martinf Posted April 10, 2017 Share Posted April 10, 2017 (edited) Hey all, ive got a midsixties B75 with a thermodyne engine. I needed to use it but after sitting for half dozen years or so, it quit a minute or two after start up. Turns out the supply pump, APE, wasn't delivering fuel. ..and the hand primer wasn't pulling in fuel either. Turns out the pump cavity was empty and, after filling it with diesel (pulled off the primer body and lifted the check valve) I got the hand primer working and pushed fuel up into the injection pump and all was well. But...now after a couple of days it's doing it again.. Won't run and primer pump won't pull in fuel and push it over to the filter. I probably have hunky old fuel, don't you think? I'll empty the tanks and put in fresh diesel and flush the line up to the pump. Any other ideas? Also, are repair parts available for these little plunger pumps? Or even rebuilt units? thanks for any assistance. martin Edited April 10, 2017 by martinf Quote 1965 Mack B-74, dump1974 Mack R, logging w/Prentice self-loaderwww.somewhereonthemountain.blogspot.com Link to comment Share on other sites More sharing options...
j hancock Posted April 10, 2017 Share Posted April 10, 2017 You also should inspect the fuel lines to see if they wet on the outside, damaged, etc. They may be given you a problem pulling the fuel up from the tank. Old fuel lines can deteriorate inside and cause issues. Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
Mike Posted April 10, 2017 Share Posted April 10, 2017 If no bad fuel lines then try with air compressor, blowing air inside the tank to get fuel up to fuel filter. Quote Link to comment Share on other sites More sharing options...
Freightrain Posted April 10, 2017 Share Posted April 10, 2017 You can get reman lift pump from Mack. I just put one on my 237 last summer. Not cheap, but mine was on the weak side. The primer pump is just plastic buttons(check valves) and sometimes you might just be able to take it apart and clean it and make it work again. I've done that in the past. Just unscrew the plunger part from the lift pump. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
h67st Posted April 10, 2017 Share Posted April 10, 2017 I'm assuming you changed the fuel filter, right? That's a common problem. Quote Link to comment Share on other sites More sharing options...
martinf Posted April 10, 2017 Author Share Posted April 10, 2017 Thanks guys. All good suggestions. Just woke up to find it snowing hard so my Macks gonna have to sit for a while til it melts. Sigh. martin Quote 1965 Mack B-74, dump1974 Mack R, logging w/Prentice self-loaderwww.somewhereonthemountain.blogspot.com Link to comment Share on other sites More sharing options...
martinf Posted April 11, 2017 Author Share Posted April 11, 2017 Well guess what came out of the supply line petcocks on both tanks? Molasses! I've never seen anything this bad before. A gallon of the blackest ooze you could ever imagine. i haven't run this truck in 8 years and it sat lots before that. And when I got her running and parked it at my digging site to load with rock, she sat pointed downhill. And that ooze was filling up other fuel line between the tanks and half way up the supply hose to the pump. Poor pump...no wonder it couldn't pull fuel. makes me want to paint my fuel tanks white so they don't become solar ovens in the summer sun all season year after year! Quote 1965 Mack B-74, dump1974 Mack R, logging w/Prentice self-loaderwww.somewhereonthemountain.blogspot.com Link to comment Share on other sites More sharing options...
41chevy Posted April 11, 2017 Share Posted April 11, 2017 It could be general sludge or Algae,microbe or fungus in the fuel.I run an anti algae / bacterial / fungicide additive in the fuel from Bell Performance in my trucks that lay idle for extended periods. Clean the tanks and lines you should be good to go 1 Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment Share on other sites More sharing options...
martinf Posted April 12, 2017 Author Share Posted April 12, 2017 Cleaning the lines is easy, but how would you go about cleaning the tanks. I've drained them but fresh diesel is not going to dissolve that molasses sludge. I hate take them off and get them steam cleaned and tho gasoline dissolves the sludge, I don't like the idea of any leftover gas being in the tank when I refuel. martin Quote 1965 Mack B-74, dump1974 Mack R, logging w/Prentice self-loaderwww.somewhereonthemountain.blogspot.com Link to comment Share on other sites More sharing options...
Phase 1 Posted April 12, 2017 Share Posted April 12, 2017 A small amount of leftover gas would not hurt anything. Some people add gas to their diesel in the winter to keep it from gelling. 1 Quote Link to comment Share on other sites More sharing options...
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