LB7 power loss

[Mark Rinker]

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.

[rapidoxidationman]

I'm curious as to exactly HOW the stealership "cleaned the injectors" on that LB7 for anything less than the labor involved in removing the valve covers... and if the fuel was suspect, why didn't they drain the fuel tank?

[markelectric]

I have had a similar problem with my 01. Mine seems to be heat related in the fact that it only did it when the outside temp was over 90 deg. I got a bad load of fuel in the Jan 2010 and froze the truck. EVERY fuel line that we could see was sucked flat at that time. Summer of 2010 the low power started. At the time in the summer I too thought I had a bad load of fuel. I could change the filter and get a bit over a hundred good miles of towing out of it when the power faded away. By the third filter (each one being dumped and nothing but clean fuel being seen),I realized something else was causing the problem. I can only assume that I have a bad line somewhere that gets soft with the heat and will go flat when a bit more suction is applied. I bought one of Kennedys fuel lift pumps last fall right after my busy season was over and because of the "dreading to lower the tank" I did not install it untill last month. I have towed many trailers thruout the fall, winter and spring but with the cooler temps, I have noticed no problem. My busy season is on now and because of the need for some wider goosenecks hauled first the Chevy shortbed has not been a part of the mix yet. With the heat now it would be a good test. By end of next week it will have to be on the road with a load.

Was that a definitive answer to your problem?......No But with what I felt last summer and the research I did I think I am ready to try to tow again.

Good Luck

[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.