Bj Hinson Posted January 16, 2014 Share Posted January 16, 2014 I have 2 identical ch 600 Mack trucks. Unit 110 is a 1994 and unit 111 is a 1995. Both have 400 Mack engines. They will both crank over until the batteries are almost dead before they start. I added check valves behind the fuel filter housing,replacing the main fuel line from the tank to the filter housing and also the three lines from the filter housing to the fuel pump. There isn't any fuel leaking around the transfer pump or dust accumulation to indicate a fuel leak. I think it could be the selenoid on the fuel pump as I have already replaced the selenoid in the dash by the fuse box. Any help would be appreciated as I have had these units out to the mechanics shop numberous times and am getting tired of paying time and time again for zero results. Quote Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/ Share on other sites More sharing options...
hatcity Posted January 16, 2014 Share Posted January 16, 2014 Being that you are in Canada, how cold is it?Have you been plugging the trucks in at nite?How many miles/kilos are on the motors?Rings may be losing it so it takes more to build up temp for combustion Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/#findComment-226968 Share on other sites More sharing options...
Bj Hinson Posted January 17, 2014 Author Share Posted January 17, 2014 It does it even when they are in the shop with heat on Quote Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/#findComment-227170 Share on other sites More sharing options...
Glensts Posted January 18, 2014 Share Posted January 18, 2014 If you use the hand pump before you start it is there fuel there? Or does it take quite a few pumps before you actually get fuel at the hand pump? Occasionally mine won't start right away and I have to pump the primer pump at least 50 times before I get fuel and then it'll start fairly quick. It happens to me a couple times a year if it sits for extended amount of time. Quote Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/#findComment-227259 Share on other sites More sharing options...
Macktech689 Posted January 19, 2014 Share Posted January 19, 2014 Check all the return fuel lines from the heads to the injection pump, they look like small plastic air lines. any leaks cause loss of prime. Also check the jumper between the heads by the valve covers Quote Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/#findComment-227628 Share on other sites More sharing options...
FayettesFinest Posted January 20, 2014 Share Posted January 20, 2014 I'm not sure if these have mechanical fuel pumps or not, if they do, this theory will make a little more sense, lol. Even though this is severly frowned upon, have you tried starting them with ether? Maybe your fuel pumps are getting weak, and it's taking longer for them to push fuel to the engine. If it starts off ether, the pump may suck better turning at a high RPM? I'm not much of a mechanic, more of a parts changer. Just spitballing with my idea. Good luck. Quote Being in the process of getting your CDL's is like sitting on death row... Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/#findComment-227707 Share on other sites More sharing options...
Bj Hinson Posted January 20, 2014 Author Share Posted January 20, 2014 On the 94 it is the primer pump. I pumped the shit out off it and it started better. I haven't tried it on the 95 yet but both had new primer pumps last year. Seems weird that it would break that fast Quote Link to comment https://www.bigmacktrucks.com/topic/34255-1994-1995-ch-600s-hard-starting/#findComment-227721 Share on other sites More sharing options...
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