Fuel filter assembly and limp mode

[KompressorMan]

My 01 has for the past 6 months or so intermittantly set off the limp mode when pulling a heavy load (10-16 thousand pounds) I took it to the dealer and he couldn't find the cause the first time, but now I took it back again and he say's the whole filter, housing and all needs to be replaced. I haven't been on the site in a while and a search didn't reveal much, but is this something that has been going on with these trucks? How can the housing fail? BTW, they quoted about 6-7 hundred for the part. Dang???

[DieselMonk]

if your truck goes in limp mode, there should be a code stored in the enginge computer. What was it? Did you try a new fuel filter first? I would guess that your rail pressure went low... anyhow, find out if you don't know what the code was. Also check the Fuel Pressure Regulator.

[BowTieDmax]

My 01 did this a while back and it was the fuel filter. We had about a 9,000 enclosed trailer and we were heading to Alabama from nothern Ohio. Well after are first fuel stop we got back on the highway and was on the throttle to get up to speed and all of a sudden we just lost half are power. It would only rev about 2,000rpm. Well we maintaned about 45mph untill we got to the next exit and we checked things out and there was nothing we could see. So I thought maybe it was my chip going bad so I took it out. Well I started the truck and held the throttle to the floor and it went right to 3200rpm so we took off again. Well long story short, anytime we came to a grade and you tried to maintaine speed, it would do it again but if you pulled over and shut it down for a couple of minutes you were fine. So after about 30 times we were there. It was night time with no were to buy a filter, and we had to be there in the morning. So we had to keep going. I learned to keep a spare filter in the truck after that. The fuel was from flying J and when I removed the filter it was full of larger size rust and crap. I would quess that by shutting the truck of the dirt would "fall away" for awhile.
I know this isnt the "real , default to 3rd gear limp mode" but not sure if this is simular to what you are seeing. My filter was about 3 weeks old at the time.

[Kennedy]

Did they confirm DTC P0093? I'd suggest you spend your money where it will do some good. Add lift supply and possibly filtration. I seriously doubt that the factory filter head is bad.

I've also seen plenty of cases of the "phantom limp mode" with 2001 trucks. We switch them to 2002 programming with my KD Custom tuning and the problem goes away.


http://www.kennedydiesel.com/images/pumpfilter_dmax.gif

[Kennedy]

My 01 did this a while back and it was the fuel filter. We had about a 9,000 enclosed trailer and we were heading to Alabama from nothern Ohio. Well after are first fuel stop we got back on the highway and was on the throttle to get up to speed and all of a sudden we just lost half are power. It would only rev about 2,000rpm. Well we maintaned about 45mph untill we got to the next exit and we checked things out and there was nothing we could see. So I thought maybe it was my chip going bad so I took it out. Well I started the truck and held the throttle to the floor and it went right to 3200rpm so we took off again. Well long story short, anytime we came to a grade and you tried to maintaine speed, it would do it again but if you pulled over and shut it down for a couple of minutes you were fine. So after about 30 times we were there. It was night time with no were to buy a filter, and we had to be there in the morning. So we had to keep going. I learned to keep a spare filter in the truck after that. The fuel was from flying J and when I removed the filter it was full of larger size rust and crap. I would quess that by shutting the truck of the dirt would "fall away" for awhile.
I know this isnt the "real , default to 3rd gear limp mode" but not sure if this is simular to what you are seeing. My filter was about 3 weeks old at the time.


This scenario can be instantly confirmed with this tool:


http://www.kennedydiesel.com/images/Dmax-fuel-filter-rest1.gif

[mark45678]

I had my 2001 go into limp mode due to air getting past the primer on the filter head. I vaccuum tested it my self , the problem was self caused.... I got a bad tank of fuel that had high water content and cloged the filter up on a very cold AM . I desided a quick fix was to limp home (2 miles) and put a 150 watt drop light on the filter housing and warm up the fuel (not a good ideal) . this over heated some of the plastic parts in the primer section causing them to change shape some. Well it seams it would go down the road fine for 40~60 mile as long as you didnt pull anything or as for full power for more then 2~3 seconds. It would go in to limp mode where it would only rev to about 1800 rpm and had maybe 75 hp . you could pull over and turn the truck off and restart it and 70% of the time it was fine some times you had to hit the primer bulb 5~6 times and it was fine after that. Dealer told me at the time a new housing was 500.00 getting a break on parts (20 mins to install) , best part was it was on national back order and I had to wait 35 days to get one..... WRONG , traded in that truck that week , and forgot about the problem! I would guess that JK filter / pump set up would have fixed that issue and made the rest of the fuel system last longer.

[KompressorMan]

It was the code 0093 in the computer. After I got the truck back to our facility, I had one of our guys take the entire filter assembly off and completely disassemble it checking for worn or torn seals. He couldn't find a single thing wrong with it so he put it back together and reinstalled it. Also, this has been a pretty persistent problem everytime I tow I can pretty well expect it. I did replace the fuel filter no more than a week before it did it the last time.
John, you are probably right about the filter and lift pump. I should have a credit with you on some mirrors I returned a while back. I'll try to fax an order to you tomorrow. I don't know what your talking about on the 02 reprogram though, please explain
Thanks for the help
Herb

[DickWells]

My son had his 03 LB7 recalled this winter to have his fuel filter replaced. Have these 01's in the previous notes been replaced, already? If not, then GM owes you a new complete filter assembly. He didn't know what the difference was between the old and the new.
Interestingly, I had my 04 LB7 go limp the other day, on a hill down in northern Ar. Wouldn't shift out of 4th gear, no lock-up. I was towing in tow-haul mode. Forced a down shift from 5th lock-up and pulled the hill OK, then wouldn't up shift after we topped out. The down shift was abrupt and I felt a skip.
I pulled over at the first opportunity, and set up my Hypertech programmer and pulled the codes, then cleared them and drove on. Codes were PO341 - PO700 - PO735. Don't have access to my son's manuals. Can someone tell me what they are?
Truck's running fine, still, but regardless, I think John's lift pump and pre-filter is a good idea. Ashamed to say, I don't even have a spare filter with me! Can't wait to get to my in-laws in Or. and do some maintenace.
Dick Wells:)

[Kennedy]

P0735 is 5th gear slip from memory. Incorrect ratio by definition.

How long since the Allison spin on was replaced?