LB7 power loss

[Oldsalt]

Some questions:

1. How many miles on the truck?
2. Are these the same miles that are on the injectors / injector pump / and fuel pressure regulator?
3. Is the check engine light illuminated? If so, what are the codes retrieved?
4. Any smoke at the exhaust under acceleration?

It sounds like a fuel delivery problem. Since you have effectively eliminated fuel filter restriction as a problem, it points to fuel or fuel delivery componants.

1. Any chance that your last fillup wasn't #2 diesel, but unleaded gasoline? How many gallons of fuel did you add, 100 miles before the problems started? Was it at a BP station, with the dreaded green handles? I have made this mistake once, to the tune of ~24 gallons unleaded fuel on top of the remain ~8 gallons of diesel. I drove the truck for almost 80 miles before first noticing the problem after the first stop. My first thought was a plugged fuel filter, I didn't even notice the gassy smell until I replaced the filter and the truck would not easily restart. Also - the truck had very little power once stopped, but would run fine once up to speed - i.e. under minimal acceleration load. Check your last fill receipt to verify the cost/gallon you were charged, if you still have it. Also you can drain some fuel from the petcock on the bottom of the fuel filter and smell it;

If you are sure that you have good #2 diesel in the tank, AND there is no odd smoke at your tailpipe, you may be experiencing the failure of the high pressure (injector) pump, but that would probably be setting some codes and the Check Engine light.

all components on engine with the exception of water pump are original, truck has 135000 miles. Have used mobil 1 synthetic lubricants in engine and transmission since first oil change.
the check engine light did not come on but tech at dealership said i had a low fuel rail pressure code. the check engine light did come on twice while I was limping home but went out after a few minutes and I haven't checked for any new codes.
No smoke at acceleration and engine runs fine when not pulling a load.
I think the fuel is OK. I have two tanks and was running on the aux tank.
when I stopped for fuel I switched to the main tank. I put two gallons in the main tank and filled the aux tank. Fearing I did have bad fuel I did not use the aux tank returning home. I drained some fuel from the aux tank when I got home and it is fine.
One thing I forgot in my original post, when the tow truck operator was disconnecting my driveshaft he noticed some kind of oil coming from the top
of the transmisson. The chevy tech said I had probably overfilled the engine oil when I changed it and with towing it was coming out the vent.
Also the oil when I returned home is very dirty. I have a 1 micron bypass filter that removes most of the soot normally but this oil is very sooty

[JohnC]

The chevy tech said I had probably overfilled the engine oil when I changed it and with towing it was coming out the vent.
Also the oil when I returned home is very dirty. I have a 1 micron bypass filter that removes most of the soot normally but this oil is very sooty

How much oil is in it? Is it diluted with fuel?

[markelectric]

Ok since I posted earlier I rescheduled a load just to test the pump idea. Same manlift that was on the trailer when the problem occoured almost a year ago. Different trailer, got rid of the 24 ft tag and now using a 28ft goose, both open and low deck style, On similar interstate and hotter temp outside.

Wife was driving (then and now) all went well with the tow. It seems like the lift pump cured the problem.

New problem. Due to the way I need to move trailers, I have been flat towing my 2500 Dodge home behind the 3500 Dodge. Since I used the Chevy, I put it on the trailer for the return trip. When I stopped for fuel, I noticed a fresh oil stain on the trailer deck. It appears that the oil pressure switch that had to be added for the pumps is leaking. I am not sure if it is the switch itself of the fittings leading to it, all I know I had a hell of a time getting that thing in there.

I guess I have another cussing session ahead.....

[Oldsalt]

How much oil is in it? Is it diluted with fuel?

the oil level was slightly above the full mark and very dirty the bypass filter that is installed keeps the oil clean and I had just changed oil and fuel filter'
As for being diluted with diesel I dont know, How do I tell.

[rapidoxidationman]

How does it smell?

How's the viscosity compare with known pure oil?

or the pyro's method:
How quick can you catch it on fire?

[Oldsalt]

How does it smell?

How's the viscosity compare with known pure oil?

or the pyro's method:
How quick can you catch it on fire?

I am away from home at the moment will return at the end of the week.
I will check for new codes and diesel in the oil.
if there is diesel in the oil I am assuming this means I have injectors leaking.
Is that your prognosis?

[rapidoxidationman]

That's sure what it sounds like, given all the factors (LB7, 135K miles, overfull oil) but I'm not an expert. Might be worth the $$ to connect the truck to a techII scanner though.

[DmaxMaverick]

If you have fuel in the oil, a Tech II won't tell you any more about it than what you already know, the PCM is having trouble maintaining rail pressure. This can be caused by several issues including fuel filter plugging, collapsed fuel line, failed fuel filler cap, fuel injector leak, return line leak (internal or external), FRP regulator failure, pump failure, fuel contamination, or a suction-side fuel system leak (not in any specific order). A fuel system return rate test can't be performed "hands off" (with a computer/scanner), and requires a specific procedure to measure the return volume. Not difficult, but in no way "simple".

You can check the oil for fuel contamination easily. Engine at operating temperature, shut down and wait 5-10 minutes. Using a thin, white paper towel or coffee filter, pull the dipstick and allow the oil to puddle on the paper (don't wipe it). If you have fuel in the oil, it will have no problem running off the dipstick and onto the paper. If it's thick and won't "abnormally" drip onto the paper, you probably don't have fuel dilution. After about 5-10 minutes, examine the "ring" of the oil drop on the paper. Oil will create a distinct dark(er), heavy ring. Any fuel in the oil will create an outer ring stain on the paper, much lighter and thinner. Usually, by the time you have enough fuel leaking into the crankcase to cause running and/or fuel system codes, it will be significantly more than a "little overfull", and ultimately, it will dump excess volume out the PCV pipe below the engine, which will make a huge mess under the truck and coat the tailgate and a trailer you may be towing. It's quite obvious at this point.

Heavy, dark, thick engine oil may indicate another problem. If you are within a reasonable service interval, your bypass filtering system has failed, or you have another source of contamination. Excess sooting is usually the cause, and is not uncommon with some heavy power tunes (chip).

Start with the simple or cheap/free things you can check, and eliminate them as you go.

[Oldsalt]

That's sure what it sounds like, given all the factors (LB7, 135K miles, overfull oil) but I'm not an expert. Might be worth the $$ to connect the truck to a techII scanner though.

Arrived home last night and checked trouble codes. Found the following three
P0087
P0234
P1093

The oil level is about 1/2 inch above the full mark, Haven't checked for presence of diesel but suspect that it is, No Smoke when running. I am going to change oil and filters and take to mechanic.
Question, I understand when nozzle starts leaking you will get smoke. But what is leaking when the diesel goes into the oil is it the seal between the injector and cup or what.
Truck runs fine when not pulling the 5th wheel