Ok so about 2 months ago my fuel pump on my 6.0 went out causing damage to all 8 injectors which in turn had to be replaced as well. My gas mileage got alot better and my truck had a lot of power except for the fact my transmission would have rough shifting/hesitations, i would have violent vibrations ans shuddering sounds at idle, and in the cold I would have thick white smoke out my exhaust. I went out and purchased a Scangauge II to monitor my FICM voltage and it was 48v (normal) so I wasn't really too concerned on my FICM. Well last week a day before I went on vacation I filled my tank and as soon as I did my gas mileage got alot worse, I didn't have as much power, and my engine would miss really bad at times. At first we thought the fuel was bad but as I looked into my symptoms I saw it was possibly my torque converter going out! That all makes since but does a bad torque converter make your engine miss and your gas mileage decrease?

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Also I have a white chalky residue around my degas cap. For that I suspect EGR issues over head issues. My heads were checked 2000 miles ago when my truck was in the shop for injectors and they appeared to be replaced and the bolts looked brand new plus my exhaust has no coolant scent in it. I do plan on doing my EGR delete here really soon so hopefully that issue will be fixed.

 

You may want to check your high end fuel pump, I was having the same problem with mine, got it replaced and runs fine now, thet will delete your egr info as well. hope this helps. cost is about $1000.00

 

I'm reading my bill and that was the fuel pump replaced. Sorry should have been more specific on that one.

 

You might want to call and check, my truck has two, suprised, yes.. It has a lower and upper pick up fuel pump. sorry maybe I should have been more clear.

 

I should do that. The bill just said high end fuel pump it never classified which one was replaced though. I should call and ask. I just don't understand why my gas mileage could be so good until I fill it up and it decreases, the engine is running at higher RPMs, and I misfire occasionally.

 

These trucks only have ONE fuel pump, the fuel pump is on the oposite side of the housing where your frame mounted fuel filter is. you do have 2 fuel filters though. You also have 2 oil pumps, the engine oil pump/low pressure/ and a high pressure oil pump to pressurise the topside of the injectors.

 

Could it be my HPOP?

 

It could be just a dirty or sticking EGR valve, it will run like crap and mileage will be cut in half if the valve is stuck or the orinings onit are faulty.

 

Well there is traces of coolant outside my degas bottle. I bet that's what it is. I better do my EGR delete ASAP!

 

you can pull the egr valve and see if there is any coolant puddled up there or if it is wet with coolant, easiest way to tell