losing speed on hills - diesel & fifth wheel

[bginpa]

Sounds like fuel filter problem. That's the 1st thing your should check. Change the fuel fileter. If that doesn't solve your problem then go to some of these other issues. Fuel filter problems will usually show up when you are asking the most from your rig! 2nd note: If you have been using any bio diesel. The Bio diesel is a solvent. It will clean out your system and could have clogged your fuel filter. I stay away from Bio Diesel for that reason. Hope this helps.

Bruce

[Ray,IN]

Originally Posted by bginpa

The Bio diesel is a solvent. It will clean out your system and could have clogged your fuel filter. I stay away from Bio Diesel for that reason. Hope this helps.

Bruce

The other side of the coin. This HFRR test of diesel fuel additives lists biodiesel as it's top rated additive for lubricity. Once your fuel system is clean again clogged filters are not a problem.

[bginpa]

Originally Posted by Ray,IN

The other side of the coin. This HFRR test of diesel fuel additives lists biodiesel as it's top rated additive for lubricity. Once your fuel system is clean again clogged filters are not a problem.

Has not been my experience. We run a fleet of 15 Hwy trucks and tried Biodiesel for about a year. Although Bio might be a lubricant it is also a solvent and we constantly had clogged fuel filters. We were told problem would go away. It never did. Went back to regular diesel. No more fuel filter problems. Extra cost of Bio and all the filter issues not worth it.

[Ray,IN]

Originally Posted by bginpa

Has not been my experience. We run a fleet of 15 Hwy trucks and tried Biodiesel for about a year. Although Bio might be a lubricant it is also a solvent and we constantly had clogged fuel filters. We were told problem would go away. It never did. Went back to regular diesel. No more fuel filter problems. Extra cost of Bio and all the filter issues not worth it.

It depends on the age of the trucks and how much crud is in the fuel tank. IMO very dirty tanks may require a thorough manual cleaning, sure would be cheaper than a case of fuel filters.

[bginpa]

Originally Posted by Ray,IN

It depends on the age of the trucks and how much crud is in the fuel tank. IMO very dirty tanks may require a thorough manual cleaning, sure would be cheaper than a case of fuel filters.

Ya, we were told that too. Only thing is one truck was new and all tanks were sparkling clean. Our conclusion was that the tanks from the fuel company were also contributing to the problem. Bottom line. Bio was too much of a hassle. Not worth it in my opinion.

My question is did they change the fuel filters? Haven't heard the result of that yet.

[wandering1]

Get a Ford.

[elkhornsun]

Originally Posted by wandering1

Get a Ford.

Right because everyone knows how trouble free the Ford PowerStroke engines were in the 2003 timeframe.

The LB7 engine is prone to fuel injection problems with its poor injector design that requires a much higher operating voltage, but the problem is aggravated by fuel starvation. Adding a lift pump would be a good way to insure maximum power from the engine and insure an adequate supply of fuel to the injectors. Fuel is a vital lubricant to the injectors and with inadequate fuel supplied the injectors wear faster.

In addition to regular fuel filter replacement and the lift pump the use of a fuel additive for improved lubricity can help extend injector life.

The Duramax engines produce the most torque in the 1700 RPM area but the most horsepower in the higher 3000-3100 RPM range. You can go into manual mode but in so doing you are likely to experience higher transmission temperatures than when in tow haul mode. The trade-off in part is that in going slower up a long grade there is less air flowing over the cooling fins of the transmission cooler and so temps can increase rather quickly.

At 13,000 lbs. you are operating at the high end of the towing range for any 2003 diesel pickup and performance will not compare well to trucks produced in the last couple years. But going faster rapidly decreases the truck's fuel economy. With my 2011 truck and a heavy load in the mountains an extra 10 MPH translates into a drop in MPG of about 20%. I have to ask myself whether it is worth the extra cost to get somewhere 10 minutes sooner.

[gtmatt]

Replaced the fuel filter and the truck performed better without a load. I had hoped that would translate to towing the fifth wheel, but no luck. Still has the P1093 code. It is looking like a new CP3 pump is in my future, based on what I've read.

Does anyone know of a good diesel repair shop in the Baton Rouge area?

[JohnBoyToo]

Orignally from BR, so I'll check with some folks I rv with down there
(in fact going to meet them in Morgan City for Mardi Gras Rv'ing on Feb 8th !)

Laissez les bons temps rouler

[gtmatt]

Will take suggestions around Slidell as well, as I may end up being closer to there.

[gtmatt]

Dealer could not find anything wrong today, fuel rail pressure was good when they checked it under hard acceleration. I guess maybe the CP3 is just starting to get weak where it only fails to keep up with demand when I'm towing the RV.

Some have said to get a lift pump. The price is a lot nicer than the $1600 for a new CP3 but I'm not certain it's going to fix the problem. And I'd hate to pay for a lift pump and have it not change anything, then have to replace the CP3 as well.

Does anyone run a lift pump on their Chevy/GMC diesel of this age range? I know they could be useful for people added HP tunes, etc. I just wonder if anyone else with a stock truck might have had things work better with a lift pump on.

[fvstringpicker]

GT, what grade are you on when you lose speed and are you blowing a lot of smoke? Also did the dealer check the injector balance?
I had my fuel system lose pressure once at the top on a very long steep grade after I cut the truck off. I had to pump the primer valve at the top of the filter to crank the truck. Folks tell me a lift pump would have prevented the problem. A diesel tech told me to let the truck idle a few minutes to stabilize before cutting it off after a hard pull.
You're pull a heavy load at 12k but I expect with the people, equipment, and accessories, your a couple of thousand over that. You're going to lose speed on grades. I'm more worried about transmission and EGR temps than running.

[gtmatt]

I do not know how to come with a number for the grade, but it doesn't have to be much if the hill lasts a while. I have not been anywhere close to any mountains. I have not noticed any smoke at all.

The RV is 13k, I've weighed it twice. It is the very top end of the rating for the truck, but losing 15-20 MPH off of 65 MPH on the interstate just can't be right. Pretty much any sort of hill, even short ones, I will lose 5 or 10 MPH. Long ones more than that. It is also very slow to accelerate trying to get on the interstate, which is of course dangerous in traffic and when the on ramps are short.

I don't have a pyrometer, but the transmission temperature has been ~175-180 as best I can read the gauge.

[BFlinn181]

I still think you need to add a pyrometer. Also, pay attention to the RPM's, not speed. Keep the engine turning at it's optimum torque by downshifting and monitor EGT to be sure you aren't making the engine work too hard. Dropping that amount of speed on a grade is NOT unusual when pulling the maximum load your truck is designed to haul. I talk from years of experience driving under powered vehicles through mountains. (VW campers) I think if you followed an 18 wheeler through the mountains you would see a similar drop in speed.