Chase1210 Posted November 4 Share Posted November 4 Hi all, I have a 2010 CXU with an MP7. I replaced the fuel filter housing and now I can not get the truck to fire. I've tried all the things you would normally do. Now I'm convinced I may have a line messed up or a banjo bolt. I noticed as I was putting in back together that 1 of the bigger sized banjo bolts is bigger than the others. It has same threads but is a bit longer than the others. Does anyone know which line the bigger bolt goes go? I've attached a diagram of where each line goes and this is not how my lines are routed. Does anyone know if there is a different diagram with the routing different than this? Everything was original when I took it apart. When I pump the hand pump, it will get hard after 15-20 pumps but then after trying to start the prime seems to go away, that is why I feel like a line may be wrong. Maybe someone could post some pictures of there housing and lines so I can compare to how I have them? Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/ Share on other sites More sharing options...
The Heinz Posted November 4 Share Posted November 4 I didn't have a VIN for a 2010 CXU with an MP7, but this is from a Granite of the same year with an MP7. Number 10 down there is an overflow valve on the return side, I don't remember if that can cause your issue or not. We never reuse these seals, but we are a dealership, so take that as you will. Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561307 Share on other sites More sharing options...
Chase1210 Posted November 4 Author Share Posted November 4 25 minutes ago, The Heinz said: I didn't have a VIN for a 2010 CXU with an MP7, but this is from a Granite of the same year with an MP7. Number 10 down there is an overflow valve on the return side, I don't remember if that can cause your issue or not. We never reuse these seals, but we are a dealership, so take that as you will. Thank you! That looks more like what I've got. Now... (3) Tank to ECU. (17) ECU to filter housing (12) Return from head to filter housing (4) and (8) to and from filter housing to pump, but which is which? My vin # is 1M1AW02Y1AM011833 if that helps? Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561311 Share on other sites More sharing options...
The Heinz Posted November 4 Share Posted November 4 (edited) It certainly helps! #4 should be the return to the pump, Impact describes it as "FUEL FILTER BRKT-FUEL PUMP," while #8 should be the feed line from pump to filter, described as "FUEL PUMP-MAIN FILTER." Both of those banjo bolts use the same washer, Mack #20852765. The overflow valve according to your VIN is #21458307 should you need it. Sorry for the late reply, I'm now a Front Counter Salesman, so I am much, much busier than before. I've already had the privilege to order and quote parts for several older Macks, including an 80's DM. Edited November 4 by The Heinz Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561336 Share on other sites More sharing options...
Joey Mack Posted November 4 Share Posted November 4 Heinz... you are doing a great job here.. What an asset you are.. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561338 Share on other sites More sharing options...
Chase1210 Posted November 4 Author Share Posted November 4 1 hour ago, The Heinz said: It certainly helps! #4 should be the return to the pump, Impact describes it as "FUEL FILTER BRKT-FUEL PUMP," while #8 should be the feed line from pump to filter, described as "FUEL PUMP-MAIN FILTER." Both of those banjo bolts use the same washer, Mack #20852765. The overflow valve according to your VIN is #21458307 should you need it. Sorry for the late reply, I'm now a Front Counter Salesman, so I am much, much busier than before. I've already had the privilege to order and quote parts for several older Macks, including an 80's DM. I really appreciate it. Hopefully I can get it sorted out in the morning. I may have some more questions for you! Thank you!! Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561347 Share on other sites More sharing options...
fjh Posted November 5 Share Posted November 5 13 hours ago, Chase1210 said: I really appreciate it. Hopefully I can get it sorted out in the morning. I may have some more questions for you! Thank you!! Heinz you the man! Your definitely out pace us on that newer stuff! just keep your ears open and listen to the guys who are having the miss fortune of working on the stuff You'll learn lots! The fuel system on these is a bit of a dogs breakfast! the hokey little hand primer and all the check balls are a pain! These turds needed to have put an electric primer pump on these would have elevated a few problems ! I Could go on and on but I won't ! I've said it before ! These engines have a good foundation However some of the dumbass addons are frustrating! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561393 Share on other sites More sharing options...
Chase1210 Posted November 5 Author Share Posted November 5 15 hours ago, The Heinz said: It certainly helps! #4 should be the return to the pump, Impact describes it as "FUEL FILTER BRKT-FUEL PUMP," while #8 should be the feed line from pump to filter, described as "FUEL PUMP-MAIN FILTER." Both of those banjo bolts use the same washer, Mack #20852765. The overflow valve according to your VIN is #21458307 should you need it. Sorry for the late reply, I'm now a Front Counter Salesman, so I am much, much busier than before. I've already had the privilege to order and quote parts for several older Macks, including an 80's DM. what position on the housing should the overflow valve be in? i can not get this thing to run. i have good fuel flow from the tank when i pressurize it , but truck will not stay running and hand primer loses its pressure after every attempt to start Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561396 Share on other sites More sharing options...
The Heinz Posted November 5 Share Posted November 5 If I'm not mistaken, the overflow valve screws into the head as the return-to-FF Housing side. This is me guessing as I haven't worked much on this particular setup, but could the overflow valve stick open and allow the fuel to drain back earlier than needed (Someone smart please help me out!) Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561398 Share on other sites More sharing options...
fjh Posted November 5 Share Posted November 5 Are you sure you got the lines in the right spot on the transfer pump! ??? I'm not a guru either on this ! that said its got to be something simple ! Is the fuel pump putting out ??? What was your original issue before you changed the housing?? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561400 Share on other sites More sharing options...
Joey Mack Posted November 5 Share Posted November 5 Not sure if im helping, but the fuel enters the rear port on the side of the head, and comes out through the port on the front of the head.. Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561401 Share on other sites More sharing options...
Chase1210 Posted November 6 Author Share Posted November 6 this was my problem. that check valve goes on the front side of the housing. trucks running! still doesn’t have sh** for boost tho. max 25 psi. wtf!! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561440 Share on other sites More sharing options...
The Heinz Posted November 6 Share Posted November 6 Noted! I guess that valve does make a difference. Joey, fjh, and the others will have better answers for the lack of boost, but I know the CAC hot pipe (passenger's side) has a bad tendency to leak there, requires replacing the two blue boots and all four clamps. Could also be something in the EGR system causing a boost leak too, Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561453 Share on other sites More sharing options...
fjh Posted November 6 Share Posted November 6 So you think its a fuel pressure problem but it could be something else!!? Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561463 Share on other sites More sharing options...
Chase1210 Posted November 7 Author Share Posted November 7 On 11/6/2024 at 9:07 AM, fjh said: So you think its a fuel pressure problem but it could be something else!!? I have already checked all the potential boost leak spots pretty extensively. I suppose the CAC could have a leak somewhere that I'm missing down low where I can't really see. After I was unable to find a boost leak I kind of switched gears to thinking it was a fuel problem, but I did not find any fuel blockages anywhere when I swapped the filter housing. How can I check fuel pressure without a computer? Where would I tie a mechanical gauge into the sytstem? Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561552 Share on other sites More sharing options...
fjh Posted November 7 Share Posted November 7 Hate to say it but you’re chasing your tail without a computer! You need to know what that fuel pressure is and if the egr valve is closing as it should! Also if the mass flow is working correctly! Do you have codes engine light on ? Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561554 Share on other sites More sharing options...
Chase1210 Posted November 7 Author Share Posted November 7 38 minutes ago, fjh said: Hate to say it but you’re chasing your tail without a computer! You need to know what that fuel pressure is and if the egr valve is closing as it should! Also if the mass flow is working correctly! Do you have codes engine light on ? The EGR isn't the problem 😉... No codes, no lights. What is a good computer or scanner I can buy that will work with this truck that doesn't cost $1000? Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561557 Share on other sites More sharing options...
fjh Posted November 7 Share Posted November 7 34 minutes ago, Chase1210 said: The EGR isn't the problem 😉... No codes, no lights. What is a good computer or scanner I can buy that will work with this truck that doesn't cost $1000? If your truck is deleted it makes it harder to diagnose! It can be the turbo causing this! The vgt may be stuck! if the egr is corked then possibly the vgt is stuck but not knowing the fuel pressure leavse you grasping at straws J pro is one I haven't worked with it Macpro may chime in and lead you to a better option I am not a guru on these so your talking with the wrong guy! If the turbo is stuck it will not throw a code period its one of those gut feeling things! Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561559 Share on other sites More sharing options...
Chase1210 Posted November 7 Author Share Posted November 7 6 minutes ago, fjh said: If your truck is deleted it makes it harder to diagnose! It can be the turbo causing this! The vgt may be stuck! if the egr is corked then possibly the vgt is stuck but not knowing the fuel pressure leavse you grasping at straws J pro is one I haven't worked with it Macpro may chime in and lead you to a better option I am not a guru on these so your talking with the wrong guy! If the turbo is stuck it will not throw a code period its one of those gut feeling things! At one point in this trucks life it had a brand new turbo/vgt, still had no boost. Then it was discovered that the egr was stuck open. Hence the egr not being the problem anymore. ...very frustrating Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561560 Share on other sites More sharing options...
Joey Mack Posted November 7 Share Posted November 7 you may be able to make up a fitting to attach to the banjo fitting port on the rear side of the head. I dont remember if there are any plugged ports in the heads fuel gallery.. Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561565 Share on other sites More sharing options...
fjh Posted November 7 Share Posted November 7 I took an old sensor and hollowed it out and made my own real gauge adapter! 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74712-2010-mack-cxu-with-mp7-fuel-issue-after-replacing-housing/#findComment-561566 Share on other sites More sharing options...
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