Full Floater Posted January 29, 2016 Share Posted January 29, 2016 In my 78 RS600L, I have an EM6-300. Not the original engine and im not sure what the original engine was. I have an electric fuel lift pump mounted behind the fuel filters that is energized by the ignition ON. Is this a factory lift pump? Its working just fine and makes priming the system and fresh filters a breeze. Just curiousDon't mind the red wire...that's just a mickey mouse and temporary ground for a marker light I had to jimmy rig recently. Quote Link to comment Share on other sites More sharing options...
Timmyb Posted January 29, 2016 Share Posted January 29, 2016 Do you still have the priming pump on the side of the fuel pump? I've not seen any on any diesels we have except the Cummins isx. Do they use them in place of a hand priming pump? Quote Link to comment Share on other sites More sharing options...
Full Floater Posted January 29, 2016 Author Share Posted January 29, 2016 I don't see a hand priming pump on the injection pump or anything that might resemble a lift pump Quote Link to comment Share on other sites More sharing options...
Freightrain Posted January 29, 2016 Share Posted January 29, 2016 Looks like a regular Carter style electric pump. I'm guessing it is someones handywork to fix some kind of issue.Can you take a picture of the side of the injection pump? If there is no hand pump or lift pump then I guess that is why they put an electric one on it? 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Full Floater Posted January 30, 2016 Author Share Posted January 30, 2016 Here you are, pics of the pump. Yeah, that looks just like the electric pump that's on mine. What did these use as a lift pump from the factory? Did the IP pull fuel from the tank on its own? Im having what seems to be a common Mack issue, with it having an irregular idle from what I thought was worn governor springs; but im wondering if the electric pump is pushing fuel at a different psi then what the injection pump requires?? Just a thought that crossed my mind..... Quote Link to comment Share on other sites More sharing options...
Mack Doctor Jr. Posted January 31, 2016 Share Posted January 31, 2016 Def no hand primer on there. Sometimes what I find is if air is getting in the system the truck will smoke a little white since it's not burning fuel properly. If the gov is hunting at an idle you do have a gov issue. Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted January 31, 2016 Share Posted January 31, 2016 Air in the fuel creates a slow timing effect.Airated fuel starts injection slower. Quote glenn akers Link to comment Share on other sites More sharing options...
terry Posted January 31, 2016 Share Posted January 31, 2016 First pic. in post #5 clearly shows the original lift or supply pump. terry Quote Link to comment Share on other sites More sharing options...
Full Floater Posted January 31, 2016 Author Share Posted January 31, 2016 Is that in fact a lift pump, or where the pump used to be? I don't see any lines going to or from it. Is it safe to run an electric in conjunction with the factory pump? Im assuming there was an air intrusion issue or drain back problem at one point and someone put and electric on there as a band aid solution. Im happy with how its been working however. I will be buying another electric lift pump to keep in the tool box in case it fails somewhere out in them bushes... Quote Link to comment Share on other sites More sharing options...
terry Posted January 31, 2016 Share Posted January 31, 2016 That is a original lift pump, no primer on it, the fuel originally came from tank to primary filter, than to suction side of pump then pushed it through secondary filter then to injection pump. And they didn't alway have the primer pump on the lift pump. I would guess the original pump failed, they only have a couple of plastic check valves in them. terry 1 Quote Link to comment Share on other sites More sharing options...
Full Floater Posted January 31, 2016 Author Share Posted January 31, 2016 Good solid info, thanks Terry.Kevin Quote Link to comment Share on other sites More sharing options...
blackdog2 Posted January 31, 2016 Share Posted January 31, 2016 Ive seen so many people over the years that didn't no about check valves a case of either and still wouldn't start!!! change valves start right up ,10.00$ Quote Ed Link to comment Share on other sites More sharing options...
Mack Doctor Jr. Posted January 31, 2016 Share Posted January 31, 2016 Ya there is 2 plastic plungers in the lift pump if you take the to plugs out on the top. Quote Link to comment Share on other sites More sharing options...
Full Floater Posted February 1, 2016 Author Share Posted February 1, 2016 So you're saying that's most likely whats wrong with the factory pump? Would you recommend that I dig into it and revert back to using it? I will if that's a better way. Quote Link to comment Share on other sites More sharing options...
Freightrain Posted February 1, 2016 Share Posted February 1, 2016 Those two hexes on the top of the pump are the valves. My 237 had issues when I first tried to start it. Would not prime(Mine has hand primer mounted where the front hex is at).The fuel line should come from the tank to the FRONT fitting on the bottom, then out the rear to the filter(if I recall correctly). Doesn't look like there are any lines hanging on the bottom, so I'm guessing they are using the electric pump.Remove those caps on top, I think there are small springs in there too? Been a month so I don't recall all the details of mine. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Quickfarms Posted November 18, 2022 Share Posted November 18, 2022 I am resurrecting this thread because I have a similar problem on a E6 350. it became hard starting and would lose prime ant the filters were partially empty. I replaced all suction and return lines from the injection pump to the tank and had the lift pump rebuilt. The problem persists and now the shutdown rack sticks and will not go back in without cranking the engine and it still loses prime. Could the rebuilt lift pump be pushing too much side pressure on the cam causing the rack to jamb? So this thread has me thinking about adding an electric pump to prime the truck and or replace the lift pump. Can I remove the lift pump and block off the hole and replace it with an electric pump or should I put the electric pump before the lift pump. next what electric pump to use? Quote Link to comment Share on other sites More sharing options...
fjh Posted November 18, 2022 Share Posted November 18, 2022 9 hours ago, Quickfarms said: I am resurrecting this thread because I have a similar problem on a E6 350. it became hard starting and would lose prime ant the filters were partially empty. I replaced all suction and return lines from the injection pump to the tank and had the lift pump rebuilt. The problem persists and now the shutdown rack sticks and will not go back in without cranking the engine and it still loses prime. Could the rebuilt lift pump be pushing too much side pressure on the cam causing the rack to jamb? So this thread has me thinking about adding an electric pump to prime the truck and or replace the lift pump. Can I remove the lift pump and block off the hole and replace it with an electric pump or should I put the electric pump before the lift pump. next what electric pump to use? I don't think the lift pump is you issue ! A sticking rack is more due to scored plungers etc. Is your fuel pump AMBAC or Bosch ! Quote Link to comment Share on other sites More sharing options...
Quickfarms Posted November 18, 2022 Share Posted November 18, 2022 50 minutes ago, fjh said: I don't think the lift pump is you issue ! A sticking rack is more due to scored plungers etc. Is your fuel pump AMBAC or Bosch ! The sticking rack only started after the rebuilt lift pump was installed Quote Link to comment Share on other sites More sharing options...
fjh Posted November 18, 2022 Share Posted November 18, 2022 1 hour ago, Quickfarms said: The sticking rack only started after the rebuilt lift pump was installed Try running some Standyne or reputable substitute thru if you can make it run again! check the filters for water etc! Quote Link to comment Share on other sites More sharing options...
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