rspatola88 Posted February 17, 2021 Share Posted February 17, 2021 (edited) Hi, new to Mack and need help I have a E7 400 Mack with a jaccob Brake set up, here's the story the truck had a head gasket problem that was building coolant pressure that we were adding coolant hopping to get a few more weeks out if it till we had time to get the truck in the shop, then we noticed a lack of power and noticed a misfire it seemed to be cylinder 2 and 3 we checked this by cracking the fuel lines loose one at a time, when removing the valve cover we found cylinder 3 exhaust yoke broken, from there we, Replaced both heads, gaskets , all 6 injectors , and injector lines , and the one broken yoke, piston's and cylinders seemed fine on visual inspection, adjusted valve timing according to the book and have rechecked since 16 on intake and 24 on exhaust, put all back together there is no more coolant pressure problem to still has a misfire , we checked compression and leak down all seem ok, we tried checking witch cylinder the misfire is from by disconnecting each individual fuel pump wire one at a time and it seems that the misfire jumps around, OHM checked all fuel pump wires seems to be ok , swapped the computer with another truck and other truck ran fine with computer not sure where to go next Edited February 17, 2021 by rspatola88 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/ Share on other sites More sharing options...
OldRedMack Posted February 17, 2021 Share Posted February 17, 2021 Leave the unit pump wires hooked up and try cracking the injector lines 1 at a time to try and locate. My guess is you have a bad eup and it's not supplying enough fuel for the new injectors. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-469162 Share on other sites More sharing options...
MACKX Posted February 18, 2021 Share Posted February 18, 2021 How many miles are on this engine? Are all the valves adjusted about the same.... as in you didn’t have to crank one to the end of threads to get adjustment correct? Were the lifters or the EUP lifters checked? The ceramic rollers break or the metal rollers score up and cause a miss that way, especially if you had broken valve train components 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-469196 Share on other sites More sharing options...
fjh Posted February 18, 2021 Share Posted February 18, 2021 (edited) So this comment holds some weight being as you had a yoke failure to begin with you should check the lifters !on the failed yoke cyl! That being said the fact that the miss seems to jump around sort of indicates the computer is possibly trying to compensate for irregularity in engine rpm smoothness not sure on this! But I have been personally involved in chasing this issue several times wasting time To no avail ! My advice is After you check the lifter! if the engine is only doing this at Idle and is not effecting performance, Leave the dam thing alone and drive it! Its an annoyance thing only! Not an indication of a failure of any sort! Just an opinion Edited February 18, 2021 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-469211 Share on other sites More sharing options...
Popular Post Joey Mack Posted February 18, 2021 Popular Post Share Posted February 18, 2021 have you installed a pressure gauge on the fuel inlet hose to the engine, or "T" into the output line before the regulator and run the truck with a load and read the pressure? I have one made up with 20' of hose so it can ride with me in the cab.. 80-100 PSI is good. if the pressure bounces a lot, may even get down to 50 or less theres a good chance the pump is slipping or failing.. If you have the fuel sensor located at the regulator, you ca take it out, install a "T" then put the sensor back in and put the gauge on too, and test it... if it's good, Then refer to "F's" post. Jojo 3 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-469253 Share on other sites More sharing options...
fjh Posted February 19, 2021 Share Posted February 19, 2021 (edited) 😇GOOD Advice Joe! Edited February 19, 2021 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-469299 Share on other sites More sharing options...
Sflora Posted March 13, 2021 Share Posted March 13, 2021 We have an 2001 E7 with a miss at idle. Can some one help me with this. Valves are adjusted. Cam next? 502.529.1971 preffered Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470551 Share on other sites More sharing options...
Joey Mack Posted March 15, 2021 Share Posted March 15, 2021 You can use a vise grip and squeeze the fuel hose that is after the regulator. it comes out of the block below #3+4... be careful not to cut the hose.. also if the fuel hose is hard like dry rot, dont do this test... without replacing the line when you are done...... so your truck is probably set to 625 RPM's... it will flucuate about 25 RPM's during the rough idle condition.. if squeezing the line smooths out the idle and you get a firm 625 RPM's, then replace the regulator.... Ok my Canadian friends and Glenn,,, please advise... Jojo ✌️ 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470759 Share on other sites More sharing options...
Joey Mack Posted March 15, 2021 Share Posted March 15, 2021 👍 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470764 Share on other sites More sharing options...
fjh Posted March 16, 2021 Share Posted March 16, 2021 Joe in my opinion You got to be carefull with that test! I have seen more than one pump shaft seal blown out due to over pressuring the system ! had it happen to me more than once! Wern't a happy camper!😡 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470798 Share on other sites More sharing options...
Joey Mack Posted March 16, 2021 Share Posted March 16, 2021 👍yes sir,, it does take some care, and i dont actually close it off completely, but yes it is risky... Thank you for youre opinion..jojo Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470800 Share on other sites More sharing options...
Vmac3 Posted March 16, 2021 Share Posted March 16, 2021 Hey Joey, That test is a good test to see if the regulated pressure is set too low for the fuel system. I would squeeze the return line slowly until the idle stabilizes. Yes F is correct, care has to be taken. If the idle does smooth out then the higher regulated pressure check valve can be installed. But this may lead to other issues such as diesel fuel diluting into the engine oil. I used to recommend installing the updated delta seals on the EUP once the fuel pressure was at 100 psi. Here is the Delta Seal part# 1899-071356. Also there were datafiles that were released by Mack that tried to solve this issue. I say try because it worked sometimes. V 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470808 Share on other sites More sharing options...
Vmac3 Posted March 16, 2021 Share Posted March 16, 2021 I forgot to mention the 100 psi check valve part# is 63AM28. V 2 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470810 Share on other sites More sharing options...
Joey Mack Posted March 16, 2021 Share Posted March 16, 2021 Yes sir... I use a needlenose vise grip, because I can preset the gap in the jaws so that it doesnt completly cut off the return flow. and if its too loose, i turn the knob slowly to set it right... thanks sir.. I like other opinions, I certainly dont want to offer bad advice.. and I also like to learn more, even if it means my way is the wrong way....🤔 Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470828 Share on other sites More sharing options...
Joey Mack Posted March 16, 2021 Share Posted March 16, 2021 (edited) 👍 "V" you always come up with Stats and Mack Info.. and part #'s... I'm quite sure you have helped many here.. jojo Edited March 16, 2021 by Joey Mack More content needed Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470837 Share on other sites More sharing options...
Vmac3 Posted March 17, 2021 Share Posted March 17, 2021 I appreciate the compliments Joey. I always enjoy reading your input as well. If we all can collaborate we can help many. V 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470894 Share on other sites More sharing options...
Joey Mack Posted March 17, 2021 Share Posted March 17, 2021 Actually... there is a new post about an '07 with a rough idle, but goes away when air comp. is pumping.. Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-470896 Share on other sites More sharing options...
Carlaisha83 Posted June 30, 2022 Share Posted June 30, 2022 Hello I’m also having a similar issue. Engine sputters while running. Codes were EUP 2, 3 and 6. Turns out 6 was the bad one. I also switched out all fuel lines. It’s been about 3 weeks and it’s sputtering again. Now saying #2 again. Could it be an injector? Should I just swap out the pump? There’s obviously a price difference….appreciate the help Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-501692 Share on other sites More sharing options...
Joey Mack Posted June 30, 2022 Share Posted June 30, 2022 during the next oil change, drop the pan and check the cam lobes that operate the EUP's.. I have seen this, I am building one right now that had chipped lobes on all six.. Strange to me, but metal doesnt lie... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-501710 Share on other sites More sharing options...
Joey Mack Posted July 1, 2022 Share Posted July 1, 2022 taking a couple hours to check the health of the bottom end, and the cam and lifter's, is not 'work' it's a P.M. The pan gasket and the 30insulators may be re-useable,,,, thats up to you.. If you do not own a 'barring tool' I suggest you get one now.. Monaco tool/ Freedom racing/ Tillman tool's// are where I get my tools.. ..it's under $100.00. ,,, jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/65932-e7-400-mack-misfire-seems-to-move-need-help/#findComment-501719 Share on other sites More sharing options...
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