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Cummins 3.9 pump timing

atvfan2000 ยท 2017-04-02 23:05

I have a 2001 Case 75Xt with the Cummins 3.9 and a Bosch VE injection pump. It is slow to start. It puffs dark smoke while cranking and a dark cloud when it fires. When the engine is warm it starts right up. While running it makes very little smoke. It seems to crank really slow before it starts. I currently have 2 (tested and confirmed good) 900 CCA batteries connected for testing. One is in the stock location using stock cables the other is connected directly to the starter. It still turns over slow. I have cleaned and tested the cables. One battery or 2 does not seem to change how fast it turns over. The starter seems good but I have not had it tested. My question is if the injection timing is too far advanced will it cause it to turn over slow? I am considering delaying it to see what happens but thought I would ask first. The engine has less than 100 hours on the rebuild (I was told) and seems to run great once its running. Thanks

Replies5
  1. #1jacobd2017-04-03 00:15

    Injection timing has no effect on how fast the motor turns over while starting. That's up to your starter motor (and cables, batteries ect) Advanced timing can make it take a longer period of cranking to "fire off" however. If you set it at half or full throttle does it start quicker? Try unbolting the starter and running it with no load. Does it try to jump out of your hand or is it kind of sluggish?

  2. #2Birken Vogt2017-04-03 00:29

    One of the ways starter motors can die is to slowly get weaker and weaker and it sounds like that is what you have got here although I am not going to go tell you to buy a new one just to try, it sounds like that might be one way to do it.

  3. #3thepumpguysc2017-04-03 04:29

    Jacobd is correct.. the inj. pump timing has no effect on cranking SPEED of the engine.. Starter condition & type of engine oil.. I think would be the main contributors.. IF it was a fresh engine I'd say, bearing tightness too..

  4. #4atvfan20002017-04-03 06:49

    Throttle position does not seem to effect the starting. I will pull the starter and take it to a local starter rebuilder and have it tested. Thanks

  5. #5atvfan20002017-04-08 22:45

    I replaced the starter with a $100 Chinese special from EBay. It now starts like a new one. Thanks for the help.