danovak Posted January 15, 2009 Share Posted January 15, 2009 I work for a shop and we have various model Macks the one that we are having problems wiyh is a RB690S. Every once in awhile it will not start, it cranks fine but will not fire up and then if you leave the truck sit for a couple of hours it will start right up. Has been to Mack dealer for this problem but they could not find anything wrong. Was wondering were i could find any information on the shutdown system on this truck. It is an electrical system not a cable shutoff. Where is the solenoid or sender actually located on the pump and is it difficult to change ? We have none of the current model engine ,vmac instructional booklets and do you know anyplace to get these booklets without spending an arm and leg ? Or is there a website that has all the information like a motor manual ? Thanks for any information provided. Quote Link to comment https://www.bigmacktrucks.com/topic/7981-em7-300-wont-start-at-times/ Share on other sites More sharing options...
rt76jim Posted January 15, 2009 Share Posted January 15, 2009 I work for a shop and we have various model Macks the one that we are having problems wiyh is a RB690S. Every once in awhile it will not start, it cranks fine but will not fire up and then if you leave the truck sit for a couple of hours it will start right up. Has been to Mack dealer for this problem but they could not find anything wrong. Was wondering were i could find any information on the shutdown system on this truck. It is an electrical system not a cable shutoff. Where is the solenoid or sender actually located on the pump and is it difficult to change ? We have none of the current model engine ,vmac instructional booklets and do you know anyplace to get these booklets without spending an arm and leg ? Or is there a website that has all the information like a motor manual ? Thanks for any information provided.check the tach sensor on the left side of the bellhousing,I have had the plug spread on some rd690s,rd690p 2001 and found that to fix it. Quote Link to comment https://www.bigmacktrucks.com/topic/7981-em7-300-wont-start-at-times/#findComment-29219 Share on other sites More sharing options...
fjh Posted January 16, 2009 Share Posted January 16, 2009 check the tach sensor on the left side of the bellhousing,I have had the plug spread on some rd690s,rd690p 2001 and found that to fix it.More stuff to try!asuming it is vmac 1 or 2 Not eteck and IF it happens any old time ,also asuming you have no fault light on ,In my opinion you need to have the fuel pump plug repined take it to a dealer and have them put new pins on the fuel pump conector.this very often will cure the problem.next (IF) the problem happens when the engine gets warm Get a bucket of water and pour it over the back part of the fuel pump then try start the the unit if it starts the fuel pump needs to come off and needs internal repairs try these two things first the water trick is the odvious cheaper of the two (IF) your symtom is as discribed.Note This info is provided from the Mack book of hard knocks and is not writen in any manual on the face of the planet to the best of my knoledge.. Quote Link to comment https://www.bigmacktrucks.com/topic/7981-em7-300-wont-start-at-times/#findComment-29227 Share on other sites More sharing options...
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