Freightrain Posted 3 hours ago Share Posted 3 hours ago Ok, seems my original pump is not keeping up. I can manually pump up 20# but after starting and running it drops to 10# and then barely holds 5# and then it has been just stalling out. I was perplexed with it not wanting to stay running after a few minutes until I put a pressure gauge at the filter and then I can see what is going on. Anyone have the proper part number? Thanks. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/76656-300-lift-pump/ Share on other sites More sharing options...
fjh Posted 3 hours ago Share Posted 3 hours ago 24 minutes ago, Freightrain said: Ok, seems my original pump is not keeping up. I can manually pump up 20# but after starting and running it drops to 10# and then barely holds 5# and then it has been just stalling out. I was perplexed with it not wanting to stay running after a few minutes until I put a pressure gauge at the filter and then I can see what is going on. Anyone have the proper part number? Thanks. Bro before you go condemning the pump ! Have you checked the tank vent! Is the lines to and out of the filters clear! I have been burned by other people’s diagnostic conclusions before ! Check before you canon! just sayin! Quote Link to comment https://www.bigmacktrucks.com/topic/76656-300-lift-pump/#findComment-595751 Share on other sites More sharing options...
Freightrain Posted 3 hours ago Author Share Posted 3 hours ago Fuel system was no issue last fall. Now it suddenly won't run with new motor. I had lots of issues with getting this primed up when I first started it and it only had 2ft of hose to can of diesel. Then it really had problems drawing from tank. I replaced the new primer pump I bought with old bailing ring version from the 237 and it works much better. I can hear it returning fuel to the tank after pumping up 20# of pressure. After starting the pressure drops and won't recover. I know it should be 15# idling as that was what the 237 had. Too bad it is different pump or I would try it. New lines from lift to filter and back to injection pump. Remaining lines are good from before. New filter also. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/76656-300-lift-pump/#findComment-595752 Share on other sites More sharing options...
fjh Posted 2 hours ago Share Posted 2 hours ago Ok just checking! You blew thru the lines new or not good to check! Trying to avoid any parts canyoning for no reason! Quote Link to comment https://www.bigmacktrucks.com/topic/76656-300-lift-pump/#findComment-595753 Share on other sites More sharing options...
terry Posted 10 minutes ago Share Posted 10 minutes ago Did you check the check valves and springs in the lift pump? terry Quote Link to comment https://www.bigmacktrucks.com/topic/76656-300-lift-pump/#findComment-595769 Share on other sites More sharing options...
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