diggin dirt Posted June 27, 2021 Share Posted June 27, 2021 i dont know how to search the archives i guess, but my old 77 2 valve loses prime over night, a little ether helps but dont sound to good on motor. i cant find any leaks and have changed both filters. i would consider a electric pump tp prime with but dont see a good way to tie it in. stumped? Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/ Share on other sites More sharing options...
Joey Mack Posted June 27, 2021 Share Posted June 27, 2021 NO ETHER!!!! There may be an issue with the lift pump on the side of the injection pump... The electric pump is something I would do on my stuff just to see if it helps, etc... hell try it, but there should be a functioning check valve in the lift pump... Post a pic of the pump, I'm curios. I assume an Ambach, Jojo 2 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-475947 Share on other sites More sharing options...
Gravelguy413 Posted June 28, 2021 Share Posted June 28, 2021 I just went through this on a 96 em7-300 fully mechanical. Threw a bunch of parts at it including new lift pump and fuel lines etc. It ended up being the little jumper between the heads for the return fuel. One of the fittings was a little loose. Problem solved Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-475955 Share on other sites More sharing options...
h67st Posted June 28, 2021 Share Posted June 28, 2021 Agree with Joey...look at those check valves. My hand primer was sucking air, caused mine to lose prime overnight. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-475956 Share on other sites More sharing options...
h67st Posted June 28, 2021 Share Posted June 28, 2021 Agree with Joey...look at those check valves. My hand primer was sucking air, caused mine to lose prime overnight. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-475957 Share on other sites More sharing options...
MACKS Posted June 28, 2021 Share Posted June 28, 2021 My fix was the plastic return line to the front of the head.. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-475965 Share on other sites More sharing options...
mrsmackpaul Posted June 28, 2021 Share Posted June 28, 2021 As I have mentioned many times before, if your loosing prime when the motor isnt running its the return to the tank side of things Pressurise the fuel system to maybe 10 - 15 psi at the fuel cap on the tank and look for leaks Do this before you start blowing a whole of money buying parts hoping to fix it All these check valves and things always leak back with a little bit of age, the return fuel line siphons fuel back up from the tank to keep it primed when it isnt running, old mechanical injector pump motors are desgined this way Need to remember millions upon millions of diesel motors have been built with the same basic injection system and dont need a electric fuel pump Good luck Paul Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-475967 Share on other sites More sharing options...
diggin dirt Posted June 28, 2021 Author Share Posted June 28, 2021 thank you guys for info on stuff to look at, im old and old school and cant put picture on cause i still have a flip fone. my brain refuses to update and thats part of the reason i still drive a 77 r model, i guess me and the old dump truck understand each other, at least we did before this latest curveball. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476002 Share on other sites More sharing options...
MACKS Posted June 30, 2021 Share Posted June 30, 2021 Get a piece of bicycle tube with the valve in it,clamp one end tight clamp the other end around the fuel tank fill,air it up and leave it for a while,if there’s a leak you’ll find it.. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476128 Share on other sites More sharing options...
MACKS Posted June 30, 2021 Share Posted June 30, 2021 Shut the the valve at the bottom of the tank if u have one.. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476129 Share on other sites More sharing options...
Joey Mack Posted June 30, 2021 Share Posted June 30, 2021 The inner tube tool is an awesome idea, mind if I use it to fix my own junk?? 😉 Jojo Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476136 Share on other sites More sharing options...
mrsmackpaul Posted June 30, 2021 Share Posted June 30, 2021 Thats pretty much what I do, one thing to remember is the tank will most likely be vented so I just wind the regulator right back and leave it on Apart from the obvious problem of over pressuring the tank which wont happen as the tube will pop off, the regulator allows you to leave the air connected and walk away and look and study etc Paul 2 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476137 Share on other sites More sharing options...
MACKS Posted June 30, 2021 Share Posted June 30, 2021 1 hour ago, Joey Mack said: The inner tube tool is an awesome idea, mind if I use it to fix my own junk?? 😉 Jojo Don’t mind at all,even trade for all the help I’ve gotten from you.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476143 Share on other sites More sharing options...
diggin dirt Posted July 10, 2021 Author Share Posted July 10, 2021 On 6/28/2021 at 4:17 AM, MACKS said: My fix was the plastic return line to the front of the head.. i put 12 lbs in tanks and found leak behind fan thank you 1 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476642 Share on other sites More sharing options...
diggin dirt Posted July 10, 2021 Author Share Posted July 10, 2021 On 6/28/2021 at 5:55 AM, mrsmackpaul said: As I have mentioned many times before, if your loosing prime when the motor isnt running its the return to the tank side of things Pressurise the fuel system to maybe 10 - 15 psi at the fuel cap on the tank and look for leaks Do this before you start blowing a whole of money buying parts hoping to fix it All these check valves and things always leak back with a little bit of age, the return fuel line siphons fuel back up from the tank to keep it primed when it isnt running, old mechanical injector pump motors are desgined this way Need to remember millions upon millions of diesel motors have been built with the same basic injection system and dont need a electric fuel pump Good luck Paul found leak behind fan on return using 12 lbs in tanks thank you 1 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476643 Share on other sites More sharing options...
Joey Mack Posted July 10, 2021 Share Posted July 10, 2021 Great!!! I tuned a skipping, E-6, 2 valve today, my customer was very happy... we need to keep these great machines running.... jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476645 Share on other sites More sharing options...
Licensed to kill Posted July 10, 2021 Share Posted July 10, 2021 What was causing the "skipping"?. Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476646 Share on other sites More sharing options...
Joey Mack Posted July 11, 2021 Share Posted July 11, 2021 It was easy, popping through the exhaust, and poor revving, and a lot of smoke. I cooled it off and ran the valves, #6 was wicked tight... cranked it and it Purred like a Dog.... I did raise the idle speed to about 600... .. Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-476649 Share on other sites More sharing options...
Steve Hill Posted July 18, 2021 Share Posted July 18, 2021 How much is the pressure typically on the lift pump on a cs-200/250 milliner? Mines been hard to start I guess it’s been bleeding down too ! also,ran out of fuel sitting at shop,now won’t restart, not pulling any fuel over , it’s not been run in a good while i opened a couple injector lines to bleed it, not helping help ! Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-477008 Share on other sites More sharing options...
Steve Hill Posted July 18, 2021 Share Posted July 18, 2021 I meant midliner Quote Link to comment https://www.bigmacktrucks.com/topic/67159-engine-loses-prime-over-night/#findComment-477009 Share on other sites More sharing options...
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