Will Posted August 30, 2022 Share Posted August 30, 2022 Have a Mack vision with a v-Mac 3 in it. It’s very sluggish starting, engine turns over very slow then will eventually start. any idea why it would be doing this? Any help would be great. Thanks. Quote Link to comment Share on other sites More sharing options...
Adkat Posted August 30, 2022 Share Posted August 30, 2022 Most likely bad earth, check/ clean/ tighten connections from block, starter, chassis and isolator if you have one. Make sure you don't have a dud battery in the mix, charge and test them individually. Check armature housing on starter for loose bolts, the 2 long ones that run from back to front of housing, seen lots of these come loose and cause hard starting. See how you get on. 1 1 Quote Link to comment Share on other sites More sharing options...
Popular Post Dirtymilkman Posted August 30, 2022 Popular Post Share Posted August 30, 2022 Just so he knows...."earth" means ground up here in the states. 3 Quote Link to comment Share on other sites More sharing options...
Popular Post Mackpro Posted August 31, 2022 Popular Post Share Posted August 31, 2022 (edited) A bad starter drawing to many amps could the the cause . Of course start by charging each individual battery separately and load testing . Them move on to the battery cables and grounds . Engine to frame ground on driver side frame rail. The ground breaker and auxiliary starter solenoid by the wiper motor on the firewall under hood . All need to be checked thoroughly. We were lucky and the shop had a large battery and starter tester and could measure starter draw when starting. It measured up to 1400 amps. We had a few bad starters they maxed that reading out . The draw was so high that it took so much voltage away from the engine ECM that it would not fire the EUPs and the engine would not start. The owner was convinced it was a fuel issue because you could use starting fluid to get the engine spinning fast enough that it took the load off the batteries and the engine ECM had enough voltage to then start running. Acted just like a fuel issue. One way to check with out a starter amp flow tester is to use a volt meter and check voltage at the fuse of the engine Ecm on the fire wall while cranking . If below 9 volts then you got voltage issue. You can also check the same way on the VECU fuse in the fuse box inside the cab . Edited August 31, 2022 by Mackpro 2 1 Quote Link to comment Share on other sites More sharing options...
Adkat Posted August 31, 2022 Share Posted August 31, 2022 Thanks DMM, easy to get confused with different terminology. Mackpro, over 1400amps, those starters must've been glowing red hot. Engine to frame earth/ ground on the ones down here in Aus will be on the passenger side👍 1 1 Quote Link to comment Share on other sites More sharing options...
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