sprtkr1

Thanx for the input. I had them done last fall for the third time. Starts and idles fine. Some times feels like a governor kicking in at about 1600 rpms. The bad thing is it doesn't always do it but getting more frequent. Do you think I got some bad fuel? No water in the separator and the fuel in tanks looks good. Thanx again.

Well, I replaced the power steering pump as well and my fuel leak disappeared. but I am still having the same problem. Every now and then it feels like I'm running over a washboard in the road. only lasts for a second or two and when I let off the throttle it quits. The only other time this happened was I almost ran it out of fuel. Found out how inaccurate my fuel gauge was then. It also seems to have a slight miss and is bogging down when I get to higher rpms. 1600 to 1800. Checked for blockage in fuel tanks but they are clean as a whistle. Not throwing any codes. Seems to be getting worse. I can even feel it when bobtailing. Could the dealer pull codes even though they aren't showing up my dash? It's a 2008 CXU613 with 485HP MP8. Thanks for any thoughts.

I replaced the fuel pump on my CXU613 MP8. Now it has fuel leakage from the weep hole between fuel pump and power steering pump. I took them back off and separated them again. Then I removed the cover plate from the power steering pump where the fuel pump mounts. I found the shaft that drives both pumps to be grooved in 3 places where the seals and small bearing ride. I had no problems with leakage before. My question is do you think extra pressure from the new fuel pump was enough to cause a leak where none existed before?

Thanks for the reply fjh. Good to know that. After cleaning off all of the grease, I found that it was impossible for the bearing to have moved in the forks, which is what I originally thought. For some reason I thought the zerk hung down straight. But it is at the 4 oclock position like you said. Just found out I need a new clutch so will just have everything replaced while it's torn down. Thanks again.

No I didn't have the gun hooked up at the time. I don't see how it could've moved either. My only experience with transmissions is my 4 wheelers. Didn't know if big trucks had the same set up. I may have broken something. This truck has the clutch cable. Didn't know if that made a difference. Thanks for the info.

Was greasing throw out bearing on my 2008 cxu613. I had the clutch depressed with a tool specifically for that job to gain access to the throw out bearing grease fitting. I must not have set right this time because the tool slipped and allowed the clutch to release suddenly. When I reset the tool and looked at the bearing, the fitting had moved about 1 inch to the right. Have I broken something? Clutch seems to work as far as moving the release bearing back and forth on the shaft. Still seems to me like it shouldn't have rotated the housing with the fitting. Thanks for any ideas or info y'all may have on this numb skull move by me!

Well finally got the problem fixed. Congratulations to fjh and steeler. You were right. Even though I didn't want to believe it, it turned out that the number 4 injector was galled and cracked. Also had damaged the injector cup, so had all 6 cups replaced again even though they were replaced about a year ago. This thing has been nothing but a money pit literally since the day I drove it home. But for now it is starting real good. Thanx for everyone's input.

Sorry, for got to say this does not have the air purge system.

Thanx for the ideas and thoughts on this. Sorry I didn't reply earlier but was on the road all week. Thinking about trying the fuel pump but leaning toward an injector problem. Becomes hard to start in under 5 mins after shutdown. Seems like losing prime that fast has to be one heck of a drain back. Truck runs good. No coolant in the fuel and no fuel in the oil. When I get this solved I'll sure let you know. Thanx again.

Found dampness around what looks like a weep hole on bottom of fuel transfer pump. Could this have anything to do with it?

Thanks for the info. I'll have them checked again, by someone else this time.

I know this issue has been discussed many times on here before. I've read many threads on it. But few if any tell us how or if they ever got it fixed. My 08 cxu613 mp8 485hp loses prime in as little as 20 minutes. Used to hold it longer, but gettin worse with time. I've changed 2 check valves, fuel filter stand, seals on banjo bolts and checked fuel lines. The mack dealer checked injector cups in January and said they're ok. They've been changed twice. The only clue I have is I get air bubbles when the truck is running and after I shut it down in the driver's side fuel tank only. Maybe a cracked pickup tube? I promise to let y'all know if I ever get this problem solved. Is there a check valve on the back of the motor? Thanks for any thoughts.

Thanks for all of the ideas. I've always said I know just enough to be dangerous. That's why I only work on my own trucks. These are great ideas and I appreciate all the help !

Thanks for the info. I do appreciate it. Didn't know they were just slotted. Every bolt on this repair has been a battle, but I'm winning.

I've got a 2008 Pinnacle with the MP8 485HP motor. I'm removing the EGR cooler to have it cleaned. I know I'll have to remove the turbo to get it out. One of the bolts on the back side where the turbo mounts seems almost impossible to get at . I want to separate the turbo without disturbing the VGT box to get at this bolt. I noticed there is a tamper proof seal on the band clamp where the intake of the turbo attaches to the exhaust side of the turbo. Easy to remove this seal, BUT if I do take the clamp off and remove the intake side first to get at that bolt will I be hurting anything? Thanks for any insight on this matter. Mike.