Severe loss of power - drop in fuel pressure

[deuce]

I just picked up a 2001 3500 with the Duramax a few months ago. We've gone on a few camping trips and the truck is absolutely awesome. This past weekend we were heading to Maine when the truck almost died while cruising down I95. We were running around 75 MPH going up a slight hill when the power plant just about shutdown. We pulled off the road, I tried rev'ing the motor but it wouldn't go above 2 grand. I shut it off, let it sit for a few minutes, fired it back up and it was OK for a few more miles. This happened four more times before getting off the interstate. I stopped at a GMC dealer off of Rte 1, they checked the computer and the code translation was sudden drop in fuel pressure. The tech put in a new fuel filter, no help, the truck died 9 more times on the way home. Here's the interesting part. This only occurs if I'm traveling above 60-65 MPH, regardless of RPM. Any ideas out there? :confused:

[dmaxalliTech]

would like to see data with a tech-2.. likely that speed isnt an issue but rpm is, or fuel pressure is. could be a injector, or issue with fuel pressure not building...you need a trip to MI.

[Black Dog]

Does it have a lopey idle? Has the fuel pump / fuel pressure regulator been replaced? A lot of '01 trucks had a corrosion problem inside the fuel pressure regulator. This would normally cause a lopey idle and no other real issues, but I could imagine that if it got a lot worse it could play havoc with the fuel pressure.

[mackin]

Could be a whole bag of problems,as mentioned above .... Could be a faulty fuel rail pressure sensor,mine took a dumper,but in a different way ... Chances are they would have any of the parts in stock that day nevertheless...Dealer seen a drop in pressure so he changed the fuel filter and sent you on your way,nice try ...Keep us addressed of your resolve ...

How many miles on the 01 ?? Do you know the history on the truck,local trade or auction vehicle ??


Mac

[CntrlCalDmax]

This has happened to me several times, usually while towing and around 70 mph. If I back off the throttle and just try to maintain 60 mph or so, kinda feathering it, power will come back to normal within about 30 seconds. It's so random I haven't tried to find it.

I think hoot has had the same thing happen to him. Check out Continuing power drop off issues (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=004441) for more information.

[hoot]

Yep, mine does it. Not much anymore now cause i don't drive like I used to.

[Maxter]

This happened to me a few times during the winter, totaly unloaded. For some reason there was a restriction in the fuel delivery system between the filter and the thank (man it was hard to prime. Didn't want to rev above 2,000 rpm IF it wasn't stalling all the time. The minute there was even the stightest hill; it would stall. A good night in a warm garage and it was like new again... Go figure... No water in fuel filter either times.

Good luck.

JF.

[deuce]

Thanks to all who have responded. It's nice to know that you're not alone when you start having these problems.

Mackin, you asked some numbers on the truck. The truck is about to clear 60K miles, I bought it from a dealer whom I strongly do not recommend, (General GMC in MA) but the previous owner owns a blasting business and had a gooseneck hitch in the back. So, I'm assuming he hauled his business equip with it. As for stock program, no idea. I'm only getting 18 MPG highway, 10 towing and friends of mine who own the identical truck are getting 20 and 14, and I've heard as high as 22. This may be another clue. I just put a K+N air filter in, and changed the oil to Shell Rotella 5W40 synthetic, and now I also have a new fuel filter.

Anybody else out there getting 20+ MPG?
The truck is scheduled to go into the shop next Tuesday. Hopefully I'll have some answers then.

DmaxalliTech, I'm not sure I understand the data with a Tech-2 question. I'll try to get the exact code before it goes into the shop and forward that on, if that's what you're asking.

CntrlCalDmax, I've messed with the throttle while this is occuring for several minutes. The only way to 'patch' the problem is to pull over, shut it down a wait a few minutes.

Black Dog, the problem is very sudden. All is fine then, no power. A real pain in the ass doing 73 in bumper to bumper traffic on a five lane highway, and yes, I was in the middle lane.

My gut feeling is the ECM is telling the high pressure fuel pump to slack off. The drop in pressure is causing crappy injection and hence, loss of power. Turning off the ignition switch is essentially resetting the ECM and patching the problem. Although I do like the fuel pressure regulator theory. This would be much cheaper.

Thanks again and I'll keep you posted.

[deuce]

dmaxalliTech, I found on my bill of sale from the GMC dealer in ME who replaced the fuel filter the computer code. The line on my bill of sale reads: "Check codes-P0-0093 Check Vac at fuel filter-holds 9-12 in vac, replace fuel filter and road test." I recall looking at the gauge pluged into the fuel rail with him while he was diagnosing the problem. It read about 11 when the motor was turning approx. 2000 RPM. After he replaced the fuel filter, the reading was approx. 3, again at 2000 RPM. He specs said that it should be less then 5 (I don't recall the units). Does this help?

[hoot]

deuce,

I believe if you have to shut the engine down to reset it, your engine has gone into "Limp Home" mode.