Truckie Harbison Posted June 29, 2022 Share Posted June 29, 2022 I’m working on my son’s Superliner and need some help. The truck had sat for quite a while and my brother gave it to my son to restore just before he passed away. The truck ran fine until a few days ago. It started to act up and wouldn’t idle. As long as the rpm’s stayed above 800, it was fine. I went out to start it the other day and it would only run on ether. Determined the plastic check valve on the left side of the pump had broke. Replaced both check valves and now it will run, but won’t start without ether. I let it idle for over an hour, shut it off and tried to start it again right away and it wouldn’t start. The only way it will start is with ether. Any advice would be greatly appreciated Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/ Share on other sites More sharing options...
Popular Post Joey Mack Posted June 30, 2022 Popular Post Share Posted June 30, 2022 NO ETHER!!!!!!! they run right if compression is right and fuel is delivered right... If you keep putting ether to it, it will be one of 3 things,,, addicted to drugs,, or bent rods.... and lets not make #3 happen... jojo 1 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501635 Share on other sites More sharing options...
mechohaulic Posted June 30, 2022 Share Posted June 30, 2022 assuming the new plastic check valves and springs were installed correctly. and brass washers under plugs ( or possible hand pump) were new or in good shape had been installed;; i go with bleeding fuel back due to air leak in fuel system. can't be after hand pump; that's pressure. before pump is suction. did you road test after it's running ? idle over an hr might not be enough on system check for rough running? all broken plastic parts of check valve accounted for ? possible pieces in pump?? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501644 Share on other sites More sharing options...
Truckie Harbison Posted June 30, 2022 Author Share Posted June 30, 2022 I took it for a short drive and it acted fine, although I had the idle set too high. I’ve had it running 3 different times for an hour each time idling around 1200 rpms. Each time I shut it off and immediately try to restart it and it won’t fire. Short spray of ether and it fires right off and runs fine. the check valve broke into 2 pieces so pretty confident I got it all. Didn’t have new brass washers so I reused the old ones. They appeared to be ok. I just don’t see how it can lose prime in a matter of 2 seconds. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501646 Share on other sites More sharing options...
mrsmackpaul Posted June 30, 2022 Share Posted June 30, 2022 First things first, when your trying to start it does it have smoke coming out the exhaust ? If it has smoke and wont start you have fuel and prime isnt your problem If you dont have smoke you have a leak Cant give anymore help until we get the basics sorted first Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501664 Share on other sites More sharing options...
fjh Posted June 30, 2022 Share Posted June 30, 2022 Agree with this you need to start at the front and work back on this! Drain back valve First / check valves in the transfer pump ? Have you looked at the lines and filters yet? Judging by how quick the start issue happens it may be the fuel pump rack sticking at low RPM! Try some fuel conditioner Standyne or howes fuel condtioner See if it smartens up! Just something to try! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501678 Share on other sites More sharing options...
Truckie Harbison Posted June 30, 2022 Author Share Posted June 30, 2022 Went out this morning and it started right up. Shut it off and tried again and it started. Reset the idle and took it for a short drive. It died pulling in to my driveway and wouldnt restart. No smoke when it won’t start. when I set the idle, it wont idle below 700-750, and it surges up to 800 or 900. Once it falls to 600 rpm’s it’s gonna die. what is the rack? I’m very mechanical, but not a big diesel person. Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501680 Share on other sites More sharing options...
Popular Post fjh Posted June 30, 2022 Popular Post Share Posted June 30, 2022 (edited) 10 minutes ago, Truckie Harbison said: Went out this morning and it started right up. Shut it off and tried again and it started. Reset the idle and took it for a short drive. It died pulling in to my driveway and wouldnt restart. No smoke when it won’t start. when I set the idle, it wont idle below 700-750, and it surges up to 800 or 900. Once it falls to 600 rpm’s it’s gonna die. what is the rack? I’m very mechanical, but not a big diesel person. Bud if it will start again make sure the tank is venting crack the fuel cap loose and go for a drive ! if the tank breather is plugged it will create a vacum and suck the fuel back to the tank! Edited June 30, 2022 by fjh 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501682 Share on other sites More sharing options...
doubleclutchinweasel Posted June 30, 2022 Share Posted June 30, 2022 2 hours ago, fjh said: Bud if it will start again make sure the tank is venting crack the fuel cap loose and go for a drive ! if the tank breather is plugged it will create a vacum and suck the fuel back to the tank! Been there. Done that. It can happen. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501685 Share on other sites More sharing options...
Truckie Harbison Posted June 30, 2022 Author Share Posted June 30, 2022 Ruled out a tank venting issue. Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501698 Share on other sites More sharing options...
mechohaulic Posted July 1, 2022 Share Posted July 1, 2022 '79 =electrical shut off ?not cable if i remember ;;; weak switch ? ether start enough to pressure switch to open , clean gallon jug with diesel fuel and short hose to suction side if transfer pump. run unit for a minute or two . runs /idles shut it down and try restart. if it starts i'd be looking at the lines and hoses to tank. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501727 Share on other sites More sharing options...
Truckie Harbison Posted July 1, 2022 Author Share Posted July 1, 2022 I plan on trying that tomorrow. This truck has the mechanical fuel shut off. Hoping it’s something simple. Gotta have it ready so my son can take it to Walcott in a couple weeks for the Jamboree. Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501733 Share on other sites More sharing options...
mechohaulic Posted July 1, 2022 Share Posted July 1, 2022 mechanical cable shut off- with cable all the way in for run mode, is there still at least 1/4 in to spare by handle. meaning cable has "slack" enough for fuel to obtain full open? or at pump end ;; where cable goes through lever fitting . outer cable housing broke any where . did you try when it won't start to physically move pump lever by hand to confirm full travel 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501736 Share on other sites More sharing options...
mechohaulic Posted July 1, 2022 Share Posted July 1, 2022 i would still go with the bleed back theory . when were the fuel filters changed ? even if the primary filter was screwed up ( gasket/ hair crack etc ) there would be some dampness . anything after the transfer pump would show fuel leak from pressure. another situation which could be a simple fix by so many on this site if we/ they were there to see it. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501737 Share on other sites More sharing options...
mrsmackpaul Posted July 1, 2022 Share Posted July 1, 2022 Time to skip all the guess work, you have a fuel leak, nothing more complex than that So as I have said many times, get some old inner tube, a couple of big flat washers, a air fitting to match the compressor in your shop, a fitting to screw onto the air line fitting, and a hose clamp big enough to fit over the filler cap Cut the inner tube big enough to cover the filler and go down the sides a bit Put a hole in the middle of the inner tube, air-washer-inner tube-washer and another fitting to clamp all of these together Then pop the inner tube over the filler neck, and some air pressure, not a lot, wind the regulator down as low as it goes on the shop compressor Then search for the wet spot, by the sounds of it, it's gunna be easy to find Hope thisis of some help This isnt a lift pump or filter or anything else, this is a bad fuel leak Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501787 Share on other sites More sharing options...
MACKS Posted July 1, 2022 Share Posted July 1, 2022 49 minutes ago, mrsmackpaul said: Time to skip all the guess work, you have a fuel leak, nothing more complex than that So as I have said many times, get some old inner tube, a couple of big flat washers, a air fitting to match the compressor in your shop, a fitting to screw onto the air line fitting, and a hose clamp big enough to fit over the filler cap Cut the inner tube big enough to cover the filler and go down the sides a bit Put a hole in the middle of the inner tube, air-washer-inner tube-washer and another fitting to clamp all of these together Then pop the inner tube over the filler neck, and some air pressure, not a lot, wind the regulator down as low as it goes on the shop compressor Then search for the wet spot, by the sounds of it, it's gunna be easy to find Hope thisis of some help This isnt a lift pump or filter or anything else, this is a bad fuel leak Paul The way I’ve done this with a fat bicycle tube is just cut a two foot length of tube with the valve in,clamp one end tight and clamp the other end over the tank fill,air it up.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501789 Share on other sites More sharing options...
Truckie Harbison Posted July 1, 2022 Author Share Posted July 1, 2022 I appreciate the advice. I’ll get the stuff rounded up and give that a shot. I’m hoping the issue is that simple. It just seems odd that it won’t start 2 seconds after it was running, and that it will start in the morning after sitting all night and not starting the night before (it started this morning no problem) Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501803 Share on other sites More sharing options...
MACKS Posted July 1, 2022 Share Posted July 1, 2022 3 hours ago, Truckie Harbison said: I appreciate the advice. I’ll get the stuff rounded up and give that a shot. I’m hoping the issue is that simple. It just seems odd that it won’t start 2 seconds after it was running, and that it will start in the morning after sitting all night and not starting the night before (it started this morning no problem) Yup usually when hard starting after they sit overnight = a fuel line leak or return line leak.. Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501818 Share on other sites More sharing options...
Truckie Harbison Posted July 1, 2022 Author Share Posted July 1, 2022 Ok, but I’m having the exact opposite problem that you described. It’s starts easily in the morning after sitting all night. To me, if there is a leak, sitting all night would cause it to lose prime and not start in the morning. Instead, once I have it running, shut it off, and immediately try to restart it, it won’t start. I hope it’s a line leak, but it seems weird that a leak would cause it to lose prime in a matter of 2 seconds, but sitting overnight helps it start easy. Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501819 Share on other sites More sharing options...
Onyx610 Posted July 1, 2022 Share Posted July 1, 2022 Sounds like something is expanding due to heat and causing your issue. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501826 Share on other sites More sharing options...
Joey Mack Posted July 1, 2022 Share Posted July 1, 2022 Hmmmm??? have the fuel filters been re-located-or- modified? They are usually mounted below the injection pump... but above the fuel tanks.. with them being above the fuel tank there can be some bleed back, but the lift pump should recover the fuel before it runs dry.. I'm just tossing that out there.. jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501828 Share on other sites More sharing options...
Joey Mack Posted July 1, 2022 Share Posted July 1, 2022 (edited) have you just tried to pull the throttle stop, while it is running, and push it back in before the engine spins down to stop, and see if it picks up fuel and starts back up??? I know i said something about fuel filters, but while i was siting on the toilet,, a minute ago,, I had a thought.... jojo Edited July 1, 2022 by Joey Mack Poor spelling 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501829 Share on other sites More sharing options...
MACKS Posted July 1, 2022 Share Posted July 1, 2022 23 minutes ago, Joey Mack said: have just tried to pull the throttle stop, while it is running, and push it back in before the engine spins down to stop, and see if it picks up fuel and starts back up??? I know i said something about fuel filters, but while i was siting on the toilet,, a minute ago,, I had a thought.... jojo TMI..lol 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501833 Share on other sites More sharing options...
theakerstwo Posted July 1, 2022 Share Posted July 1, 2022 Joey is thinking of a sticking rack and he may be on to the problem. 1 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501837 Share on other sites More sharing options...
mechohaulic Posted July 2, 2022 Share Posted July 2, 2022 check valve on the pump having the return line to tank malfunction. added info of no immediate restart vs proper start after sitting over night changes diagnostic approach, ?? try shut down and put the fuel pedal down right after shut down . not good to raise rpms ON shut down . Quote Link to comment https://www.bigmacktrucks.com/topic/70028-1979-superliner-w-endt676-maxidyne-300-losing-prime/#findComment-501845 Share on other sites More sharing options...
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