My buddy just got a new DMAX LLY and was saying he went up to about 12,000 feet in Colorado and his truck wouldn't start. It finally did restart and has been OK since. I recently went up to the Sierra's and was at about 7,500 feet. I had statrted the truck after it had been sitting over night and after about 20 seconds it died. Would'nt restart. I bled the fuel system and it fired right up and no problems since. Talking with my friend it seems we both did a major elevation change in a short period of time. I am wondering what would cause this problem. Anyone else have this happen?


I was think it was a pressure difference in the fuel tank that caused n air bubble or something after the truck sat a while.

Same thing with me. Morning after the first overnight at 8,600 feet at Yosemite it momentarily fired, then stalled. I tried to bleed it but no air came out. Then it started after a few more cranks. Also the temperature was in the mid-30's the night before.


Afterwards no more problems at the same elevation/temps for the rest of the week. I've been to the same spot the year before without any problems.


This was the first/only time I've ever had a rough/slow start problem.

Come on Tech's or other knowledgable folk we need some answers!!!

Sorry, I am not a tech and cann't give you an answer, but I do use my truck at high altitude and have not had your problem.

My brother and I travel between Phoenix (at 1,100 ft) and the White Mtn. of Az (at 9,300 ft). I have a 2004.5 LLY and he has a 2003 LB7. We have never had starting problems, hot, cold, transition, overnight, etc. Also, I have never talked to anyone up there with a Durmax that had trouble starting the truck. I am thinking it is not a common problem.

Maybe some of the Colorado members have some ideas.

BigdaddyG & Mr X,


I had the same problem over a years period when the truck was new. I go camping a lot. While in the High Sierra's or Desert (in winter), anytime the night temps got below 30 deg F the truck would not start the next morning. Had to prime as described. A very repeatable sequence.


The first time I changed the OEM fuel filter, I noticed that it had been installed by the factory very loosely. I had all sorts of band style wrenches ready to go to take the filter off and it just spun off without any effort by hand. Installed the new filter per instructions and the NO START PROBLEM disappeared. The truck has been working fine now for 2 years. So in my situation, the no start was related to an air leak at the fuel filter. Cold temperatures opened the tolerance up enough to create an air leak.


Anyone experiencing this type of problem, first check to make sure the fuel filter is installed correctly. Even to the point of taking it off and putting new one on.





Hope this helps,


Alan

I think it may be a air leak... like a loose filter or bleeder screw.

i would guess a loose filter... i myself didn't have my CAT filter tight enough once.. not tight enough to run poorly at sea level, but enough to weep when i installed the lift pump. after that i started making them tighten and no leaks!

High altitude/low temp stresses on sealed systems cause makes sense. Stuff like gas cans and bottles sealed at sea level bulge at lower pressure of high altitude. I've heard of those insulated double pane gas filled windows manufactured at sea level failing when installed up in the mountains.


I had just changed out my CAT/Nictane and OEM only about 500 miles of sea level driving prior to the mountain trip. It only happened on one of nine mornings at high altitude/low temp but i'll still go out and give both filters a little torque down - makes sense.

I live @ 5900 feet, and went up to Steamboat Springs this weekend. I was in Summit County (9,900 feet) and it is about 6800 in Steamboat.


No problems. None. Zero, zilch, nada. Ran up on a fresh tankful of diesel and stanadyne. Averaged less than 650 on the EGT (post turbo) and used less than 1/2 tank on a 177 mile one way trip. All this in an '02 CCLB Dually LB7 totally empty except for the family (4 adults and luggage).


http://www.dieselplace.com/forum/smileys/HiHi.gifEdited by: Diesel Dually

My educated guess is the same as hoots. A small leak somewhere. Remember, the pump does not suck the fuel to the pump. The pump creates a negative pressure. Atmospheric pressure pushed the fuel to the pump. A very small leak due to altitude or extreme temp change would allow the fuel to partially run back down the line. A piece of dirt under one of the check valves in the primer pump would probably cause a no start also. Later! Frank

I'll double check the filters for tightness but they haven't been a problem before. Temerature wasn't a problem on this trip. It may have gotten into the low 50's or so.


OC_DMAX we only live a short distance apart. I'm in La HAbra. Edited by: BigdaddyG

This happened to me in late June on MT. Evans and at Echo Lake park. Twice it wouldn't start, and less than 5 pumps on the primer did the trick. I did check both my filters and the bleed screw, all tight. This only happened at elevation, never happened before, or since.

Ok guys, Just came back from vacation with the buddy mentioned above. Both trucks did it again!!!! Both trucks fuel filter(s) and bleed screws are tight. This happend after a very steep down grade and going from 11,000+ft to about 7,000 ft. parked in the campground unhooked my trailer and pulled the truck forward a few feet and it stalled. Wouldn't restart. Opened the bleeder screw and it sucked in a bunch of air!!!! I didn't notice this last time but it was plainly audible this time. Primed the truck, fired right up and has run fine since. Buddy had his do the same thing a few days earlier. Heck if I know what's causing this but it obviously is not an air leak in the system hence the vacum that had formed. Any more ideas out there!!!!

I live in Phoenix, and two weeks ago went up to near Flagstaff, (change from 108 degrees, 1100ft to 60 degrees, 7000 ft) . I had just installed a 45 gal Transferflow tank and CAT/ Nicktane filter. Tank was about 1/2 full. After unhooking our fifth wheel, truck died. Primed fuel filter about 5 times, it started, and died again after about 10 seconds. Primed again, and it started and ran. No problems since. I tightened both filters, and checked all lines, and have not had problem since.


Now, after reading of all your problems, I'm not sure if it was my installations, or altitude, or temps. Been starting just fine since back to PHX.

Ok guys, Just came back from vacation with the buddy mentioned above. Both trucks did it again!!!! Both trucks fuel filter(s) and bleed screws are tight. This happend after a very steep down grade and going from 11,000+ft to about 7,000 ft. parked in the campground unhooked my trailer and pulled the truck forward a few feet and it stalled. Wouldn't restart. Opened the bleeder screw and it sucked in a bunch of air!!!! I didn't notice this last time but it was plainly audible this time. Primed the truck, fired right up and has run fine since. Buddy had his do the same thing a few days earlier. Heck if I know what's causing this but it obviously is not an air leak in the system hence the vacum that had formed. Any more ideas out there!!!!


Something is not right with your system. Why would opening the bleeder screw let air be sucked in? Your gas cap is suppose to have a vent that allows air to be sucked in at that point, so that pressure is equalized.

If I am not mistaken everyone that has had this "not start at altitude" has a CAT filter (Nicktane). Last spring I had a problem with the CAT filter in my truck. Took a lot of checks and testing and suggestions but finally put an o-ring on my filter head threaded post to help seal off the suction side and no more start/die incidenats. Suggest an o-ring on the threaded post. Cheap and easy. Read this....


http://dieselplace.com/forum/forum_posts.asp?TID=9076&PN=6

I think Mitchagain has a point.


I have a Kennedy Megafilter installed post-OEM and since the weather turned hot I am experiencing stalls soon after start - mostly after the truck sits for a while. If the truck sits for a few hours, then it will stall upon starting. After I bleed the air out of the Megafilter the truck is good to go for a few days. This behavior is fairly predictable.... If I do not bleed the Megafilter after 1/3 to 1/2 tank of fuel, then it will stall due to air-in-filter problems.


When I first installed the Megafilter the weather was cooler and I had no stalling problems for several weeks. The weather turned hot (high 90's every day), and the air-in-filter problems show up.


My thoughts on what is happening are that hot fluids are less able to retain dissolved gasses (air). This air is coming out of solution and blocked by the filter media. During use, these gasses build up on the dirty side of the filter, and liquid fuel flows through the filter. When the truck is shut off and sits for a while, the air migrates through the filter media to the clean side. Once enough air has migrated to the clean side, the fuel system gets a big gulp of it upon startup, causing the stall.


Every time I've had a stall upon start-up, I have bled the filter and the engine then starts and runs well. Every time I've bled the filter, there has been a whole lot of air to bleed out - minimum 40 pumps, no more than 60 (yes, I've counted).


The altitude is roughly 1,000 feet here where I live, so no altitude issues here. However, vapor will expand when heated - just like it will expand at altitude. The vapor in the filter system may be cooking while sitting in the parking lot with the combined heat of the day and heat-soak from the engine. My current routine is to bleed the filter upon fill-up, and again before I go through 1/2 tank. Even so, I still do get caught by an occasional stall.


The last half of July I towed the travel trailer up to Minnesota & back, ~3,500 miles total. During this time I could go through 2-3 full tanks of fuel without bleeding the filter, and had no stalls unless the truck sat without running for at least a short time (like a stop for lunch). It's either a heat-soak issue or idle time for the air to pass the filter media, or a combination. Constantly running the vehicle somehow seems to keep the air on the upsream side of the filter.


I wish I could see what was happening... Are there clear fuel hoses available?


Edited by: HBruns

Mine never did this before. It only does it when I make a rapid altitude change. After repriming the truck I wont have any problems. It also does not do this every time. I made many altitude changes this trip crossing the Rockies and the San Juans. The change seems to need to be rapid followed by stopping the truck shortly thereafter. Wonder if it could somehow be the fuel cap not venting properly? Mine has done it once going up in altitude and once going down. My buddy had it happen both times after going up in altitude and he has a stock fuel system.

BigdaddyG, For a 2bit O-ring, its worth a try. I don't have a size, I grabbed several and measured against the bevel of threaded receiver on the filter for a fit. I am guessing its in the range of 3/4" to 7/8". Keep us posted.

Thanks Mitch, I was planning on trying it when I swap filters.

BigdaddyG, any update to your "no start" issue?


This past weekend Traveler11 came by the house and we installed a 7/8" o-ring on his Nicktane filter head. Surprisingly, when we removed the CAT filter the threaded nipple came out with the filter! We reinstalled the threaded nipple and snugged it down with a pair of channel-locks. We put the o-ring on the base of the treaded nipple and reinstalled the filter. Traveler11 is now motoring off into the sunset monitoring.


Maybe the loose nipple was allowing a little bit of air to slip past from the dirty side to the clean side, causing a loss of prime. Time will tell.

Thanks Mitch,


Never thought to check the nipple and I just changed filters a short time ago. Haven't been back up to alttitude since and everything is fine. Have to pick up a 7/8" O-ring too!

i doubt the nipple was loose until removed.. if you really torque the filter down (tighter than i tighten the nipple in the vise) then you can loosen the nipple when you remove it...


that being said, i don't see how the nipple being loose would cause a loss of prime unless something could escape from outside the filter's top seal... after all, the air would have to get in from the outside to cause any stalling...i myself have been guilty of not tightening the cat filter enough..

http://www.dieselplace.com/forum/smileys/smiley24.gifI'm wondering if a lift pump would solve all of these "no start" problems? That is if the needed "o" ring is installed at the secondary filter. I guess I really don't understand the logic of the factory not installing one in the first place. It's good enough; don't make it any better?

I got a cousin that works for CAT and he indicates that when they work on equipment in the field, mechanics install o-rings on the threaded nipples to keep issues from occurring from poor fitting threads on the filter to the threads on the nipples. Convinced me that the o-ring is a good idea. Its the only thing that could have been my problem when I replaced the filter last spring and suddenly had the "no start" issue. O-ring in place and no issues now.

Sounds like excessive vaporization in the lines. Heat and low pressure (vacuum) cause this. The vapor clooect and allows an air lock.





IMHO, the best solution is a lift pump. Still working on the controlcircuit, but pumps are ready. Keeping the fuel under pressure most of the time will prevent vaporization in my experience.





Sealing the nipple really does nothing more than prevent "channeling" of fuel or air through the threads. In fact, for those experiencing no starts with my Mega filter and NOT wanting to run a lift pump, we have a bleed orifice to enhance this and let the air pass rather than accumulate...Edited by: Kennedy