cranking. However, in most cases of cold starts (engine temp cold or less than 100, air temp around 50-60), the cranking is taking 4-5 seconds. (I've been timing it and keeping a log of the starting conditions. ) Does this sound familiar to anybody, or have an explanation?

 

[jeff1lisa]

I have a 2005 Ram 3500 with 37,000 miles and it is taking forever to fire as well. . Had it at the dealer once and the checked all kinds of fuel pressures and different things and couldn't find anything wrong... And of course it doesn't do it ALL the time... Any one else having this problem??

 

[starkmr]

Yep, do a search here and you will find it. I asked the same question myself a couple of months ago. It is the nature of the 3rd generation CTD and is not a problem (well, until you have to replace a worn out starter anyway).

 

[Troll]

I thought it was just my imagination, I had an 03 and it fired right up, and since I picked up my 06 about 2 weeks ago I keep thinking that I might have a problem because it seems to crank longer than my 03. I wonder why it takes so much longer?

 

[Hoefler]

Have to build pressure in the common rail.

 

[HNelson]

I don't it's a 3rd gen thing... it's an 06 thing. My 06 does it every once in a while, doesn't matter whether it's hot or cold. My 05 always fired right up. There's a TSB out for it, but the people that've had it done say there's no difference.

 

[mberry]

Hoefler and HNelson,



With all respect, I would have to disagree with you both. First, mine is intermittent also and I think it has everything to do with the lift pump taking a little longer in certain conditions to build pressure to the CP3, not the CP3 having to build pressure.



Obviously it is not an '06 thing only. I will admit that it is more pronounced on the '06's for sure.

 

[Regcabguy]

Fords

I think a 3rd gen on its worst day is light years faster than a current Ford. We drive Hinos at work with direct injection that start like my '99. A coworker gets back in his Ford and has to readjust to the multi-second start.

 

[BTighe]

im sure i read in a past TDR issue that it was due to the DM flywheel. my dealer told me that the tsb was a reflash and it isnt worth the time it takes. said they would let me know when they have something thatll fix it. not that it bothers me.

 

[schlack]

I have the same problem on my 06' and I was told its only on the manual trans. I took it to the dealership and they flashed it which fixed it for about a week. I find that if you crank for more than two seconds turn the key back then crank it and it will fire right up.

 

[JTH]

I Had The Same Problem With My '06, Very Long Cranking Times. I Took It To The Dealer And They Reflashed The Computer Because There Was Actually A Technical Service Bulletin From Chrysler.

 

[TowPro]

I Had The Same Problem With My '06, Very Long Cranking Times. I Took It To The Dealer And They Reflashed The Computer Because There Was Actually A Technical Service Bulletin From Chrysler.

so did I, And I still have the problem, only not as often. Maybe its not as often since its warmer out now (summer). Until someone comes up with a real fix, I will have to live with it.

 

[DieselFiend]

my buddy had an 05 that had a long crank issue. Didn't matter whether it was warm or cold out. It drove him nuts. He started arbitration because they couldn't fix it then wound up trading it in on a Nissan. Mine always fires right up though.

 

[05mxdiesel]

I have the same issue here and there as well. It is definatly way better than my old 95 psd that took 9-10 seconds of cranking and then another 4-5 just to get oil pressure.

 

[DMork]

I have an 06 2500 Mega Cab and upon stopping at a fuel station on the way home with the truck, I could not believe that I had a 12 sec crank to start. Again with it cold, it started in about 2 secs. There is something wrong, but I am not on board with just turning the programmers loose with a new flash of the day. Been there, done that. I will wait till I hear of a solid fix. Also really frustrated with the Overdrive ratio in the 6 spd transmission. Seems rediculous to run 1900 RPM at 60 MPH. With the performance characteristics of the truck, I wouild have liked to seen about 1700 to 1750 at 60 MPH. Any economical ideas???



________________________________________________

2006 2500 4x4 Mega Cab SLT 6 SPD Atlantic Blue

 

[betterthanstock]

This spring I have replaced my lift pump (was still running ok) with another Cummins approved (10 psi) lift pump (I made a little adapter kit, PM me if interested). It runs smoother with this than with the stock filter-mounted pump.

Anyway, I can just barely hear this pump when turning on the key, and I have noticed that usually it runs for about 3-4 seconds, but sometimes it does not run at all. Every time it refuses to run, it starts right away. I have come to the conclusion that the ECM knows if you have fuel pressure, which is hard to believe, given that the rail sensor has a +- 500 psi precision.

My theory is that fuel drains from the rail thru the lift pump (which has a check valve) and thru the injectors, either into the engine (not so good) or into the fuel tank via return line.

When more fuel drains out than usual, let's say something is not perfectly closed, it takes longer to bleed the air out of the lines, and it takes a couple of seconds longer to start.



The solution is to always wait until the lift pump stops, which is about 3-4 seconds, before cranking. You will also hear the injectors clicking, as they are bleeding air bubbles back into the fuel tank. Then it should start in 2-4 turns of the starter.

If you wait too long after the lift pump has stopped, fuel will leak out again, because the injectors are still bleeding the fuel lines back to the fuel tank. Maybe this is what they are reflashing to correct.



When you change fuel filters, bump the starter, which lets the lift pump run for 30 seconds or so, then crank it.

Sometimes, when the engine is hot, there may be other causes, such as battery sensors not matching the inlet air temperature, which confuses the ECM for a couple of seconds, or you could even have vapor lock, like a gasser, if the engine is real hot, like DMork may have had. (or there may be something else wrong with his truck)

 

[hotram03]

I have a nephew with an 05 and my brother with his new 06 and both have this problem. I think its because the ECM checks in on all sensors as it cranks, and I think the cam and the crankshaft sensor are not synced up, and it takes alittle longer to get them in sync to allow fuel for the fire, just a thought.....

 

[JMergl]

I agree, 6th gear just doesn't seem to do it. It is rediculous to be at 22 for 65.



06 3500

 

[AMink]

I'm glad I'm not the only one who noticed this. My 97 pops right over, one or two spins of the starter and we're off. My 06 definately takes longer. It's not terribly long, but noticeable. I do let the pump run til it stops before trying to start the truck. There have been a few times when I let the key go before it fires, just cause I'm used to how quick the old truck fires up.

 

[wcjp]

The reflash helped my 06' somewhat. Occasional long crank persists. My liftpump will run for sometime when turning the key without starting the truck.