Got a start problem thats really got me banging my head against the wall. 03 Dodge 3500 5.9 cummings bone stock 303000 miles. Started out as the motor would have to turn and turn to finally crank. When i turned the key motor would turn very slow and slowly speed up until it started. Problem got progressively worse (took more turns and time to speed up enough) until one day went out and it turned up to a certain point and never cranked, just spun. Seemed electrical to me so had both batteries checked. One was bad replaced it with new 1000 ca battery. Just to be sure put all new cables on the truck 2/0 welding wire for both negatives crossover and started wire with well crimped on lugs and new terminals. still spun slow and would not crank, actually seemed like it had gotten worse just turned slow. Went and got a new starter but that on and still no luck tries and quits like it has a dead battery spins a couple times and quits. Any ideas or future test I can do to try and narrow this down would be greatly appreciated.

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update: after a full charge on both batteries the motor spins good now, but still no start just spins. From my research on this forum im thinking fuel issue. Any other ideas? Anybody how to test for fuel pressure?

 

Likely an injector or injectors. If even one returns too much fuel, it causes a hard start or no start issue. With that many miles, I wouldn't be surprised that the injectors are indeed at fault.

Really no point in finding out which ones are at issue because you'll be constantly replacing them.

 

Isnt there a way to check for returned fuel. Im on a pretty tight budget (who's not) and id like to test a little more before it goes to the diesel shop or i start putting parts on.